Filed pursuant to Rule 424(b)(3)
Registration Statement No. 333-204696

LRR Energy, L.P.

MERGER PROPOSAL — YOUR VOTE IS VERY IMPORTANT

Dear Unitholders of LRR Energy, L.P.:

On April 20, 2015, LRR Energy, L.P. (“LRE”) and Vanguard Natural Resources, LLC (“Vanguard”) entered into a merger agreement (the “merger agreement”), pursuant to which a subsidiary of Vanguard will merge with and into LRE, with LRE continuing as the surviving entity (the “merger”), and, at the same time, Vanguard will purchase all of the limited liability company interests in LRE GP, LLC, the general partner of LRE (“LRE GP”), resulting in both LRE and LRE GP becoming wholly owned subsidiaries of Vanguard. The LRE GP conflicts committee has determined that the merger agreement is advisable to and in the best interests of LRE and its unitholders who are not affiliates of LRE GP and has approved the merger agreement and recommended that the board of directors of LRE GP approve the merger agreement. Based upon, among other things, the recommendation of the LRE GP conflicts committee, the board of directors of LRE GP has determined that the merger agreement and the transactions contemplated by the merger agreement, including the merger, are in the best interests of LRE and its unitholders, and has unanimously approved the merger agreement, the merger and the other transactions contemplated by the merger agreement and the board of directors of LRE GP has recommended that unitholders vote to approve the merger agreement.

Under the terms of the merger agreement, holders of LRE common units will receive 0.550 common units of Vanguard for each LRE common unit held (the “merger consideration”). The exchange ratio for the merger consideration is fixed and will not be adjusted to reflect changes in the price of LRE common units or Vanguard common units prior to the closing of the transactions contemplated by the merger agreement. The merger consideration is valued at $8.93 per LRE common unit eligible to receive the merger consideration based on the closing price of Vanguard’s common units as of April 20, 2015, representing a 12.6% premium to the closing price of LRE’s common units of $7.93 on April 20, 2015. In addition, under the terms of the merger agreement, Vanguard will issue and deliver 12,320 Vanguard common units to the members of LRE GP in exchange for all of the limited liability company interests in LRE GP. The number of Vanguard common units to be issued to the members of LRE GP was determined based upon the 0.550 exchange ratio for the merger consideration.

Vanguard has also entered into an Agreement and Plan of Merger (as it may be amended from time to time, the “Eagle Rock merger agreement”) with Eagle Rock Energy Partners, L.P. (“Eagle Rock”) and Eagle Rock Energy GP, L.P., the general partner of Eagle Rock (“Eagle Rock GP”), pursuant to which, subject to the terms and conditions thereof, an indirect subsidiary of Vanguard will merge with and into Eagle Rock, with Eagle Rock continuing as the surviving entity and a wholly owned indirect subsidiary of Vanguard (the “Eagle Rock merger”). Prior to entering into the Eagle Rock merger agreement, Vanguard obtained the consent of the board of directors of LRE GP, as required by Section 4.2 of the merger agreement, pursuant to a letter agreement by and among Vanguard, LRE GP and LRE. Neither the Vanguard unitholders nor the LRE unitholders are entitled to vote with respect to the approval of the Eagle Rock merger agreement or the Eagle Rock merger, although Vanguard unitholders are entitled to vote with respect to the issuance of Vanguard common units to Eagle Rock’s unitholders pursuant to the Eagle Rock merger agreement.

If the transactions contemplated by the Eagle Rock merger agreement are consummated, immediately following the later to occur of the transactions contemplated by the merger agreement and the transactions contemplated by the Eagle Rock merger agreement, it is expected that LRE unitholders will own approximately 11.8% of the outstanding common units of Vanguard. If, however, the transactions contemplated by the Eagle Rock merger agreement are not consummated, immediately following the completion of the transactions contemplated by the merger agreement, it is

TABLE OF CONTENTS

expected that LRE unitholders will own approximately 15.1% of the outstanding common units of Vanguard. The common units of LRE are traded on the New York Stock Exchange under the symbol “LRE,” and the common units of Vanguard are traded on the NASDAQ Global Select Market under the symbol “VNR.”

LRE is holding a special meeting of its unitholders at Two Allen Center, 1200 Smith Street, the Forum Assembly Room on the 12th Floor, Houston, TX 77002 on October 5, 2015 at 10:00 a.m., local time, to obtain the vote of its unitholders to approve the merger agreement and the transactions contemplated thereby. Your vote is very important, regardless of the number of units you own. The merger cannot be completed unless the holders, as of the record date of the special meeting, of a majority of the outstanding LRE common units vote to approve the merger agreement and the transactions contemplated thereby at the LRE special meeting. Certain affiliates of LRE, as holders of certain of the issued and outstanding LRE common units, have entered into an amended and restated voting and support agreement with Vanguard, pursuant to which they have agreed to vote all of their LRE common units in favor of the approval of the merger agreement and to take other actions in furtherance of the merger. Collectively, these LRE unitholders hold LRE common units representing approximately 30.5% of the votes of LRE’s outstanding common units as of August 27, 2015.

Based upon, among other things, the recommendation of the LRE GP conflicts committee, the board of directors of LRE GP recommends that LRE unitholders vote “FOR” the approval of the merger agreement and the transactions contemplated thereby, “FOR” the merger-related compensation proposal and “FOR” the adjournment of the LRE special meeting if necessary to solicit additional proxies if there are not sufficient votes to approve the merger agreement at the time of the LRE special meeting.

On behalf of the board of directors of LRE GP, I invite you to attend the LRE special meeting. Regardless of whether you expect to attend the LRE special meeting in person, we urge you to submit your proxy as promptly as possible through one of the delivery methods described in the accompanying proxy statement/prospectus.

In addition, we urge you to read carefully the accompanying proxy statement/prospectus (and the documents contained in or incorporated by reference into the accompanying proxy statement/prospectus), which includes important information about the merger agreement, the proposed merger, LRE, Vanguard and the LRE special meeting. Please pay particular attention to the section titled “Risk Factors” beginning on page 44 of the accompanying proxy statement/prospectus.

On behalf of the board of directors of LRE GP, we thank you for your continued support.

Sincerely,

 
Eric D. Mullins
Co-Chief Executive Officer of LRE GP, LLC,
the general partner of LRR Energy, L.P.

Neither the Securities and Exchange Commission nor any state securities commission has approved or disapproved of the securities to be issued under the accompanying proxy statement/prospectus or determined that the accompanying proxy statement/prospectus is accurate or complete. Any representation to the contrary is a criminal offense.

The accompanying proxy statement/prospectus is dated September 3, 2015 and is first being mailed to the unitholders of LRE on or about September 4, 2015.

TABLE OF CONTENTS

LRR Energy, L.P.
 
Heritage Plaza
 
1111 Bagby Street, Suite 4600
 
Houston, Texas 77002

NOTICE OF SPECIAL MEETING OF UNITHOLDERS
TO BE HELD ON OCTOBER 5, 2015

To the Unitholders of LRR Energy, L.P.:

Notice is hereby given that a special meeting of unitholders of LRR Energy, L.P., a Delaware limited partnership (“LRE”), will be held at Two Allen Center, 1200 Smith Street, the Forum Assembly Room on the 12th Floor, Houston, TX, 77002 on October 5, 2015 at 10:00 a.m., local time, solely for the following purposes:

These items of business, including the approval of the merger agreement and the proposed merger, are described in detail in the accompanying proxy statement/prospectus. Among other things, the LRE GP conflicts committee has determined that the merger agreement is advisable to and in the best interests of LRE and its unitholders who are not affiliates of LRE GP and has approved the merger agreement and recommended that the board of directors of LRE GP approve the merger agreement. Based upon, among other things, such recommendation of the LRE GP conflicts committee, the board of directors of LRE GP has determined that the merger agreement and the transactions contemplated by the merger agreement, including the merger, are in the best interests of LRE and its unitholders and recommends that LRE unitholders vote “FOR” the proposal to approve the merger agreement and the transactions contemplated thereby, “FOR”

TABLE OF CONTENTS

the advisory merger-related compensation proposal and “FOR” the adjournment of the LRE special meeting if necessary to solicit additional proxies in favor of such approval.

Only unitholders of record as of the close of business on August 28, 2015 are entitled to notice of the LRE special meeting and to vote at the LRE special meeting or at any adjournment or postponement thereof. A list of unitholders entitled to vote at the LRE special meeting will be available in LRE’s offices located at Heritage Plaza, 1111 Bagby Street, Suite 4600, Houston, Texas 77002, during regular business hours for a period of ten days before the LRE special meeting, and at the place of the LRE special meeting during the meeting.

Approval of the merger agreement and the transactions contemplated thereby by the LRE unitholders is a condition to the consummation of the merger and requires the affirmative vote of the holders, as of the record date of the special meeting, of a majority of the outstanding LRE common units. Therefore, your vote is very important. Certain affiliates of LRE, as holders of certain of the issued and outstanding LRE common units, have entered into an amended and restated voting and support agreement with Vanguard, pursuant to which they have agreed to vote all of their LRE common units in favor of the approval of the merger agreement and to take other actions in furtherance of the merger. Collectively, these LRE unitholders hold common units representing approximately 30.5% of the votes of LRE’s outstanding common units as of August 27, 2015.

Your failure to vote your LRE common units will have the same effect as a vote cast “AGAINST” approval of the merger agreement and the transactions contemplated thereby.

By order of the board of directors,

  
Eric D. Mullins
Co-Chief Executive Officer of LRE GP, LLC,
the general partner of LRR Energy, L.P.

Houston, Texas
 
September 3, 2015

YOUR VOTE IS IMPORTANT!

REGARDLESS OF WHETHER YOU EXPECT TO ATTEND THE LRE SPECIAL MEETING IN PERSON, IT IS IMPORTANT THAT YOUR COMMON UNITS BE REPRESENTED. WE URGE YOU TO SUBMIT YOUR PROXY AS PROMPTLY AS POSSIBLE (1) BY TELEPHONE, (2) VIA THE INTERNET OR (3) BY MARKING, SIGNING AND DATING THE ENCLOSED PROXY CARD AND RETURNING IT IN THE PREPAID ENVELOPE PROVIDED. You may revoke your proxy or change your vote at any time before the LRE special meeting. If your LRE common units are held in the name of a bank, broker, nominee or other record holder, please follow the instructions on the voting instruction card furnished to you by such record holder.

We urge you to read the accompanying proxy statement/prospectus, including all documents included in or incorporated by reference into the accompanying proxy statement/prospectus, and its annexes carefully and in their entirety. If you have any questions concerning the merger, the merger agreement, the advisory, non-binding vote on the merger-related compensation payments that may become payable to certain of LRE’s named executive officers in connection with the merger, the adjournment vote, the LRE special meeting or the accompanying proxy statement/prospectus, would like additional copies of the accompanying proxy statement/prospectus or need help voting your LRE common units, please contact LRE’s proxy solicitor.

The Solicitation Agent for the Special Meeting is:
 
Morrow & Co., LLC
470 West Avenue — 3^rd Floor
Stamford, CT 06902
 
Banks and Brokerage Firms, please call (203) 658-9400

Unitholders, please call toll free (855) 264-1296

TABLE OF CONTENTS

ADDITIONAL INFORMATION

This proxy statement/prospectus incorporates by reference important business and financial information about Vanguard and LRE from other documents filed with the Securities and Exchange Commission (the “SEC”) that are not included in or delivered with this proxy statement/prospectus. See “Where You Can Find More Information.”

Documents incorporated by reference are available to you without charge upon written or oral request. You can obtain any of these documents by requesting them in writing or by telephone from the appropriate party at the following addresses and telephone numbers.

Vanguard Natural Resources, LLC Attention: Investor Relations 5847 San Felipe, Suite 3000 Houston, Texas 77057 (832) 327-2255 investorrelations@vnrllc.com		LRR Energy, L.P. Attention: Investor Relations Heritage Plaza 1111 Bagby Street Suite 4600 Houston, Texas 77002 (713) 292-9510

To receive timely delivery of the requested documents in advance of the LRE special meeting, you should make your request no later than September 28, 2015.

ABOUT THIS DOCUMENT

This proxy statement/prospectus, which forms part of a registration statement on Form S-4 filed with the SEC by Vanguard (File No. 333-204696), constitutes a prospectus of Vanguard under Section 5 of the Securities Act of 1933, as amended (the “Securities Act”), with respect to the Vanguard common units to be issued pursuant to the merger agreement. This proxy statement/prospectus also constitutes a notice of meeting and a proxy statement under Section 14(a) of the Securities Exchange Act of 1934, as amended (the “Exchange Act”), with respect to the LRE special meeting, at which LRE unitholders will be asked to consider and vote on, among other matters, a proposal to approve the merger agreement and the transactions contemplated thereby.

You should rely only on the information contained in or incorporated by reference into this proxy statement/prospectus. No one has been authorized to provide you with information that is different from that contained in, or incorporated by reference into, this proxy statement/prospectus. This proxy statement/prospectus is dated September 3, 2015. The information contained in this proxy statement/prospectus is accurate only as of that date or, in the case of information in a document incorporated by reference, as of the date of such document, unless the information specifically indicates that another date applies. Neither the mailing of this proxy statement/prospectus to LRE unitholders nor the issuance by Vanguard of its common units pursuant to the merger agreement will create any implication to the contrary.

