Trans11 to trans10 shift of ruminal biohydrogenation of fatty acids and changes in rumen microbiota

Ruminal microbiota plays an important role in ruminant health and productivity. Ruminal metabolism of dietary fatty acids (FA) biohydrogenates polyunsaturated FA (PUFA) to saturated FA via intermediates which usually have a trans11 (t11) double-bond. High-starch and high-oil diets are known to result in a shift of the biohydrogenation (BH) pathway from t11 to trans10 (t10) isomers, and t10 FA are known to decrease milk fat content and to possibly harm human consumers’ health. The present study, using high-throughput 16S rRNA-based pyrosequencing, aimed to provide a comprehensive examination of the bacterial community found in the rumen contents of cows fed four different diets (two levels of starch combined with two levels of unsaturated fat), leading to a wide ranges in the proportions of t10 and t11. Barcoded reads (440 bp) of the V3-V4 regions of the 16S rRNA genes, were obtained from a 454 GS-FLX sequencer