Effects of acetate and long-chain fatty acids infusion into external pudic artery on lactation performance and milk fatty acid composition in lactating dairy cows

Abstract

Our objective was to observe the effects of milk fat substrates (MFS) [acetate combined with long-chain fatty acid (FA)] supplementation on lactation performance and milk FA composition of cows fed an energy-and nutrient-deficient diet. Eight Holstein cows (99 ± 11 d) were averagely assigned to two diets based on either corn stover (CS) or mixed forages (MFs). Experiment included two stages and each lasted for 27 d with a 21 d preliminary and a 6 d infusion. Cows with CS diet [NE L = 1.35 Mcal kg −1 of dry matter (DM)] received carrier at the first 3 d and MFS at the following 3 d of infusion period. Cows with MF diet (NE L = 1.66 Mcal kg −1 of DM) received carrier during the 6 d infusion period. The differences in milk production, milk yields of fat, and protein between the two diet groups were compensated by MFS infusion (from −3.5 to −1.3, −0.19 to −0.08, and −0.13 to −0.07 kg d −1 , respectively). Infusion of MFS increased the concentrations of 18:2 and 18:3 in milk fat. The results suggested that supplement of MFS could influence milk fat synthesis and lactation performance in cows fed an energy-and nutrient-deficient diet.