This proxy statement/prospectus does not constitute an offer to sell, or a solicitation of an offer to buy, any securities, or the solicitation of a proxy, in each case, in any jurisdiction in which, or from any person to whom, it is unlawful to make any such offer or solicitation in such jurisdiction.

The information concerning Vanguard contained in this proxy statement/prospectus or incorporated by reference has been provided by Vanguard, and the information concerning LRE contained in this proxy statement/prospectus or incorporated by reference has been provided by LRE.

TABLE OF CONTENTS

TABLE OF CONTENTS

QUESTIONS AND ANSWERS			1
SUMMARY			10
The Parties			10
The Merger			10
Merger Consideration			10
Treatment of LRE Restricted Units			11
LRE Special Unitholder Meeting; Unitholders Entitled to Vote; Vote Required			11
LRE’s Reasons for the Merger; Recommendation of LRE GP’s Board of Directors and LRE GP’s Conflicts Committee			12
Voting and Support Agreement			12
Termination and Continuing Obligations Agreement			13
Registration Rights Agreement			13
Opinions of the Financial Advisor to the LRE GP Board of Directors			14
Opinions of the Financial Advisor to the LRE GP Conflicts Committee			15
Vanguard Unitholder Approval is Not Required			15
Ownership of Vanguard After the Merger			15
Interests of Directors and Executive Officers of LRE GP in the Merger			16
Risks Relating to the Merger and Ownership of Vanguard Common Units			16
Material U.S. Federal Income Tax Consequences of the Merger			17
Accounting Treatment of the Merger			18
Listing of Vanguard Common Units; Delisting and Deregistration of LRE Common Units			18
No Appraisal Rights			18
Conditions to Consummation of the Transactions Contemplated by the Merger Agreement			18
Regulatory Approvals and Clearances Required for the Merger			19
No Solicitation by LRE of Alternative Proposals			19
Change in LRE GP Board Recommendation			20
Termination of the Merger Agreement			21
Expenses			21
Termination Fee			22
Comparison of Rights of Vanguard Common Unitholders and LRE Unitholders			22
Litigation Relating to the Merger			22
Litigation Relating to the Eagle Rock Merger			23
Recent Developments			24
Selected Historical Consolidated Financial Data of Vanguard			26
Selected Historical Consolidated Financial Data of LRE			32
Selected Unaudited Pro Forma Combined Financial Information			36
Unaudited Comparative Per Unit Information			38
Comparative Unit Prices and Distributions			41

TABLE OF CONTENTS

RISK FACTORS			44
Risk Factors Relating to the Merger			44
Risk Factors Relating to the Ownership of Vanguard Common Units			51
CAUTIONARY STATEMENT REGARDING FORWARD-LOOKING STATEMENTS			58
THE PARTIES			60
THE LRE SPECIAL MEETING			62
PROPOSAL 1: THE MERGER			67
Effect of the Merger			67
Background of the Merger			67
Recommendation of LRE GP’s Board of Directors and Its Reasons for the Merger			76
Reasons of LRE GP’s Board of Directors for Consenting to the Eagle Rock Merger			79
Recommendation of the LRE GP Conflicts Committee and Its Reasons for the Merger			82
Reasons of the LRE GP Conflicts Committee for Consenting to the Eagle Rock Merger			87
Opinions of the Financial Advisor to the LRE GP Board of Directors			89
Opinions of the Financial Advisor to the LRE GP Conflicts Committee			102
Voting and Support Agreement			123
Registration Rights Agreement			126
Termination and Continuing Obligations Agreement			126
Unaudited Prospective Financial and Operating Information of LRE and Vanguard			126
Vanguard’s Reasons for the Merger			131
Interests of Directors and Executive Officers of LRE GP in the Merger			131
No Appraisal Rights			134
Accounting Treatment of the Merger			134
Regulatory Approvals and Clearances Required for the Merger			134
Listing of Vanguard Common Units			134
Delisting and Deregistration of LRE Common Units			134
Vanguard Unitholder Approval is Not Required			134
Ownership of Vanguard After the Merger			134
Restrictions on Sales of Vanguard Common Units Received in the Merger			135
Board of Directors and Executive Officers Following the Merger			135
Litigation Relating to the Merger			135
THE MERGER AGREEMENT			137
The Merger			137
Effective Time; Closing			137
Merger Consideration			138
Treatment of LRE Restricted Units			138
Adjustments to Prevent Dilution			138
Withholding			138
Distributions			139
Conditions to Consummation of the Transactions Contemplated by the Merger Agreement			139

TABLE OF CONTENTS

LRE Unitholder Approval			142
No Solicitation by LRE of Alternative Proposals			143
Change in LRE GP Board Recommendation			144
Regulatory Matters			145
Termination of the Merger Agreement			146
Termination Fee			147
Expenses			148
Conduct of Business Pending the Consummation of the Transactions Contemplated by the Merger Agreement			148
Indemnification; Directors’ and Officers’ Insurance			151
Financing Matters			152
Amendment of Merger Agreement			152
Remedies; Specific Performance			152
Representations and Warranties			153
Additional Agreements			154
VANGUARD NATURAL RESOURCES, LLC UNAUDITED PRO FORMA COMBINED FINANCIAL INFORMATION			155
MATERIAL U.S. FEDERAL INCOME TAX CONSEQUENCES OF THE MERGER			195
Tax Opinions Required as a Condition to Closing			195
Assumptions Related to the U.S. Federal Income Tax Treatment of the Merger			196
U.S. Federal Income Tax Treatment of the Merger			197
Tax Consequences of the Merger to LRE			197
Tax Consequences of the Merger to LRE Common Unitholders			198
Tax Basis and Holding Period of the Vanguard Common Units Received			199
Effect of Termination of LRE’s Tax Year at Closing of Merger			199
Tax Consequences of the Merger to Vanguard and Its Unitholders			199
MATERIAL U.S. FEDERAL INCOME TAX CONSEQUENCES OF VANGUARD COMMON UNIT OWNERSHIP			200
Partnership Status			201
Limited Partner Status			202
Tax Consequences of Unit Ownership			202
Tax Treatment of Operations			207
Disposition of Common Units			212
Uniformity of Units			214
Tax-Exempt Organizations and Other Investors			215
Administrative Matters			215
State, Local, Foreign and Other Tax Considerations			218
DESCRIPTION OF VANGUARD COMMON UNITS			220
Where Common Units Are Traded			220
Issuance of Additional Units			220
Voting Rights			220

TABLE OF CONTENTS

Transfer Agent and Registrar			220
Transfer of Common Units			221
Summary of Limited Liability Company Agreement			221
COMPARISON OF RIGHTS OF VANGUARD COMMON UNITHOLDERS AND LRE UNITHOLDERS			222
Purpose			222
Outstanding Units			222
Issuance of Additional Securities			223
Distributions of Available Cash			223
Distributions of Cash upon Liquidation			226
Merger, Sale or Other Disposition of Assets			228
Election of Directors			229
Meetings; Voting; Voting Rights			229
Withdrawal or Removal of the General Partner; Election of General Partner			232
Transfer of General Partner Interests			234
No or Limited Preemptive Right			234
Limited Call Right			234
Amendment of Limited Liability Company Agreement or Partnership Agreement			235
Indemnification			239
Fiduciary Duties; Conflicts of Interest			240
Anti-Takeover Provisions			242
Dissolution			244
Transfer of Units; Status as Member, Limited Partner or Assignee			244
PROPOSAL 2: ADVISORY VOTE ON MERGER-RELATED NAMED EXECUTIVE OFFICER COMPENSATION			246
PROPOSAL 3: ADJOURNMENT OF THE LRE SPECIAL MEETING			247
LEGAL MATTERS			248
EXPERTS			249
WHERE YOU CAN FIND MORE INFORMATION			250
ANNEX A: Purchase Agreement and Plan of Merger			A-1
ANNEX B: Amended and Restated Voting and Support Agreement			B-1
ANNEX C: Opinion of Tudor, Pickering, Holt & Co. Advisors, LLC, dated April 20, 2015			C-1
ANNEX D: Opinion of Tudor, Pickering, Holt & Co. Advisors, LLC, dated May 21, 2015			D-1
ANNEX E: Opinion of Simmons & Company International, dated April 20, 2015			E-1
ANNEX F: Opinion of Simmons & Company International, dated May 20, 2015			F-1

TABLE OF CONTENTS

QUESTIONS AND ANSWERS

Set forth below are questions that you, as a unitholder of LRE, may have regarding the merger, the vote on the merger, the advisory, non-binding vote on the merger-related compensation payments that may become payable to certain of LRE’s named executive officers in connection with the merger, the adjournment proposal and the LRE special meeting, and brief answers to those questions. You are urged to read carefully this proxy statement/prospectus and the other documents referred to in this proxy statement/prospectus in their entirety, including the merger agreement, which is attached as Annex A to this proxy statement/prospectus, and the documents contained in and incorporated by reference into this proxy statement/prospectus, because this section may not provide all of the information that is important to you with respect to the merger and the LRE special meeting. You may obtain a list of the documents incorporated by reference into this proxy statement/prospectus in the section titled “Where You Can Find More Information.”

In the merger, Vanguard will issue Vanguard common units as the consideration to be paid to holders of LRE common units. This document is being delivered to you as both a proxy statement of LRE and a prospectus of Vanguard in connection with the merger. It is the proxy statement by which the board of directors of LRE GP is soliciting proxies from you to vote on the approval of the merger agreement and the transactions contemplated thereby at the LRE special meeting or at any adjournment or postponement of the LRE special meeting. It is also the prospectus by which Vanguard will issue Vanguard common units to you in the merger.

Your vote is important. We encourage you to vote as soon as possible.

TABLE OF CONTENTS

TABLE OF CONTENTS

The approval of the proposal to approve the merger agreement and the transactions contemplated thereby by LRE unitholders is a condition to the obligations of LRE and Vanguard to complete the transactions contemplated by the merger agreement. Neither the approval (on an advisory, non-binding basis) of the merger-related compensation proposal nor the approval of the proposal to adjourn is a condition to the obligations of LRE or Vanguard to complete the transactions contemplated by the merger agreement.

TABLE OF CONTENTS

Simultaneously with the execution of the merger agreement, Vanguard entered into a Voting and Support Agreement (the “original support agreement”) with each of LRR A, LRR B and LRR C, as holders of certain of the issued and outstanding LRE common units (collectively, the “Holders”), LRE, LRE GP, and, solely for certain restrictions on the sale of Vanguard common units, LRM, LRR II-A and LRR II-C. On May 21, 2015, in connection with the execution of the Eagle Rock merger agreement, the parties to the original support agreement entered into an Amended and Restated Voting and Support Agreement (the “amended and restated support agreement”). Pursuant to the amended and restated support agreement, the Holders have agreed to vote all of their LRE common units in favor of the merger agreement and to take certain other specified actions in furtherance of the merger. Collectively, the Holders hold common units representing approximately 30.5% of the votes of LRE’s outstanding common units as of August 27, 2015.

At the close of business on August 28, 2015, there were 28,074,433 common units outstanding, all of which are entitled to be voted at the LRE special meeting.

TABLE OF CONTENTS

Even if you plan to attend the LRE special meeting in person, your plans may change, thus you are encouraged to submit your proxy as described above so that your vote will be counted if you later decide not to attend the LRE special meeting.

If your LRE common units are held by a broker, bank, nominee or other holder of record, also known as holding units in “street name,” you should receive instructions from the broker, bank, nominee or other holder of record that you must follow in order to have your LRE common units voted. Please review such instructions to determine whether you will be able to submit your proxy via Internet or by telephone. The deadline for submitting your proxy by telephone or electronically through the Internet is 11:59 p.m. Eastern Time October 4, 2015 (the “Telephone/Internet deadline”).

If you do not provide voting instructions to your broker, your LRE common units will not be voted on any proposal on which your broker does not have discretionary authority to vote. This is referred to in this proxy statement/prospectus and in general as a broker non-vote. Because the only proposals for consideration at the LRE special meeting are non-discretionary proposals, it is not expected that there will be any broker non-votes at the LRE special meeting. If there are any broker non-votes, they will be counted as units that are present and entitled to be voted for purposes of determining the presence of a quorum, but the broker or other nominee will not be able to vote on those matters for which specific authorization is required. Under the current rules of the NYSE, brokers do not have discretionary authority to vote on the proposal to approve the merger agreement and the transactions contemplated thereby. A broker non-vote (if any) will have the same effect as a vote cast “AGAINST” (i) approval of the merger agreement and the transactions contemplated thereby, (ii) approval of the merger-related compensation proposal and (iii) approval of the adjournment proposal.

TABLE OF CONTENTS

If you hold your LRE common units through a broker or other nominee, you must follow the directions you receive from your broker or other nominee in order to revoke your proxy or change your voting instructions.

TABLE OF CONTENTS

A joint proxy statement/prospectus will be mailed to unitholders of Vanguard and Eagle Rock in connection with the Eagle Rock merger. The Eagle Rock merger is a transaction separate and apart from the merger, and the completion of the Eagle Rock merger is not a condition to the completion of the merger, and the completion of the merger is not a condition to the completion of the Eagle Rock merger.

TABLE OF CONTENTS

Please read “Risk Factors — Risk Factors Relating to the Merger” and “Material U.S. Federal Income Tax Consequences of the Merger — Tax Consequences of the Merger to LRE Common Unitholders.”

