* Q3 underlying sales growth seen up 5.6 pct - Rtrs pollBy Dominique VidalonPARIS, Oct 18 (Reuters) - Consumption trends for the rest of the year and in 2012 amid global recession fears will be in focus along with the outlook for commodity prices when French food group Danone reports third quarter sales on Tuesday.The world’s largest yoghurt maker is expected to post higher sales but slower growth in the third quarter as challenges in the Russian and U.S. dairy markets and a return to more normal growth rates at its water business take their toll, and investors will be keen to hear whether the weakness is temporary.”Investors are also likely to watch for any initial guidance on 2012 input cost inflation, which should be more benign than 2011” Societe Generale analysts said in a note.Analysts polled by Reuters on average expect Danone to post third-quarter sales of 4.8 billion euros, a reported rise of 10.6 percent. Closely-watched underlying sales growth is forecast at 5.6 percent.This would mark a slowdown from 8.7 percent in the first half. Danone Chief Executive Franck Riboud said last month he expected underlying growth of 5-6 percent in the quarter.Danone, whose brands include Actimel and Activia, at the time kept its targets for full-year underlying sales growth of 6-8 percent and for an improvement in operating margin of 20 basis points.Danone has forecast a rise of 6-9 percent in commodity costs this year and it raised its prices during the first half to combat this expected rise.Attention will also focus on the newly acquired Russian Unimilk business, which has suffered from higher milk costs and a repositioning of the business towards higher value-added milk products, which comes at the expense of sales volumes.Russia accounts for 11 percent of Danone’s sales, as does France, and they are the two top contributors to group sales.Meanwhile, the U.S. market, where Danone generates 8 percent of sales, has been seeing strong growth in the Greek yoghurt segment, which has cannibalised other areas where Danone has a stronger presence, analysts said. To address that situation, Danone relaunched a Greek yoghurt in July in the United States.Danone’s water business was boosted in the second quarter by strong demand from Japan after the Fukushima nuclear disaster and by warm weather in Europe. Third-quarter water sales are expected to reflect poorer weather in Western Europe.Danone’s acquisition strategy will also be in focus after it said it was on the lookout for expansion in fast-growing markets.