Effect of unsaturated C18 fatty acids (oleic, linoleic and α-linolenic acids) on ruminal fermentation and production of fatty acids isomers in artificial rumen

摘要

The objective of this study was to examine the effect of oleic (OA), linoleic (LA) and |á-linolenic (ALA) acid used as supplements (3.5% wt/wt) to a diet containing 80% lucerne and 20% barley on rumen fermentation and lipid metabolism in an artificial rumen (Rusitec). The experiment lasted 12 days with 6 days of stabilization period. The fatty acid (FA) supplementation to a mixed diet did not affect any parameters of rumen fermenta- tion (degradation of DM, NDF, ADF, total VFA production, production of acetate, propionate and butyrate). The methane production was decreased numerically (NS) by FA supplements (OA, LA, and ALA by about 8, 8.3 and 13.2%, respectively). The stoichiometric parameters of rumen fermentation such as N (nitrogen incorporated by M microflora), OMF (organic matter fermented) and EMS (efficiency of microbial protein synthesis) were affected by unsaturated C FA to a different extent. EMS calculated from N and OMF was significantly (P C ) increased and proportion of 18:0 MCFA (medium chain fatty acids, C ¨C ) decreased after OA, LA and ALA addition. The biohydrogenation 14:0 17:0 (BH) of fatty acids was characterized by increased (NS) accumulation of stearic acid and trans isomers C and 18:1 lower SFA/UFA ratio in the effluent. The concentrations of two main BH intermediates, TVA (trans 11 C ) and 18:1 CLA (cis 9, trans 11 C ), significantly (P < 0.001) increased (TVA ¨C 1.06, 1.29 and 1.10; CLA ¨C 0.32, 0.43 an 18:2 0.36 mg/g rumen fluid DM, respectively) after OA, LA and ALA supplementation compared to the control (TVA ¨C 0.7; CLA ¨C 0.23