TABLE OF CONTENTS

At the effective time of the merger, LRE will be treated as a terminated partnership under Section 708 of the Code. Therefore, as a result of the merger, LRE’s taxable year will end as of the date of the merger, and LRE will be required to file a final U.S. federal income tax return for the taxable year ending on the date the merger is effective. LRE expects to furnish a Schedule K-1 to each LRE unitholder, and Vanguard expects to furnish a Schedule K-1 to each Vanguard unitholder, within 90 days of the closing of Vanguard’s taxable year on December 31, 2015.

If you hold units through a broker or other nominee, please instruct your broker or nominee to vote your LRE common units by following the instructions that the broker or nominee provides to you with these materials.

TABLE OF CONTENTS

SUMMARY

This summary highlights selected information from this proxy statement/prospectus. You are urged to read carefully the entire proxy statement/prospectus and the other documents referred to in this proxy statement/prospectus because the information in this section does not provide all the information that might be important to you with respect to the merger agreement, the merger and the other matters being considered at the LRE special meeting. See “Where You Can Find More Information.” Each item in this summary refers to the page of this proxy statement/prospectus on which that subject is discussed in more detail.

The Parties (See page 60)

Vanguard Natural Resources, LLC (“Vanguard”) is a Delaware limited liability company with common units traded on the NASDAQ Global Select Market (“NASDAQ”) under the symbol “VNR.” Vanguard is an independent energy company focused on the acquisition, exploitation and development of mature, long-lived oil and natural gas properties in the United States. Vanguard’s properties and oil and natural gas reserves are located primarily in nine operating basins in Wyoming, Colorado, Texas, New Mexico, Mississippi, Montana, Arkansas, Oklahoma and North Dakota. Vanguard’s principal executive offices are located at 5847 San Felipe, Suite 3000, Houston, Texas 77057, and its telephone number is (832) 327-2255.

LRR Energy, L.P. (“LRE”) is a Delaware limited partnership formed in April 2011 by Lime Rock Management LP (“LRM”), an affiliate of Lime Rock Resources A, L.P. (“LRR A”), Lime Rock Resources B, L.P. (“LRR B”) and Lime Rock Resources C, L.P. (“LRR C” and, together with LRR A and LRR B, “Fund I”), to operate, acquire, exploit and develop producing oil and natural gas properties in North America with long-lived, predictable production profiles. LRE’s properties consist of mature, low-risk onshore oil and natural gas reservoirs with long-lived, predictable production profiles located across three diverse producing regions: (i) the Permian Basin region in West Texas and Southeast New Mexico, (ii) the Mid-Continent region in Oklahoma and East Texas and (iii) the Gulf Coast region in Texas. LRE’s common units are traded on the NYSE under the symbol “LRE”. LRE GP, LLC, a Delaware limited liability company (“LRE GP”), is LRE’s general partner. LRE’s principal executive offices are located at Heritage Plaza, 1111 Bagby Street, Suite 4600, Houston, Texas 77002, and its telephone number is (713) 292-9510.

Lighthouse Merger Sub, LLC (“Merger Sub”) is a Delaware limited liability company and wholly owned subsidiary of Vanguard. Merger Sub was created for purposes of the merger and has not carried on any activities to date, other than activities incidental to its formation or undertaken in connection with the transactions contemplated by the merger agreement.

Each of LRM, LRR A, LRR B, LRR C, Lime Rock Resources II-A, L.P. (“LRR II-A”) and Lime Rock Resources II-C, L.P. (“LRR II-C”) are Delaware limited partnerships and affiliates of LRE that own limited liability company interests in LRE GP.

The Merger (See page 67)

Subject to the terms and conditions of the merger agreement and in accordance with Delaware law, the merger agreement provides for the merger of Merger Sub with and into LRE, with LRE continuing as the surviving entity, and, at the same time, the purchase by Vanguard of all of the outstanding limited liability company interests in LRE GP, resulting in both LRE and LRE GP becoming wholly owned subsidiaries of Vanguard.

Merger Consideration (See page 138)

The merger agreement provides that, at the effective time of the merger (the “effective time”), each LRE common unit issued and outstanding immediately prior to the effective time will be converted into the right to receive 0.550 Vanguard common units. Any LRE common units that are owned by LRE or Vanguard or any of their respective subsidiaries at the effective time will be cancelled and cease to exist, without any conversion or payment of consideration in respect thereof.

TABLE OF CONTENTS

Treatment of LRE Restricted Units (See page 138)

Under the merger agreement, each LRE restricted unit that is outstanding and unvested immediately prior to the effective time will, at the effective time, become fully vested and the restrictions with respect thereto will lapse and such LRE restricted unit be deemed to be an LRE common unit for purposes of the merger.

LRE Special Unitholder Meeting; Unitholders Entitled to Vote; Vote Required (See page 62)

Meeting.  The special meeting will be held at Two Allen Center, 1200 Smith Street, the Forum Assembly Room on the 12th Floor, Houston, TX 77002 on October 5, 2015 at 10:00 a.m., local time. At the LRE special meeting, LRE unitholders will be asked to vote on the following proposals:

Record Date.  Only LRE unitholders of record at the close of business on August 28, 2015, the record date for the determination of holders entitled to notice of and to vote at the LRE special meeting, will be entitled to receive notice of and to vote at the LRE special meeting. As of the close of business on August 28, 2015, there were 28,074,433 LRE common units outstanding and entitled to be voted at the meeting. Each holder of LRE common units is entitled to one vote for each unit owned as of the record date.

Required Vote.  To approve the merger agreement and the transactions contemplated thereby, the holders, as of the record date of the special meeting, of a majority of the outstanding LRE common units must vote in favor of such proposal. LRE cannot complete the merger unless its unitholders approve the merger agreement and the transactions contemplated thereby. Simultaneous with the execution of the merger agreement, certain affiliates of LRE, as holders of certain of the issued and outstanding LRE common units, have entered into an amended and restated voting and support agreement with Vanguard, pursuant to which they have agreed to vote all of their LRE common units in favor of the approval of the merger agreement and to take other actions in furtherance of the transactions contemplated by the merger agreement. Collectively, these LRE unitholders hold common units representing approximately 30.5% of the votes of LRE’s outstanding common units as of August 27, 2015. Because approval of this proposal is based on the affirmative vote of the holders of a majority of the outstanding LRE common units, an LRE unitholder’s failure to vote, an abstention from voting or the failure of an LRE unitholder who holds his or her units in “street name” through a broker or other nominee to give voting instructions to such broker or other nominee will have the same effect as a vote cast “AGAINST” approval of the merger agreement and the transactions contemplated thereby.

To approve (on an advisory, non-binding basis) the proposal regarding the merger-related compensation payments that may become payable to certain of LRE’s named executive officers in connection with the merger, the holders, as of the record date of the special meeting, of a majority of the outstanding LRE common units must vote in favor of such proposal. Because approval of this proposal is based on the affirmative vote of the holders of a majority of the outstanding LRE common units, an LRE unitholder’s failure to vote, an abstention from voting or the failure of an LRE unitholder who holds his or her units in “street name” through a broker or other nominee to give voting instructions to such broker or other nominee will have the same effect as a vote cast “AGAINST” approval of the merger–related compensation payments.

To approve the adjournment of the LRE special meeting if necessary to solicit additional proxies if there are not sufficient votes to approve the merger agreement at the time of the special meeting if a quorum is present at, and if a limited partner vote is solicited on adjournment of, the meeting, the holders of a majority of the outstanding LRE common units must vote in favor of the proposal. If a quorum is not present at the meeting, the affirmative vote of the holders of a majority of the outstanding LRE common units present and

TABLE OF CONTENTS

entitled to be voted at such meeting represented either in person or by proxy is required to adjourn. Because approval of this proposal is based on the affirmative vote of the holders of a majority of the outstanding LRE common units if a quorum is present, if a limited partner vote is solicited, an LRE unitholder’s failure to vote, an abstention from voting or the failure of an LRE unitholder who holds his or her units in “street name” through a broker or other nominee to give voting instructions to such broker or other nominee will have the same effect as a vote cast “AGAINST” approval of this proposal.

Unit Ownership of and Voting by LRE GP’s Directors and Executive Officers.  At the close of business on the record date for the LRE special meeting, LRE GP’s directors and executive officers and their affiliates beneficially owned and had the right to vote 8,962,552 LRE common units at the LRE special meeting, which represents approximately 32% of the LRE common units entitled to be voted at the LRE special meeting. It is expected that LRE GP’s directors and executive officers will vote their units “FOR” the approval of the merger agreement and the transactions contemplated thereby, although none of them has entered into any agreement requiring them to do so.

LRE Unitholder Proposals.  Ownership of LRE common units does not entitle LRE common unitholders to make proposals at the LRE special meeting. The LRE partnership agreement gives LRE GP the right to make rules regarding the conduct of such meetings and only permits the limited partners of LRE to have the right to vote on matters they are entitled to vote on under the LRE partnership agreement or with respect to matters that LRE GP determines to submit to a vote of the limited partners of LRE. As a result, LRE GP may adopt a rule for such meetings that only LRE GP may make proposals at such meetings, and it is expected that LRE GP will adopt such a rule for the LRE special meeting.

LRE’s Reasons for the Merger; Recommendation of LRE GP’s Board of Directors and LRE GP’s Conflicts Committee (See pages 76 and 82)

The conflicts committee of the board of directors of LRE GP (the “LRE GP conflicts committee”) has determined that the merger agreement is advisable to and in the best interests of LRE and its unitholders who are not affiliates of LRE GP and has approved the merger agreement and recommended that the board of directors of LRE GP approve the merger agreement. Based upon, among other things, the recommendation of the LRE GP conflicts committee, the board of directors of LRE GP has determined that the merger agreement and the transactions contemplated thereby are in the best interests of LRE and its unitholders and recommends that LRE unitholders vote “FOR” the approval of the merger agreement and the transactions contemplated thereby.

In the course of reaching its decision to approve the merger agreement and the transactions contemplated by the merger agreement, the board of directors of LRE GP considered a number of factors in its deliberations in addition to the recommendation of the LRE GP conflicts committee. For a more complete discussion of these factors, see “Proposal 1: The Merger — Recommendation of LRE GP’s Board of Directors and Its Reasons for the Merger” and “Proposal 1: The Merger — Recommendation of the LRE GP Conflicts Committee and Its Reasons for the Merger.”

Voting and Support Agreement (See page 123)

Simultaneous with the execution of the merger agreement, Vanguard entered into a Voting and Support Agreement (the “original support agreement”) with each of LRR A, LRR B and LRR C, as holders of certain of the issued and outstanding LRE common units (collectively, the “Holders”), LRE, LRE GP, and, solely for certain restrictions on the sale of Vanguard common units, LRM, LRR II-A and LRR II-C (the “Non-Fund I GP Sellers”). On May 21, 2015, in connection with the execution of the Eagle Rock merger agreement, the parties to the original support agreement entered into an Amended and Restated Voting and Support Agreement (the “amended and restated support agreement”). Collectively, the Holders hold LRE common units representing approximately 30.5% of the votes of LRE’s outstanding common units as of August 27, 2015.

In accordance with the amended and restated support agreement, the Holders have agreed, among other things, subject to a change in recommendation by the board of directors of LRE GP, to vote or cause to be voted all of their units, including LRE common units owned by such Holders, in favor of the merger and the approval of the merger agreement and against alternative proposals or other proposals made in opposition to

TABLE OF CONTENTS

approval of the merger agreement and other actions or transactions which might materially impede or interfere with the merger or the transactions contemplated by the merger agreement. The Holders also agreed to provide Vanguard with an irrevocable proxy over all of their LRE common units, which will empower Vanguard, subject to the terms of the amended and restated support agreement, to vote those units in favor of the merger and the transactions contemplated thereby on behalf of the Holders. The foregoing obligations will terminate upon the earliest to occur of (a) the consummation of the merger and (b) the valid termination of the merger agreement in accordance with its terms.

The Holders have also agreed to certain restrictions under the amended and restated support agreement, including but not limited to: (i) a restriction on transferring more than 15% of their LRE common units prior to the earlier of the completion of the merger and the valid termination of the merger agreement in accordance with its terms and (ii) a restriction on soliciting or encouraging alternative proposals. Furthermore, the Holders agreed to promptly notify Vanguard of any alternative proposal that they receive and to keep Vanguard reasonably informed on the material developments of any such alternative proposals. For a period beginning at the effective time of the merger and continuing for a period of 90 days thereafter, the Holders and the Non-Fund I GP Sellers have also agreed not to sell, contract to sell, transfer or otherwise dispose of any Vanguard common units (or any security exercisable or exchangeable for Vanguard common units) received in the transactions contemplated by the merger agreement, provided that, on each trading day during such period, the Holders and the Non-Fund I GP Sellers may sell, contract to sell, transfer or otherwise dispose of an aggregate number of Vanguard common units (or any security exercisable or exchangeable for Vanguard common units), on a daily basis, not to exceed 10% of the average daily trading volume of Vanguard common units during the four weeks immediately prior to the first day of the calendar month in which such transaction occurs. Vanguard and the Holders have also agreed to a mutual two-year non-solicitation of employees commencing at the effective time of the merger.

For a more complete discussion of the amended and restated support agreement, see “Proposal 1: The Merger — Voting and Support Agreement.”

