Rumen biohydrogenation and milk fatty acid profile in dairy ewes divergent for feed efficiency

A sustainable increase in livestock production would require selection for improved feed efficiency, but the mechanisms underlying this trait and explaining its large individual variation dairy ruminants remain unclear. This study was conducted lactating ewes to test hypothesis that rumen biohydrogenation (BH) differ between high- low-efficiency animals, these differences be reflected fatty acid (FA) profile affect milk FA composition. second aim identify may serve as biomarkers of efficiency. Data daily intake yield composition, well body weight, were collected individually over a 3-wk period 40 ewes. The difference mean actual predicted (estimated through metabolizable energy requirements maintenance, production, weight change) used efficiency index (FEI) select 8 highest (H-FE) lowest (L-FE) animals. In addition, residual (RFI) estimated term from regression on various sinks. Rumen composition characterized by using gas chromatography, results analyzed statistical model included fixed effect group (H-FE vs. L-FE). FEI averaged ?0.29 ± 0.046 0.81 0.084 H-FE L-FE, respectively, whereas RFI ?0.16 0.18 0.082, respectively. correlation coefficient both metrics 0.69. Feed similar groups, showed greater yield, with increases lactose content protein fat production. Results profiles lower proportion 18:2n-6, cis-9 18:1, several their BH metabolites, concentration 18:0, which indicate apparent more complete efficient sheep. Milk analysis suggested mostly explained increased de novo synthesis, have proportions 18:1 C20 22n-6 polyunsaturated than L-FE. Stepwise multiple linear PUFA might convenient discriminate Further research is needed validate findings (e.g., under different dietary conditions).