UPDATE 1-Global dairy prices fall, after six auctions of gains

(Adds analyst comment, market reaction) By Charlotte Greenfield WELLINGTON, June 21 (Reuters) - Global dairy prices slipped, breaking a winning streak of six consecutive rises, at a fortnightly auction on Wednesday, as whole milk powder softened. The Global Dairy Trade (GDT) Price Index dipped 0.8 percent, with an average selling price of $3,434 per tonne, in the auction held in the early hours of Wednesday morning. The index had risen 0.6 pct at the previous sale. After two yea