Termination and Continuing Obligations Agreement (See page 126)

As a condition to closing of transactions contemplated under the merger agreement, the parties have agreed to execute and deliver a Termination and Continuing Obligations Agreement (the “termination agreement”) substantially in the form attached as an exhibit to the merger agreement. Pursuant to the termination agreement, (i) the omnibus agreement among LRE, LRE GP, LRE Operating, LLC, a Delaware limited liability company and wholly owned subsidiary of LRE (“OLLC”), the Holders, LRR GP, LLC, a Delaware limited liability company and the ultimate general partner of each of the Holders, and LRM, will be terminated and (ii) the Holders, severally and in proportion to each entity's property contributor percentage, will agree to indemnify LRE, LRE GP, OLLC and all of their respective subsidiaries from and against any losses arising out of any income tax liabilities attributable to the ownership or operation of the oil and natural gas properties owned or leased by any of LRE, LRE GP, OLLC or their respective subsidiaries prior to the closing of the LRE's initial public offering. The indemnification obligations of the Holders under the termination agreement will survive until the first anniversary of the closing date of the merger. See “Proposal 1: The Merger — Termination and Continuing Obligations Agreement.”

Registration Rights Agreement (See page 126)

Simultaneous with the execution of the merger agreement, Vanguard entered into a Registration Rights Agreement (the “original registration rights agreement”) with the Holders and Non-Fund I GP Sellers. On May 21, 2015, in connection with the execution of the Eagle Rock merger agreement, the parties to the original registration rights agreement entered into an Amended and Restated Registration Rights Agreement (the “amended and restated registration rights agreement”). Pursuant to the amended and restated registration rights agreement, among other things, (i) no later than the 14^th day following the closing date of the merger, Vanguard will file with the SEC either (a) a shelf registration statement with respect to the public resale of the Vanguard common units received by the Holders and Non-Fund I GP Sellers as consideration in the merger and the acquisition of LRE GP or (b) a post-effective amendment to Vanguard’s existing automatic shelf registration statement on Form S-3, (ii) the Holders and the Non-Fund I GP Sellers will have the right to participate in future underwritten public offerings of Vanguard common units and (iii) subject to certain

TABLE OF CONTENTS

conditions, Vanguard will be obligated to initiate an underwritten offering of the Vanguard common units received by the Holders and the Non-Fund I GP Sellers as consideration in the merger and the acquisition of LRE GP. For a more complete discussion of the registration rights agreement, see “Proposal 1: The Merger — Registration Rights Agreement.”

Opinions of the Financial Advisor to the LRE GP Board of Directors (See page 89)

The board of directors of LRE GP retained Tudor, Pickering, Holt & Co. Advisors, LLC (“TPH”) as its exclusive financial advisor to provide financial advice and assistance to the board and to provide an opinion to the board in connection with the merger. TPH evaluated the fairness, from a financial point of view, of the merger consideration to be received in the merger by the holders of LRE common units. At a meeting of the board of directors of LRE GP held on April 20, 2015, at the request of the board, TPH orally rendered its opinion to the board that, as of April 20, 2015, based upon and subject to the assumptions, qualifications, limitations and other matters considered by TPH in connection with the preparation of its opinion, the merger consideration to be received in the merger by the holders of LRE common units pursuant to the merger agreement was fair, from a financial point of view, to such unitholders. TPH subsequently confirmed its opinion in writing to the board of directors of LRE GP (the “LRE Opinion”).

Pursuant to the merger agreement, Vanguard’s entering into and performing the Eagle Rock merger agreement and consummating the transactions contemplated by the Eagle Rock merger agreement (the “Eagle Rock Transactions”), including the Eagle Rock merger, required the prior consent of the board of directors of LRE GP. Accordingly, in connection with its negotiation of the Eagle Rock merger agreement, Vanguard sought such consent of the board of directors of LRE GP (the “Consent”). The board of directors of LRE GP retained TPH as its exclusive financial advisor to provide financial advice and assistance to the board and to provide an opinion to the board in connection with the board’s consideration of the Consent. TPH evaluated the fairness, from a financial point of view, to Vanguard, giving pro forma effect to the consummation of the transactions contemplated by the merger agreement (the “LRE Transactions”) (“New Vanguard”), of the consideration to be paid by New Vanguard pursuant to the Eagle Rock merger agreement (the “Eagle Rock merger consideration”). At a meeting of the board of directors of LRE GP held on May 21, 2015, at the request of the board, TPH orally rendered its opinion to the board that, as of May 21, 2015, based upon and subject to the assumptions, qualifications, limitations and other matters considered by TPH in connection with the preparation of its opinion, the Eagle Rock merger consideration to be paid by New Vanguard pursuant to the Eagle Rock merger agreement was fair, from a financial point of view, to New Vanguard. TPH subsequently confirmed its opinion in writing to the board of directors of LRE GP (the “Eagle Rock Opinion”).

The full text of the LRE Opinion, dated April 20, 2015, and the Eagle Rock Opinion, dated May 21, 2015, each of which sets forth, among other things, the assumptions made, procedures followed, matters considered, and qualifications and limitations of the review undertaken by TPH in rendering its opinions, are attached as Annex C and Annex D to this proxy statement/prospectus and are incorporated herein by reference. The summary of the TPH opinions set forth in this proxy statement/prospectus is qualified in its entirety by reference to the full text of the opinions. LRE unitholders are urged to read each TPH opinion carefully and in its entirety. TPH provided its opinions for the information and assistance of the board of directors of LRE GP in connection with (i) its consideration of the merger and (ii) its consideration of the Consent. Neither TPH opinion nor the summaries thereof, nor the related analyses disclosed in this proxy statement/prospectus, constitutes a recommendation as to how the board of directors of LRE GP, any holder of securities in LRE, Vanguard or Eagle Rock or any other person should act or vote with respect to the LRE Transactions, the Eagle Rock Transactions, the Consent or any other matter. TPH did not express any view on, and neither opinion addressed, any other term or aspect of the merger agreement, the LRE Transactions, the Eagle Rock merger agreement or the Eagle Rock Transactions. TPH did not express any opinion as to the price at which Vanguard common units, LRE common units or Eagle Rock common units will trade at any time or as to the impact of the LRE Transactions or the Eagle Rock Transactions on the solvency or viability of LRE, Vanguard or Eagle Rock or the ability of each of LRE, Vanguard or Eagle Rock to pay its obligations when they become due.

See “The Merger — Opinions of the Financial Advisor to the LRE GP Board of Directors” beginning on page 89. See also Annex C and Annex D to this proxy statement/prospectus.

TABLE OF CONTENTS

Opinions of the Financial Advisor to the LRE GP Conflicts Committee (See page 102)

In connection with the merger, Simmons & Company International (“Simmons”) delivered its opinion to the LRE GP conflicts committee to the effect that, as of April 20, 2015, and based upon and subject to the assumptions, limitations and qualifications set forth in its opinion, the terms of the merger contemplated by the merger agreement were fair from a financial point of view to the holders of common units of LRE other than LRM or affiliate entities (the “unaffiliated LRE unitholders”).

In connection with the LRE GP conflicts committee’s consideration of whether to consent to the Eagle Rock merger, Simmons delivered its opinion to the LRE GP conflicts committee to the effect that, as of May 20, 2015, and based upon and subject to the assumptions, limitations and qualifications set forth in its opinion, the terms of the Eagle Rock merger contemplated by the Eagle Rock merger agreement were fair from a financial point of view to the unaffiliated LRE unitholders.

The full text of Simmons’ written opinion, dated April 20, 2015, which sets forth assumptions made, procedures followed, matters considered and limitations on the review undertaken in connection with the opinion, is attached as Annex E.

The full text of Simmons’ written opinion, dated May 20, 2015, which sets forth assumptions made, procedures followed, matters considered and limitations on the review undertaken in connection with the opinion, is attached as Annex F.

Simmons’ opinion, dated April 20, 2015, was provided to the LRE GP conflicts committee in connection with the LRE GP conflicts committee’s consideration of the merger agreement, does not address any other aspect of the proposed merger agreement or the Eagle Rock merger and does not constitute a recommendation as to how any holder of interests in LRE or any other party to the merger or the Eagle Rock merger should vote or act with respect to the merger agreement, the Eagle Rock merger or any other matter. Simmons’ opinion, dated May 20, 2015, was provided to the LRE GP conflicts committee in connection with the LRE GP conflicts committee’s consideration of whether to consent to the Eagle Rock merger, does not address any other aspect of the proposed merger agreement, or the Eagle Rock merger, and does not constitute a recommendation as to how any holder of interests in LRE or any other party to the merger agreement or the Eagle Rock merger should vote or act with respect to the merger, the Eagle Rock merger or any other matter. See “The Merger — Opinions of the Financial Advisor to the LRE GP Conflicts Committee” beginning on page 102. See also Annex E and Annex F to this proxy statement/prospectus.

Vanguard Unitholder Approval is Not Required (See page 134)

Vanguard unitholders are not required to approve the merger agreement or approve the merger or the issuance of Vanguard common units in connection with the merger.

Ownership of Vanguard After the Merger (See page 134)

Vanguard will issue approximately 15.44 million Vanguard common units to former LRE unitholders (which does not include the 12,320 Vanguard common units to be issued to the former members of LRE GP) pursuant to the transactions contemplated by the merger agreement. Additionally, if the Eagle Rock merger is consummated, Vanguard will issue approximately 28.75 million Vanguard common units to former Eagle Rock unitholders pursuant to the transactions contemplated by the Eagle Rock merger agreement. Further, the number of Vanguard common units outstanding will increase after the date of this proxy statement/prospectus if Vanguard sells additional common units to the public.

If the Eagle Rock merger is consummated pursuant to the terms and conditions of the Eagle Rock merger agreement, based on the number of Vanguard common units outstanding as of August 27, 2015, immediately following the later to occur of the transactions contemplated by the merger agreement and the Eagle Rock merger agreement, Vanguard expects to have approximately 130.80 million Vanguard common units outstanding (including the 12,320 Vanguard common units issued to the members of LRE GP). Under this scenario, LRE unitholders would be expected to hold approximately 11.8% of the aggregate number of Vanguard common units outstanding immediately after the completion of the merger and the Eagle Rock merger.

TABLE OF CONTENTS

If, however, the Eagle Rock merger is not consummated pursuant to the terms and conditions of the Eagle Rock merger agreement, based on the number of Vanguard common units outstanding as of August 27, 2015, immediately following the completion of the merger, Vanguard expects to have approximately 102.05 million common units outstanding (including the 12,320 Vanguard common units issued to the members of LRE GP). Under this scenario, LRE unitholders would be expected to hold approximately 15.1% of the aggregate number of Vanguard common units outstanding immediately after the completion of the merger.

Interests of Directors and Executive Officers of LRE GP in the Merger (See page 131)

LRE GP’s directors and executive officers have financial interests in the merger that are different from, or in addition to, the interests of the LRE unitholders generally. Except as noted below, the members of the board of directors of LRE GP were aware of and considered these interests, among other matters, in evaluating and negotiating the merger agreement and the merger, and in recommending to LRE’s unitholders that the merger agreement be approved.

These interests include:

Risks Relating to the Merger and Ownership of Vanguard Common Units (See page 44)

LRE unitholders should consider carefully all the risk factors together with all of the other information contained in or incorporated by reference in this proxy statement/prospectus before deciding how to vote. Risks relating to the merger and ownership of Vanguard common units are described in the section titled “Risk Factors.” Some of these risks include, but are not limited to, those described below:

TABLE OF CONTENTS

Material U.S. Federal Income Tax Consequences of the Merger (See page 195)

Tax matters associated with the merger are complicated. The U.S. federal income tax consequences of the merger to an LRE unitholder will depend, in part, on such unitholder’s own personal tax situation. The tax discussions contained herein focus on the U.S. federal income tax consequences generally applicable to individuals who are residents or citizens of the United States that hold their LRE units as capital assets and acquired their LRE units in exchange for cash, and these discussions have only limited application to other unitholders, including those subject to special tax treatment. LRE unitholders are urged to consult their tax advisors for a full understanding of the U.S. federal, state, local and foreign tax consequences of the merger that will be applicable to them.

In connection with the merger, LRE expects to receive an opinion from Andrews Kurth LLP to the effect that (i) except to the extent that any cash received in lieu of fractional common units of Vanguard is treated as part of a sale, LRE will not recognize any income or gain as a result of the merger other than any gain resulting from any decrease in partnership liabilities pursuant to Section 752 of the Code; (ii) except to the extent that any cash received in lieu of fractional common units of Vanguard is treated as part of a sale, a holder of LRE common units who acquired his units in exchange for cash will not recognize any income or gain as a result of the merger other than any gain resulting from any actual or constructive distribution of cash, including as a result of any decrease in partnership liabilities pursuant to Section 752 of the Code; and (iii) at least 90% of the gross income of LRE for the most recent four complete calendar quarters ending before the Closing Date for which the necessary financial information is available is from sources treated as “qualifying income” within the meaning of Section 7704(d) of the Code.

In connection with the merger, Vanguard expects to receive an opinion from Paul Hastings LLP to the effect that (i) Vanguard will not recognize any income or gain as a result of the merger other than any gain resulting from any decrease in partnership liabilities pursuant to Section 752 of the Code; (ii) a holder of Vanguard common units will not recognize any gain or loss as a result of the merger other than any gain resulting from any decrease in partnership liabilities pursuant to Section 752 of the Code; and (iii) at least 90% of the combined gross income of each of Vanguard and LRE for the most recent four complete calendar

TABLE OF CONTENTS

quarters ending before the Closing Date for which the necessary financial information is available is from sources treated as “qualifying income” within the meaning of Section 7704(d) of the Code.

