Effect of stoned olive oil cake on rumen bacterial community: preliminary results o fan in vitro study

Understanding the effect of diet on the biohydrogenation (BH) process is important to optimize the production of healthful food from ruminant livestock. From literature, it is well known that the availability of C18:1 trans11 (vaccenic acid, VA) and C18:2 cis9 trans11 (rumenic acid) in ruminant products is limited as consequence of their hydrogenation to C18:0 (stearic acid) by rumen microbial activity. Rumen fermentation can be modulated by presence in feeds of bioactive molecules that are able to affect the structure and diversity of rumen microbial populations. In an in vitro trial the effect of stoned virgin olive cake (SVOC), rich in polyphenols, that are potentially able to interfere with rumen fermentation involved in BH processes and methane production, has been investigated. The inclusion of SVOC in feeds at the level of 50 g/kg and 90 g/kg induced changes in fatty acid profile and in microbial populations; in particular, the contemporary disappear of a band (DGGE) related to Butyrivibrio proteoclasticus and the accumulation of VA (+50%) has been observed. Moreover, a depression of other microbial groups mainly related to the orders Clostridiales and Neisseriales has been detected.