Opinions of counsel, however, are subject to certain limitations and are not binding on the Internal Revenue Service (“IRS”) and no assurance can be given that the IRS could not successfully assert a contrary position to the position of the opinions of counsel regarding the merger. In addition, such opinions will be based upon certain factual assumptions, representations, warranties and covenants made by the officers of Vanguard, LRE, LRE GP and their respective affiliates. Please read “Material U.S. Federal Income Tax Consequences of the Merger” for a more complete discussion of the U.S. federal income tax consequences of the merger.

Accounting Treatment of the Merger (See page 134)

In accordance with accounting principles generally accepted in the United States (“GAAP”) and in accordance with the Financial Accounting Standards Board’s Accounting Standards Codification Topic 805 — Business Combinations, Vanguard will account for the merger as an acquisition of a business.

Listing of Vanguard Common Units; Delisting and Deregistration of LRE Common Units (See page 134)

Vanguard common units are currently listed on the NASDAQ under the symbol “VNR.” It is a condition to closing that the Vanguard common units to be issued in the transactions contemplated by the merger agreement to LRE unitholders and LRE GP members be approved for listing on the NASDAQ, subject to official notice of issuance.

LRE common units are currently listed on the NYSE under the ticker symbol “LRE.” If the merger is completed, LRE common units will cease to be listed on the NYSE and will be deregistered under the Exchange Act.

No Appraisal Rights (See page 134)

Appraisal rights are not available in connection with the merger under the Delaware LP Act or under the LRE partnership agreement.

Conditions to Consummation of the Transactions Contemplated by the Merger Agreement (See page 139)

Vanguard and LRE currently expect to complete the transactions contemplated by the merger agreement in October 2015, subject to a majority of LRE unitholders voting in favor of approving the merger agreement and to the satisfaction or waiver of the other conditions to the transactions contemplated by the merger agreement described below.

As more fully described in this proxy statement/prospectus, each party’s obligation to complete the transactions contemplated by the merger agreement depends on a number of customary closing conditions being satisfied or, where legally permissible, waived, including the following:

TABLE OF CONTENTS

The obligation of Vanguard to effect the transactions contemplated by the merger agreement is subject to the satisfaction or waiver of the following additional conditions:

The obligation of the sellers of LRE GP and LRE to effect the transactions contemplated by the merger agreement is subject to the satisfaction or waiver of the following additional conditions:

Regulatory Approvals and Clearances Required for the Merger (See page 134)

Vanguard and LRE are not required to file notifications with the Federal Trade Commission and the Antitrust Division of the Department of Justice or observe a mandatory pre-merger waiting period before completing the merger under the HSR Act. Vanguard and LRE cannot assure you, however, that other government agencies or private parties will not initiate actions to challenge the merger before or after it is completed.

No Solicitation by LRE of Alternative Proposals (See page 143)

Under the merger agreement, LRE has agreed that it will not, and will cause its subsidiaries and use reasonable best efforts to cause its and its subsidiaries’ directors, officers, employees, investment bankers, financial advisors, attorneys, accountants, agents and other representatives not to, directly or indirectly:

TABLE OF CONTENTS

In addition, the merger agreement requires LRE and its subsidiaries to cease and cause to be terminated any discussions or negotiations with any persons conducted prior to the execution of the merger agreement regarding an alternative proposal.

Notwithstanding these restrictions, the merger agreement provides that, under specified circumstances at any time prior to a majority of LRE unitholders voting in favor of approving the merger agreement, LRE may furnish information, including confidential information, with respect to it and its subsidiaries to, and participate in discussions or negotiations with, any third party that makes a written alternative proposal (which was not solicited after the execution of the merger agreement and that did not result from a violation of the no solicitation restrictions described above) that the board of directors of LRE GP believes is bona fide, and (after consultation with its financial advisors and outside legal counsel) that the board of directors of LRE GP determines in good faith constitutes or would reasonably be likely to lead to or result in a superior proposal.

LRE has also agreed in the merger agreement that it will promptly, and in any event within 24 hours after receipt, (i) advise Vanguard in writing of any alternative proposal (and any changes thereto) and the material terms and conditions of any such alternative proposal, including the identity of the person making such alternative proposal and (ii) provide Vanguard with copies of all written proposals or draft agreements received by LRE or any representative of LRE setting forth the terms and conditions of, or otherwise relating to, such alternative proposal. In addition, LRE will keep Vanguard reasonably informed of all material developments with respect to any such alternative proposals, offers, inquiries or requests (and promptly (and in no event later than 24 hours after receipt) provide Vanguard with copies of any additional written proposals received by LRE or that LRE has delivered to any third party making an alternative proposal that relate to such alternative proposal) and of the status of any such discussions or negotiations.

Change in LRE GP Board Recommendation (See page 144)

The merger agreement provides that the board of directors of LRE GP will not (i) withdraw, modify or qualify, in a manner adverse to Vanguard, the recommendation of the board of directors of LRE GP that LRE’s unitholders approve the merger agreement and the transactions contemplated thereby, including the merger, (ii) fail to include such recommendation in this proxy statement/prospectus or (iii) publicly approve or recommend, or publicly propose to approve or recommend, any alternative proposal. LRE taking or failing to take, as applicable, any of the actions described above is referred to as a “partnership change in recommendation.” The merger agreement also provides that the board of directors of LRE GP will not: (i) approve, adopt or recommend, or publicly propose to approve, adopt or recommend, or allow LRE or any of its subsidiaries to execute or enter into, any letter of intent, memorandum of understanding, agreement in principle, merger agreement, acquisition agreement, option agreement, joint venture agreement, partnership agreement or other similar contract or any tender or exchange offer providing for, with respect to, or in connection with any alternative proposal; (ii) fail to announce publicly within ten business days after a tender offer or exchange offer relating to the LRE common units has been commenced that the board of directors of LRE GP recommends rejection of such tender offer or exchange offer and reaffirming the recommendation of the board of directors of LRE GP that LRE’s unitholders approve the merger agreement and the transactions contemplated thereby, including the merger; or (iii) resolve, agree or publicly propose to, or permit LRE or any of its representatives to agree or publicly propose to, take any of the actions referred to in this paragraph.

Subject to the satisfaction of specified conditions in the merger agreement described under “The Merger Agreement — Change in LRE GP Board Recommendation,” the board of directors of LRE GP may, at any time prior to the approval of the merger agreement by the unitholders of LRE, effect a partnership change in recommendation in response to any bona fide alternative proposal if the board of directors of LRE GP determines, after consultation with its outside legal counsel and financial advisors, that such alternative proposal constitutes a superior proposal.

TABLE OF CONTENTS

Termination of the Merger Agreement (See page 146)

The merger agreement may be terminated at any time prior to the closing, whether before or after LRE unitholders have approved the merger agreement, as follows:

Expenses (See page 148)

Generally, all fees and expenses incurred in connection with the transactions contemplated by the merger agreement will be the obligation of the respective party incurring such fees and expenses, except that Vanguard and LRE will each pay one-half of the expenses incurred in connection with any HSR Act filing and the filing, printing and mailing of this proxy statement/prospectus.

In addition, following a termination of the merger agreement in specified circumstances, the non-terminating party would be required to pay all of the reasonably documented out-of-pocket expenses incurred by the terminating party in connection with the merger agreement and the transactions contemplated thereby, up to a maximum amount of $1,215,000.

TABLE OF CONTENTS

Termination Fee (See page 147)

Following termination of the merger agreement under specified circumstances, including (i) termination by Vanguard due to a partnership change in recommendation having occurred, (ii) termination by LRE in order to enter into a superior proposal or (iii) termination by either party after an alternative proposal was received by LRE, and LRE enters into an definitive agreement with respect to such alternative proposal within 12 months after the date of the merger agreement, LRE will be required to pay Vanguard a termination fee of $7,288,000. Following payment of the termination fee, LRE will not be obligated to pay any additional expenses incurred by Vanguard or its affiliates.

Comparison of Rights of Vanguard Common Unitholders and LRE Unitholders (See page 222)

LRE unitholders will own Vanguard common units following the completion of the merger, and their rights associated with those Vanguard common units will be governed by the Vanguard limited liability company agreement, which differs in a number of respects from the LRE partnership agreement, and the Delaware Limited Liability Company Act (the “Delaware LLC Act”).

Litigation Relating to the Merger (See page 135)

A putative class action was filed on June 3, 2015 in connection with the merger by a purported LRE unitholder (the “Delaware State Plaintiff”) against LRE, LRE GP, the members of the LRE GP board of directors, Vanguard, Merger Sub and the other parties to the merger agreement (the “Original Defendants”). The lawsuit was styled Barry Miller v. LRR Energy, L.P. et al., Case No. 11087-VCG, in the Court of Chancery of the State of Delaware (the “Delaware State Lawsuit”). On July 23, 2015, the Delaware State Plaintiff voluntarily dismissed the Delaware State Lawsuit without prejudice.

On July 10, 2015 and July 13, 2015, two additional purported LRE unitholders (the “Texas State Plaintiffs”) filed putative class action lawsuits against the Original Defendants. These lawsuits were styled (a) Christopher Tiberio v. Eric Mullins et al., Cause No. 2015-39864, in the District Court of Harris County, Texas, 334th Judicial District; and (b) Eddie Hammond v. Eric Mullins et al., Cause No. 2015-40154, in the District Court of Harris County, Texas, 295th Judicial District (the “Texas State Lawsuits”). On July 28, 2015, the Texas State Lawsuits were nonsuited without prejudice.

On July 14, 2015, another purported LRE unitholder (the “Texas Federal Plaintiff”) filed a putative class action lawsuit against the Original Defendants. This lawsuit was styled Ronald Krieger v. LRR Energy, L.P. et al., Civil Action No. 4:15-cv-2017, in the United States District Court for the Southern District of Texas, Houston Division (the “Texas Federal Lawsuit”). On July 17, 2015, the Texas Federal Plaintiff voluntarily dismissed the Texas Federal Lawsuit without prejudice.

On August 18, 2015, another purported LRE unitholder (the “Plaintiff”) filed a putative class action lawsuit against the members of the LRE GP board of directors, Vanguard, and Merger Sub (the “Defendants”). This lawsuit is styled Robert Hurwitz v. Eric Mullins et al., Civil Action No. 1:15-cv-00711-UNA, in the United States District Court for the District of Delaware (the “Lawsuit”).

The Lawsuit alleges that the Defendants violated Sections 14(a) and/or 20(a) of the Exchange Act and Rule 14a-9 promulgated thereunder. In general, the Plaintiff alleges that the proxy statement/prospectus fails, among other things, to disclose allegedly material details concerning (i) the background of the merger, (ii) Simmons’ and TPH’s analysis of the merger, (iii) LRE’s and Vanguard’s financial and operational projections, and (iv) certain alleged conflicts of interest.

The Plaintiff seeks, among other relief, to enjoin the merger, or rescind the merger in the event it is consummated, and an award of attorneys’ fees and costs.

The Plaintiff has not yet served the Defendants, and the Defendants’ date to answer, move to dismiss, or otherwise respond to the Lawsuit has not yet been set.

Vanguard and LRE cannot predict the outcome of the Lawsuit or any others that might be filed subsequent to the date of the filing of this proxy statement/prospectus; nor can Vanguard and LRE predict the amount of time and expense that will be required to resolve the Lawsuit. The Defendants believe the Lawsuit is without merit and intend to vigorously defend against it.

TABLE OF CONTENTS

Litigation Relating to the Eagle Rock Merger

On May 28, 2015 and June 10, 2015, alleged Eagle Rock unitholders (the “Eagle Rock State Plaintiffs”) filed two derivative and class action lawsuits against Eagle Rock, Eagle Rock GP, Eagle Rock Energy G&P, LLC, the general partner of Eagle Rock GP, Vanguard, Talon Merger Sub, and the members of the board of directors of Eagle Rock Energy G&P, LLC (collectively, the “Eagle Rock Defendants”). These lawsuits have been consolidated as Irving and Judith Braun v. Eagle Rock Energy GP, L.P. et al., Case No. 2015-30441, in the District Court of Harris County, Texas, 125th Judicial District (the “Eagle Rock State Lawsuits”). On June 1, 2015, another alleged Eagle Rock unitholder (the “Eagle Rock Federal Plaintiff” and, together with the Eagle Rock State Plaintiffs, the “Eagle Rock Plaintiffs”) filed a class action lawsuit against the Eagle Rock Defendants. This lawsuit is styled Pieter Heydenrych v. Eagle Rock Energy Partners, L.P. et al., Case No. 4:15-cv-01470, in the United States District Court for the Southern District of Texas, Houston Division (the “Eagle Rock Federal Lawsuit” and, together with the Eagle Rock State Lawsuits, the “Eagle Rock Lawsuits”).

The Eagle Rock Plaintiffs allege a variety of causes of action challenging the Eagle Rock merger, including that (i) the members of the board of directors of Eagle Rock G&P, LLC have allegedly breached duties and the implied covenant of good faith and fair dealing in connection with the Eagle Rock merger, and (ii) Eagle Rock GP, Eagle Rock Energy G&P, LLC, Vanguard, and Talon Merger Sub have allegedly aided and abetted in these alleged breaches. The Eagle Rock Federal Plaintiff also alleges that the Eagle Rock Defendants have violated Section 14(a) of the Exchange Act and Rule 14a-9 promulgated thereunder. In general, the Eagle Rock Plaintiffs allege that the Eagle Rock merger (a) provides inadequate consideration to Eagle Rock unitholders, (b) is not subject to minority unitholder approval due to the support agreement and the absence of a majority-of-the-minority vote requirement, (c) contains contractual terms (the no-solicitation, matching rights, and termination fee provisions) that will dissuade other potential merger partners from making alternative proposals, and (d) does not include a collar to protect Eagle Rock unitholders against declines in Vanguard’s unit price. The Eagle Rock Plaintiffs also allege, in general, that the registration statement filed in connection with the Eagle Rock merger fails, among other things, to disclose allegedly material details concerning (i) Eagle Rock’s and Vanguard’s financial and operational projections, (ii) the analysis underlying the opinion of the financial advisor to Eagle Rock, (iii) the analysis underlying the opinion of the financial advisor to Vanguard and (iv) the background of the Eagle Rock merger.

Based on these allegations, the Eagle Rock Plaintiffs seek to enjoin Eagle Rock from proceeding with or consummating the Eagle Rock merger. To the extent that the Eagle Rock merger is consummated before injunctive relief is granted, the Eagle Rock Plaintiffs seek to have the Eagle Rock merger rescinded. The Eagle Rock Federal Plaintiff also seeks damages. The Eagle Rock Plaintiffs also seek attorneys’ fees.

The Eagle Rock Defendants’ date to answer, move to dismiss, or otherwise respond to the Eagle Rock Federal Lawsuit has not yet been set. The Eagle Rock Defendants have answered the Eagle Rock State Lawsuits, denying the allegations therein. Eagle Rock and Vanguard cannot predict the outcome of the Eagle Rock Lawsuits or any others that might be filed subsequent to the date of the filing of this proxy statement/prospectus; nor can Eagle Rock and Vanguard predict the amount of time and expense that will be required to resolve the Eagle Rock Lawsuits. The Eagle Rock Defendants believe the Eagle Rock Lawsuits are without merit and intend to vigorously defend against them.

The completion of the Eagle Rock merger is not a condition to the completion of the merger, and the completion of the merger is not a condition to the completion of the Eagle Rock merger.

TABLE OF CONTENTS

RECENT DEVELOPMENTS

Agreement and Plan of Merger with Eagle Rock

On May 21, 2015, Vanguard and Talon Merger Sub (collectively, the “Vanguard Entities”), entered into the Eagle Rock merger agreement with Eagle Rock and Eagle Rock GP, pursuant to which Vanguard will acquire Eagle Rock in exchange for Vanguard common units, implying an aggregate transaction value of approximately $614 million, including the assumption of Eagle Rock’s existing net debt. The Eagle Rock merger agreement provides that, upon the terms and subject to the conditions set forth in the Eagle Rock merger agreement, Talon Merger Sub will be merged with and into Eagle Rock, with Eagle Rock continuing as the surviving entity and an indirect wholly owned subsidiary of Vanguard.

Under the terms of the Eagle Rock merger agreement, each outstanding Eagle Rock common unit will be converted into the right to receive 0.185 newly issued Vanguard common units or, in the case of fractional Vanguard common units, cash (without interest and rounded up to the nearest whole cent) (the “Eagle Rock merger consideration”). Further, in connection with the Eagle Rock merger agreement, Vanguard will adopt Eagle Rock’s long-term incentive plan and each outstanding award of Eagle Rock common units (including performance units based on Eagle Rock common units, “restricted Eagle Rock units”) issued under such plan will be converted into new awards of Vanguard restricted units. However, any outstanding Eagle Rock restricted units held by employees and officers of Eagle Rock and members of the board of directors of Eagle Rock Energy G&P, LLC, the general partner of Eagle Rock GP, who do not receive offers from Vanguard or who receive “Unqualified Offers” (as such term is defined in the Eagle Rock merger agreement) and do not accept such offers will accelerate upon the effective time of the Eagle Rock merger (as if terminated without cause following a change of control) and be converted into the right to receive the Eagle Rock merger consideration, with the vesting level of performance-based restricted units determined based upon actual performance through the effective time of the Eagle Rock merger (subject to Vanguard’s good faith review). The Eagle Rock Entities and the Vanguard Entities have each made certain representations and warranties and agreed to certain covenants in the Eagle Rock merger agreement. Each of the Eagle Rock Entities and Vanguard has agreed, among other things, subject to certain exceptions, to conduct its respective business in the ordinary course during the period between the execution of the Eagle Rock merger agreement and the effective time of the Eagle Rock merger (unless the Eagle Rock merger agreement is earlier terminated in accordance with its terms). In addition, Eagle Rock has agreed not to solicit alternative business combination transactions during such period, and, subject to certain exceptions, not to engage in discussions or negotiations regarding any alternative business combination transactions during such period.

The closing of the Eagle Rock merger agreement is subject to satisfaction or waiver of customary closing conditions, including, among others, (1) the approval of the Eagle Rock merger agreement by the affirmative vote or consent of the holders of at least a majority of the outstanding Eagle Rock common units, voting as a class, (2) the approval of the issuance of the new Vanguard common units to the Eagle Rock unitholders in connection with the Eagle Rock by the majority of the votes cast affirmatively or negatively by holders of the outstanding Vanguard common units and Vanguard class B units present in person or by proxy at a duly called unitholder meeting, (3) the registration statement on Form S-4 used to register the Vanguard common units to be issued in the Eagle Rock being declared effective by the SEC, (4) the approval for listing of the Vanguard common units issuable as part of the Eagle Rock merger consideration on NASDAQ, (5) subject to specified materiality standards, the accuracy of the representations and warranties of, and the performance of all covenants by, the parties and (6) the delivery of certain tax opinions.

The Eagle Rock merger agreement contains certain termination rights for both Vanguard and Eagle Rock and further provides that, upon termination of the Eagle Rock merger agreement, under certain circumstances, either party may be required to reimburse the other party’s expenses up to $2,317,700 and pay the other party a termination fee equal to $20,000,000.

Prior to entering into the Eagle Rock merger agreement, Vanguard obtained the consent of LRE and the board of directors of LRE GP.

Voting and Support Agreement with Holders of Common Units of Eagle Rock

Simultaneously with the execution of the Eagle Rock merger agreement, Vanguard entered into a Voting and Support Agreement (the “Eagle Rock support agreement”) with each of Montierra Minerals &

TABLE OF CONTENTS

Production, L.P., Montierra Management LLC, Natural Gas Partners VII, L.P., Natural Gas Partners VIII, L.P., NGP Income Management L.L.C., Eagle Rock Holdings NGP 7, LLC, Eagle Rock Holdings NGP 8, LLC, ERH NGP 7 SPV, LLC, ERH NGP 8 SPV, LLC, NGP Income Co-Investment Opportunities Fund II, L.P. and NGP Energy Capital Management, L.L.C. (collectively, the “Eagle Rock Holders” and each, an “Eagle Rock Holder”), and, solely for the waiver of an existing voting agreement and termination and other miscellaneous provisions, Eagle Rock and Eagle Rock GP.

In accordance with the Eagle Rock support agreement, the Eagle Rock Holders have agreed, among other things, to vote all Eagle Rock common units owned by such Eagle Rock Holders in favor of the Eagle Rock merger and the approval of the Eagle Rock merger agreement and against alternative proposals or other proposals made in opposition to approval of the Eagle Rock merger agreement and other actions or transactions which might materially impede or interfere with the Eagle Rock merger or the transactions contemplated by the Eagle Rock merger agreement. The Eagle Rock Holders also agreed to provide Vanguard with an irrevocable proxy over all of their Eagle Rock common units, which will empower Vanguard, subject to the terms of the Eagle Rock support agreement, to vote those units in favor of the Eagle Rock merger agreement and the transactions contemplated thereby on behalf of the Eagle Rock Holders. The foregoing obligations will terminate upon the earliest to occur of (a) the consummation of the Eagle Rock merger or the termination of the Eagle Rock merger agreement in accordance with its terms (the “Eagle Rock expiration date”), (b) the effective date of any waiver, amendment or other modification to the Eagle Rock merger agreement that is materially adverse to the Eagle Rock Holders and (c) a change in recommendation of Eagle Rock regarding the Eagle Rock merger.

The Eagle Rock Holders have also agreed to certain restrictions under the Eagle Rock support agreement, including but not limited to: (i) a restriction on transferring more than 15% of their Eagle Rock common units prior to the Eagle Rock expiration date and (ii) a restriction on soliciting or encouraging alternative proposals. Furthermore, the Eagle Rock Holders agreed to promptly notify Vanguard of any alternative proposal that they receive and to keep Vanguard reasonably informed on the material developments of any such alternative proposals. For a period beginning at the effective time of the Eagle Rock merger and continuing for a period of 90 days thereafter, the Eagle Rock Holders have also agreed not to sell, contract to sell, transfer or otherwise dispose of any Vanguard common units (or any security exercisable or exchangeable for Vanguard common units) received in the transactions contemplated by the Eagle Rock merger agreement, provided that on each trading day during such period, the Eagle Rock Holders may sell, contract to sell, transfer or otherwise dispose of an aggregate number of Vanguard common units (or any security exercisable or exchangeable for Vanguard common units), on a daily basis, not to exceed 10% of the average daily trading volume of Vanguard common units during the four weeks immediately prior to the first day of the calendar month in which such transaction occurs.

Registration Rights Agreement with Holders of Common Units of Eagle Rock

On May 21, 2015, Vanguard entered into a Registration Rights Agreement (the “Eagle Rock registration tights agreement”) with the Eagle Rock Holders. Pursuant to the Eagle Rock registration rights agreement, among other things, (i) no later than the 14th day following the closing date of the Eagle Rock merger, Vanguard will file with the SEC either (a) a registration statement with respect to the public resale of the Vanguard common units received by the Eagle Rock Holders as consideration in the Eagle Rock merger or (b) a post-effective amendment to Vanguard’s existing automatic shelf registration on Form S-3, (ii) the Eagle Rock Holders will have the right to participate in future underwritten public offerings of Vanguard common units and (iii) subject to certain conditions, Vanguard will be obligated to initiate an underwritten offing of the Vanguard common units received by the Eagle Rock Holders as consideration in the Eagle Rock merger.

Third Amended and Restated Credit Agreement

On June 3, 2015, Vanguard entered into the Eighth Amendment to its Third Amended and Restated Credit Agreement (the “Amended Agreement”) which decreased the borrowing base from $2.0 billion to $1.6 billion. The Amended Agreement however provides for an automatic increase in the borrowing base by $200.0 million upon closing of the merger. In addition, the Amended Agreement includes, among other provisions, the amendment of the debt to “Last Twelve Months Adjusted EBITDA” covenant to be greater than 5.5 to 1.0 in 2015, 5.25 to 1.0 in 2016 and 4.5 to 1.0 starting in 2017 and beyond.

TABLE OF CONTENTS

SELECTED HISTORICAL CONSOLIDATED FINANCIAL DATA OF VANGUARD

The following summary historical consolidated data as of and for the years ended December 31, 2014, 2013, 2012, 2011 and 2010 are derived from Vanguard’s audited historical consolidated financial statements. The following selected historical consolidated financial data as of and for the six months ended June 30, 2015 and 2014 are derived from Vanguard’s unaudited condensed consolidated financial statements. In the opinion of Vanguard’s management, all adjustments, consisting of normal recurring adjustments, considered necessary for a fair statement of Vanguard’s financial position at June 30, 2015, and its operating results and cash flows for the six months ended June 30, 2015 and 2014 have been included.

You should read the following historical consolidated financial data in conjunction with Vanguard’s Annual Report on Form 10-K for the year ended December 31, 2014 and its Quarterly Report on Form 10-Q for the quarter ended June 30, 2015, as well as Vanguard’s historical financial statements and notes thereto, which are incorporated by reference into this proxy statement/prospectus. See “Where You Can Find More Information.”

		Six Months Ended June 30,								Year Ended December 31,(4)
		2015				2014				2014				2013				2012(5)				2011(6)				2010
		(in thousands, except per unit data)
Statement of Operations Data:
Revenues:
Oil sales		$	79,801			$	142,163			$	268,685			$	268,922			$	233,153			$	236,003			$	50,022
Natural gas sales			95,651				133,348				285,439				124,513				47,270				47,977				25,778
NGLs sales			19,283				38,748				70,489				49,813				29,933				28,862				9,557
Net gains (losses) on commodity derivative contracts(1)			38,233				(94,436	)			163,452				11,256				36,846				6,735				7,797
Total revenue			232,968				219,823				788,065				454,504				347,202				319,577				93,154
Costs and Expenses:
Production
Lease operating expenses			67,078				64,715				132,515				105,502				74,366				63,944				18,471
Production and other taxes			22,180				31,563				61,874				40,430				29,369				28,621				6,840
Depreciation, depletion, amortization and accretion			130,015				95,118				226,937				167,535				104,542				84,857				22,231
Impairment of oil and natural gas properties			865,975				—				234,434				—				247,722				—				—
Selling, general and administrative expenses(2)			18,193				15,902				30,839				25,942				22,466				19,779				10,134
Total costs and expenses			1,103,441				207,298				686,599				339,409				478,465				197,201				57,676
Income (Loss) from Operations:			(870,473	)			12,525				101,466				115,095				(131,263	)			122,376				35,478
Other Income (Expense):
Interest expense			(40,563	)			(32,808	)			(69,765	)			(61,148	)			(41,891	)			(28,994	)			(5,766	)
Net losses on interest rate derivative contracts			(1,484	)			(1,579	)			(1,933	)			(96	)			(6,992	)			(4,962	)			(2,148	)
Net gain (loss) on acquisitions of oil and natural gas properties			—				32,114				34,523				5,591				11,111				(367	)			(5,680	)
Other income			45				131				54				69				220				77				1
Total other expense			(42,002	)			(2,142	)			(37,121	)			(55,584	)			(37,552	)			(34,246	)			(13,593)

TABLE OF CONTENTS

		Six Months Ended June 30,								Year Ended December 31,(4)
		2015				2014				2014				2013				2012(5)				2011(6)				2010
		(in thousands, except per unit data)
Net Income (Loss)		$	(912,475	)		$	10,383			$	64,345			$	59,511			$	(168,815	)		$	88,130			$	21,885
Less: Net income attributable to non-controlling interest			—				—				—				—				—				(26,067	)			—
Net Income (Loss) Attributable to Vanguard Unitholders		$	(912,475	)		$	10,383			$	64,345			$	59,511			$	(168,815	)		$	62,063			$	21,885
Less: Distributions to Preferred unitholders			(13,380	)			(6,558	)			(18,197	)			(2,634	)			—				—				—
Net Income (Loss) Attributable to Common and Class B unitholders		$	(925,855	)		$	3,825			$	46,148			$	56,877			$	(168,815	)		$	62,063			$	21,885
Net Income (Loss) Per Common and Class B Unit:
Basic		$	(10.86	)		$	0.05			$	0.56			$	0.78			$	(3.11	)		$	1.95			$	1.00
Diluted		$	(10.86	)		$	0.05			$	0.55			$	0.77			$	(3.11	)		$	1.95			$	1.00
Distributions Declared Per Common and Class B Unit(3)		$	0.80			$	1.26			$	2.52			$	2.46			$	2.79			$	2.28			$	2.15
Weighted Average Common Units Outstanding:
Basic			84,816				79,865				81,611				72,644				53,777				31,370				21,500
Diluted			84,816				79,865				82,039				72,992				53,777				31,370				21,500
Weighted Average Class B Units Outstanding			420				420				420				420				420				420				420
Cash Flow Data:
Net cash provided by operating activities		$	164,715			$	154,927			$	339,752			$	260,965			$	204,490			$	176,332			$	71,577
Net cash used in investing activities		$	(57,486	)		$	(573,155	)		$	(1,446,202	)		$	(397,977	)		$	(839,244	)		$	(236,350	)		$	(429,994	)
Net cash provided by (used in) financing activities		$	(103,097	)		$	428,523			$	1,094,632			$	137,267			$	643,466			$	61,041			$	359,758
Other Financial Information:
Adjusted EBITDA attributable to Vanguard unitholders interest		$	175,918			$	187,552			$	421,445			$	309,745			$	230,512			$	164,603			$	80,396

TABLE OF CONTENTS

Non-GAAP Financial Measure

Adjusted EBITDA

Vanguard presents Adjusted EBITDA in addition to its reported net income (loss) attributable to Vanguard unitholders in accordance with GAAP. Adjusted EBITDA is a non-GAAP financial measure that is defined as net income (loss) attributable to Vanguard unitholders plus, for 2011, net income (loss) attributable to the non-controlling interest. The result is net income (loss) which includes the non-controlling interest for 2011. From this Vanguard adds or subtracts the following:

TABLE OF CONTENTS

Adjusted EBITDA is a significant performance metric used by Vanguard management as a tool to measure (prior to the establishment of any cash reserves by the board of directors of Vanguard, debt service and capital expenditures) the cash distributions Vanguard could pay its unitholders. Specifically, this financial measure indicates to investors whether or not Vanguard is generating cash flow at a level that can sustain or support an increase in its monthly distribution rates. Adjusted EBITDA is also used as a quantitative standard by Vanguard’s management and by external users of its financial statements such as investors, research analysts and others to assess the financial performance of Vanguard’s assets without regard to financing methods, capital structure or historical cost basis; the ability of Vanguard’s assets to generate cash sufficient to pay interest costs and support its indebtedness; and Vanguard’s operating performance and return on capital as compared to those of other companies in its industry.

Vanguard’s Adjusted EBITDA should not be considered as an alternative to net income, operating income, cash flow from operating activities or any other measure of financial performance or liquidity presented in accordance with GAAP. Vanguard’s Adjusted EBITDA excludes some, but not all, items that affect net income and operating income and these measures may vary among other companies. Therefore, Vanguard’s Adjusted EBITDA may not be comparable to similarly titled measures of other companies. For example, Vanguard funds premiums paid for derivative contracts, acquisitions of oil and natural gas properties, including the assumption of derivative contracts related to these acquisitions and other capital expenditures primarily with proceeds from debt or equity offerings or with borrowings under Vanguard’s reserve-based credit facility. For the purposes of calculating Adjusted EBITDA, Vanguard consider the cost of premiums paid for derivatives and the fair value of derivative contracts acquired as part of a business combination as investments related to its underlying oil and natural gas properties; therefore, they are not deducted in arriving at Vanguard’s Adjusted EBITDA. Vanguard’s Consolidated Statements of Cash Flows, prepared in accordance with GAAP, present cash settlements on matured derivatives and the initial cash outflows of premiums paid to enter into derivative contracts as operating activities. When Vanguard assumes derivative contracts as part of a business combination, Vanguard allocates a part of the purchase price and assigns them a fair value at the closing date of the acquisition. The fair value of the derivative contracts acquired is recorded as a derivative asset or liability and presented as cash used in investing activities in Vanguard’s Consolidated Statements of Cash Flows. As the volumes associated with these derivative contracts, whether Vanguard entered into them or assumed them, are settled, the fair value is recognized in operating cash flows. Whether these cash settlements on derivatives are received or paid, they are reported as operating cash flows which may increase or decrease the amount Vanguard has available to fund distributions.

As noted above, for purposes of calculating Adjusted EBITDA, Vanguard considers both premiums paid for derivatives and the fair value of derivative contracts acquired as part of a business combination as investing activities. This is similar to the way the initial acquisition or development costs of Vanguard’s oil and natural gas properties are presented in its Consolidated Statements of Cash Flows; the initial cash outflows are presented as cash used in investing activities, while the cash flows generated from these assets are included in operating cash flows. The consideration of premiums paid for derivatives and the fair value of derivative contracts acquired as part of a business combination as investing activities for purposes of determining Vanguard’s Adjusted EBITDA differs from the presentation in its consolidated financial statements prepared in accordance with GAAP which (i) presents premiums paid for derivatives entered into as operating activities and (ii) the fair value of derivative contracts acquired as part of a business combination as investing activities.

TABLE OF CONTENTS

The following table presents a reconciliation of Vanguard’s consolidated net income (loss) to Adjusted EBITDA.

		Six Months Ended June 30,								Year Ended December 31,
		2015				2014				2014				2013				2012				2011(e)				2010(f)
		(in thousands)
Net income (loss) attributable to Vanguard unitholders		$	(912,475	)		$	10,383			$	64,345			$	59,511			$	(168,815	)		$	62,063			$	21,885
Net income attributable to non-controlling interest			—				—				—				—				—				26,067				—
Net income (loss)			(912,475	)			10,383				64,345				59,511				(168,815	)			88,130				21,885
Plus:
Interest expense			40,563				32,808				69,765				61,148				41,891				28,994				5,766
Depreciation, depletion, amortization and accretion			130,015				95,118				226,937				167,535				104,542				84,857				22,231
Impairment of oil and natural gas properties			865,975				—				234,434				—				247,722				—				—
Net (gains) losses on commodity derivative contracts			(38,233	)			94,436				(163,452	)			(11,256	)			(36,846	)			(6,735	)			(7,797	)
Net cash settlements received (paid) on matured commodity derivative(a)(b)(c)			80,620				(19,380	)			10,187				30,905				39,102				18,720				25,887
Net losses on interest rate derivative contracts(d)			1,484				1,579				1,933				96				6,992				4,962				2,148
Net (gain) loss on acquisitions of oil and natural gas properties			—				(32,114	)			(34,523	)			(5,591	)			(11,111	)			367				5,680
Texas margin taxes			142				(281	)			(630	)			601				239				261				(12	)
Compensation related items			7,827				5,003				11,710				5,931				6,796				3,026				1,026
Transaction costs incurred on acquisitions and mergers			—				—				739				865				—				2,019				3,583
Less:
Interest income			—				—				—				—				—				—				(1	)
Adjusted EBITDA before non-controlling interest		$	175,918			$	187,552			$	421,445			$	309,745			$	230,512			$	224,601			$	80,396
Non-controlling interest attributable to adjustments above			—				—				—				—				—				(62,838	)			—
Administrative services fees eliminated in consolidation			—				—				—				—				—				2,840				—
Adjusted EBITDA attributable to Vanguard unitholders		$	175,918			$	187,552			$	421,445			$	309,745			$	230,512			$	164,603			$	80,396

TABLE OF CONTENTS

(a) Excludes premiums paid, whether at inception or deferred, for derivative contracts that settled during the period. Vanguard considers the cost of premiums paid for derivatives as an investment related to Vanguard’s underlying oil and natural gas properties		$	2,567			$	—			$	—			$	220			$	11,641			$	11,346			$	1,950
(b) Excludes the fair value of derivative contracts acquired as part of prior period business combinations that apply to contracts settled during the period. Vanguard considers the amounts paid to sellers for derivative contracts assumed with business combinations a part of the purchase price of the underlying oil and natural gas properties		$	20,281			$	10,864			$	21,306			$	30,200			$	26,505			$	169			$	1,995
(c) Excludes fair value of restructured derivative contracts		$	(31,945	)		$	—			$	—			$	—			$	—			$	—			$	—
(d) Includes settlements paid on interest rate derivatives		$	1,980			$	2,005			$	4,035			$	3,888			$	2,515			$	2,874			$	1,799
(e) Results of operations from oil and natural gas properties acquired in the ENP Purchase through the date of the completion of the ENP Merger on December 1, 2011 were subject to a 53.4% non-controlling interest.
(f) As the ENP Purchase was completed on December 31, 2010, no results of operations were included for the year ended December 31, 2010.

TABLE OF CONTENTS

SELECTED HISTORICAL CONSOLIDATED FINANCIAL DATA OF LRE

The following summary historical consolidated data as of and for the years ended December 31, 2014, 2013 and 2012 and for the period from November 16, 2011 to December 31, 2011 are derived from LRE’s audited historical consolidated financial statements. The selected financial data for the period from January 1, 2011 to November 15, 2011 and as of and for the year ended December 31, 2010 are derived from the audited financial statements of LRE’s predecessor. References to “LRE’s predecessor” refer collectively to LRR A, LRR B and LRR C, which sold and contributed oil and natural gas properties and related net profits interests and operations to LRE in connection with LRE’s initial public offering. The following selected historical consolidated financial data as of and for the six months ended June 30, 2015 and 2014 are derived from LRE’s unaudited condensed consolidated financial statements. In the opinion of LRE’s management, all adjustments, consisting of normal recurring adjustments, considered necessary for a fair statement of LRE’s financial position at June 30, 2015, and its operating results and cash flows for the six months ended June 30, 2015 and 2014 have been included.

You should read the following historical consolidated financial data in conjunction with LRE’s Annual Report on Form 10-K for the year ended December 31, 2014 and its Quarterly Report on Form 10-Q for the quarter ended June 30, 2015, as well as LRE’s historical financial statements and notes thereto, which are incorporated by reference into this proxy statement/prospectus. See “Where You Can Find More Information.”

(in thousands, except per unit data)		LRE																								Predecessor
		Six Months Ended June 30, 2015				Six Months Ended June 30, 2014				Year Ended December 31, 2014				Year Ended December 31, 2013				Year Ended December 31, 2012				November 16 to December 31, 2011				January 1 to November 15, 2011				Year Ended December 31, 2010
Statement of Operations Data:
Revenues:
Oil sales		$	26,291			$	40,510			$	76,662			$	77,181			$	72,916			$	9,766			$	59,605			$	52,670
Natural gas sales			7,986				15,664				28,521				26,800				23,502				3,976				35,883				48,088
Natural gas liquids sales			2,832				6,124				11,362				10,147				11,627				1,976				14,500				14,748
Gain (loss) on commodity derivative instruments, net			9,755				(18,950	)			71,235				781				12,748				12,287				22,027				24,065
Other income			55				71				125				186				45				—				159				116
Total revenues			46,919				43,419				187,905				115,095				120,838				28,005				132,174				139,687
Operating expenses:
Lease operating expenses			12,780				12,664				25,821				25,397				29,069				3,193				21,391				23,804
Production and ad valorem taxes			2,748				4,648				8,738				8,614				7,790				1,076				7,763				9,320
Depletion and depreciation			17,574				17,145				36,729				43,420				46,928				5,876				37,206				55,828
Impairment of oil and gas properties			35,962				—				37,758				63,663				3,544				—				16,765				11,712
Accretion expense			1,029				1,013				2,071				1,924				1,575				191				1,290				1,366
Loss (gain) on settlement of asset retirement obligations			68				61				151				358				(31	)			—				496				(209	)
Management fees			—				—				—				—				—				—				5,435				6,104
General and administrative expenses			16,464				5,881				11,447				11,965				13,758				1,892				5,149				5,293
Total operating expenses			86,625				41,412				122,715				155,341				102,633				12,228				95,495				113,218
Operating income (loss)			(39,706	)			2,007				65,190				(40,246	)			18,205				15,777				36,679				26,469

TABLE OF CONTENTS

(in thousands, except per unit data)		LRE																								Predecessor
		Six Months Ended June 30, 2015				Six Months Ended June 30, 2014				Year Ended December 31, 2014				Year Ended December 31, 2013				Year Ended December 31, 2012				November 16 to December 31, 2011				January 1 to November 15, 2011				Year Ended December 31, 2010
Other income (expense), net:
Interest income		$	—			$	—			$	—			$	—			$	—			$	—			$	1			$	17
Interest expense			(5,889	)			(5,116	)			(10,472	)			(9,235	)			(6,596	)			(604	)			(919	)			(3,223	)
Gain (loss) on interest rate derivative instruments, net			(1,673	)			(1,422	)			(1,790	)			1,256				(4,650	)			—				(133	)			(897	)
Other income (expense), net			(7,562	)			(6,538	)			(12,262	)			(7,979	)			(11,246	)			(604	)			(1,051	)			(4,103	)
Income (loss) before taxes			(47,268	)			(4,531	)			52,928				(48,225	)			6,959				15,173				35,628				22,366
Income tax (expense) benefit			18				(112	)			(186	)			(56	)			(172	)			(48	)			76				(32	)
Net income (loss)		$	(47,250	)		$	4,643			$	52,742			$	(48,281	)		$	6,787			$	15,125			$	35,704			$	22,334
Net (income) loss attributable to common control operations			—				—				—				(448	)			(6,790	)			(2,975	)			—				—
Net income (loss) available to unitholders		$	(47,250	)		$	(4,643	)		$	52,742			$	(48,729	)		$	(3	)		$	12,150				—				—
General partner’s interest in net income (loss)		$	(9,434	)		$	(4	)		$	53			$	(49	)		$	—			$	12				—				—
Limited partners’ interest in net income (loss)		$	(37,816	)		$	(4,639	)		$	52,689			$	(48,680	)		$	(3	)		$	12,138				—				—
Net income (loss) per limited partner unit (basic and diluted)		$	(1.35	)		$	(0.17	)		$	1.94			$	(1.92	)		$	(0.00	)		$	0.54				—				—
Weighted average number of limited partner units outstanding (basic and diluted)			28,073				26,539				27,092				25,372				22,425				22,418				—				—
Other Financial Data:
Adjusted EBITDA		$	40,169			$	40,677			$	88,385			$	79,550			$	81,156			$	13,603			$	79,762			$	119,130
Cash Flow Data:
Net cash provided by (used in) operating activities		$	35,954			$	31,663			$	67,885			$	65,541			$	77,223			$	5,523			$	84,027			$	121,269
Net cash provided by (used in) investing activities		$	(17,606	)		$	(17,029	)		$	(69,950	)		$	(35,805	)		$	(40,433	)		$	(755	)		$	(44,981	)		$	(125,846	)
Net cash provided by (used in) financing activities		$	(14,243	)		$	(16,180	)		$	1,224			$	(28,786	)		$	(34,836	)		$	(3,255	)		$	(38,000	)		$	1,505

TABLE OF CONTENTS

Non-GAAP Financial Measures

LRE discloses the non-GAAP financial measures Adjusted EBITDA and Distributable Cash Flow for the periods presented and provides reconciliations of these items to net income (loss), LRE’s most directly comparable financial performance measure calculated and presented in accordance with GAAP. LRE defines Adjusted EBITDA as net income (loss) plus or minus:

Adjusted EBITDA is used as a supplemental financial measure by LRE’s management and by external users of LRE’s financial statements, such as investors, commercial banks, research analysts and others, to assess LRE’s financial performance as compared to that of other companies and partnerships in its industry, without regard to financing methods, capital structure or historical cost basis.

LRE defines Distributable Cash Flow as Adjusted EBITDA less cash income tax expense, cash interest expense and estimated maintenance capital.

Distributable Cash Flow is a supplemental financial measure used by LRE’s management and by external users of LRE’s financial statements, such as investors, commercial banks, research analysts and others to compare basic cash flows generated by LRE (prior to the establishment of any retained cash reserve by LRE GP) to the cash distributions LRE expects to pay its unitholders. Distributable Cash Flow is also an important financial measure for LRE’s unitholders as it serves as an indicator of its success in providing a cash return on investment. Specifically, distributable cash flow indicates to investors whether or not LRE is generating cash flow at a level that can sustain or support an increase in its quarterly distribution rates. Distributable Cash Flow is a quantitative standard used throughout the investment community with respect to publicly-traded partnerships and limited liability companies because the yield is based on the amount of cash distributions the entity pays to a unitholder compared to the unit price.

LRE’s management believes that both Adjusted EBITDA and Distributable Cash Flow are useful to investors because these measures are used by many partnerships in the industry as measures of operating and financial performance and are commonly employed by financial analysts and others to evaluate the operating and financial performance from period to period and to compare it with the performance of other publicly traded partnerships within the industry. Adjusted EBITDA and Distributable Cash Flow should not be considered alternatives to net income (loss), operating income (loss), or any other measures of financial performance presented in accordance with GAAP. LRE’s Adjusted EBITDA and Distributable Cash Flow may not be comparable to similarly titled measures of another company because all companies may not calculate Adjusted EBITDA and Distributable Cash Flow in the same manner.

LRE’s Adjusted EBITDA for the six months ended June 30, 2015 and 2014, for the years ended December 31, 2014, 2013, 2012, and for the period from November 16 to December 31, 2011 was $40.2 million, $40.7 million, $83.4 million, $79.6 million, $81.2 million, and $13.6 million, respectively. LRE’s predecessor’s Adjusted EBITDA for the period from January 1 to November 15, 2011 and the year ended December 31, 2010 was $79.8 million and $119.1 million, respectively.

TABLE OF CONTENTS

LRE’s Distributable Cash Flow for the six months ended June 30, 2015 and 2014, for the years ended December 31, 2014, 2013, and 2012 and for the period from November 16 to December 31, 2011 was $23.9 million, $25.2 million, $52.0 million, $49.6 million, $53.8 million and $11.0 million, respectively.

The following table presents a reconciliation of Adjusted EBITDA and Distributable Cash Flow to net income (loss), LRE’s most directly comparable GAAP financial performance measure, for each of the periods indicated.

(in thousands)		LRE																								Predecessor
		Six Months Ended June 30, 2015				Six Months Ended June 30, 2014				Year Ended December 31, 2014				Year Ended December 31, 2013				Year Ended December 31, 2012				November 16 to December 31, 2011				January 1 to November 15, 2011				Year Ended December 31, 2010
Net income (loss)		$	(47,250	)		$	(4,643	)		$	52,742			$	(48,281	)		$	6,787			$	15,125			$	35,704			$	22,334
Income tax expense (benefit)			(18	)			112				186				56				172				48				(76	)			32
Interest expense – net, including loss (gain) on interest rate derivative instruments, net			7,562				6,538				12,262				7,979				11,246				604				1,052				4,120
Depletion and depreciation			17,574				17,145				36,729				43,420				46,928				5,876				37,206				55,828
Accretion of asset retirement obligations			1,029				1,013				2,071				1,924				1,575				191				1,290				1,366
Amortization of equity awards			838				534				1,081				549				313				31				—				—
Loss (gain) on settlement of asset retirement obligations			68				61				151				358				(31	)			—				496				(209	)
Loss (gain) on commodity derivative instruments, net			(9,755	)			18,950				(71,235	)			(781	)			(12,748	)			(12,287	)			(22,027	)			(24,065	)
Commodity derivative instrument net cash settlements			25,061				967				11,640				10,663				23,370				4,015				9,353				48,029
Impairment of oil and natural gas properties			35,962				—				37,758				63,663				3,544				—				16,765				11,712
Other non-recurring items			9,098				—				—				—				—				—				—				—
Interest income			—				—				—				—				—				—				(1	)			(17	)
Adjusted EBITDA		$	40,169			$	40,677			$	83,385			$	79,550			$	81,156			$	13,603			$	79,762			$	119,130
Adjusted EBITDA		$	40,169			$	40,677			$	83,385			$	79,550			$	81,156			$	13,603
Cash income tax expense			(85	)			(88	)			(146	)			(132	)			(86	)			—
Cash interest expense			(6,638	)			(5,401	)			(10,905	)			(9,513	)			(7,012	)			(31	)
Estimated maintenance capital(1)			(9,500	)			(10,000	)			(20,300	)			(20,300	)			(20,300	)			(2,538	)
Distributable cash flow		$	23,946			$	25,188			$	52,034			$	49,605			$	53,758			$	11,034

TABLE OF CONTENTS

SELECTED UNAUDITED PRO FORMA COMBINED FINANCIAL INFORMATION

The following selected unaudited pro forma combined balance sheet as of June 30, 2015 reflects the transactions contemplated by the merger agreement and the transactions contemplated by the Eagle Rock merger agreement as if they occurred on June 30, 2015. The unaudited pro forma combined statements of operations for the year ended December 31, 2014 and the six months ended June 30, 2015 reflect the transactions contemplated by the merger agreement, the transactions contemplated by the Eagle Rock merger agreement and certain acquisitions made by Vanguard in 2014 as if they occurred on January 1, 2014.

The following selected unaudited pro forma combined financial information has been prepared for illustrative purposes only and is not necessarily indicative of what the combined organization’s financial position or results of operations actually would have been had the transactions contemplated by the merger agreement and the transactions contemplated by the Eagle Rock merger agreement been completed as of the dates indicated. In addition, the unaudited pro forma combined financial information does not purport to project the future financial position or operating results of the combined organization. Future results may vary significantly from the results reflected because of various factors. The following selected unaudited pro forma combined financial information should be read in conjunction with the section entitled “Unaudited Pro Forma Combined Financial Information” and related notes included in this proxy statement/prospectus.

The completion of the Eagle Rock merger is not a condition to the completion of the merger and there can be no assurance that the transactions contemplated by the Eagle Rock merger agreement will be completed.

Unaudited Pro Forma Combined Balance Sheet Data as of June 30, 2015

		Historical								Pro Forma Adjustments				Vanguard/ LRE Pro Forma Combined				Historical				Pro Forma Adjustments				Vanguard/ LRE/Eagle Rock Pro Forma Combined
(in thousands)		Vanguard				LRE												Eagle Rock
Total assets		$	2,768,042			$	502,863			$	(17,531	)		$	3,253,374			$	562,178			$	7,313			$	3,822,865
Total liabilities		$	2,190,403			$	349,881			$	(4,189	)		$	2,536,095			$	276,970			$	30,449			$	2,843,514
Total members’ equity		$	577,639			$	152,982			$	(13,342	)		$	717,279			$	285,208			$	(23,136	)		$	979,351
Total liabilities and members’ equity		$	2,768,042			$	502,863			$	(17,531	)		$	3,253,374			$	562,178			$	7,313			$	3,822,865

Unaudited Pro Forma Combined Statement of Operations Data for the Year Ended December 31, 2014

(in thousands except per unit data)		Vanguard As Adjusted(1)				LRE Historical				Pro Forma Adjustments				Vanguard/ LRE Pro Forma Combined				Eagle Rock Historical				Pro Forma Adjustments				Vanguard/ LRE/Eagle Rock Pro Forma Combined
Total revenues		$	902,083			$	187,905			$	(4	)		$	1,089,984			$	298,204			$	—			$	1,388,188
Total costs and expenses			710,724				122,715				(16,198	)			817,241				585,259				(41,353	)			1,361,147
Income from operations			191,359				65,190				16,194				272,743				(287,055	)			41,353				27,041
Income (loss) from continuing operations attributable to common and Class B unitholders		$	95,125			$	52,742			$	20,643			$	168,510			$	(352,367	)		$	45,670			$	(138,187)

TABLE OF CONTENTS

(in thousands except per unit data)		Vanguard As Adjusted(1)				LRE Historical				Pro Forma Adjustments				Vanguard/ LRE Pro Forma Combined				Eagle Rock Historical				Pro Forma Adjustments				Vanguard/ LRE/Eagle Rock Pro Forma Combined
Income (loss) from continuing operations per common and Class B Unit
Basic		$	1.16			$	1.94				—			$	1.73			$	(2.25	)			—			$	(1.09	)
Diluted		$	1.14			$	1.94				—			$	1.71			$	(2.25	)			—			$	(1.09	)

(in thousands except per unit data)		Vanguard Historical				Pinedale Acquisition Adjustments				Piceance Acquisition Adjustments				Vanguard As Adjusted
Total revenues		$	788,065			$	14,259			$	99,759			$	902,083
Total costs and expenses			686,599				5,785				18,340				710,724
Income from operations			101,466				8,474				81,419				191,359
Net income (loss) attributable to common and Class B unitholders		$	46,148			$	(24,628	)		$	73,605			$	95,125
Net income per common and Class B Unit
Basic		$	0.56				—				—			$	1.16
Diluted		$	0.55				—				—			$	1.14