Evaluating the effects of direct-fed microbial supplementation on the performance, milk quality and fatty acid of mid-lactating dairy cows.

Abstract

The objective of the experiment was to investigate the effect of a mixture of direct-fed microbial (DFM) on feed intake, nutrient digestibility, milk yield and composition, milk fatty acid and blood parameter in crossbred mid-lactating cows. Twenty-four crossbred Holstein cows (body weight = 650±15kg; days in milk = 100±20; daily milk yield = 25±3kg) were used in a completely randomized design with three treatments: (1) CON, without DFM; (2) LS, inoculation with Lactobacillus fermentum (4.5 × 108 CFU/day) plus Saccharomyces cerevisiae (1.4×1010 CFU/day); and (3) LSM, inoculation with LS plus Megasphaera elsdenii (4.5 × 108 CFU/day). All animals received the same ration with 45.7% forage and 54.3% concentrate. Results showed that the highest feed intake was observed in treatments LS and LSM (p = 0.02). Compared with the CON, milk production, 4% fat-corrected milk, energy-corrected milk, fat (kg/day), protein (kg/day) and lactose (kg/day), FE and percent of fat were increased (p<0.05) by LSM, but unaffected by LS. Also, compared with the CON, both LS and LSM increased antioxidant activity (p<0.05). The concentration of C18:2c n-6 increased significantly in treatment LSM compared with the CON (p = 0.003). The concentration of C20:0 increased significantly in treatment LS compared with the CON (p = 0.004). The highest concentrations of insulin, glucose, triglyceride and cholesterol were observed by LSM (p<0.05). Compared with the CON, both LS and LSM increased blood monocyte, neutrophil, eosinophil and basophil (p<0.05), and blood lymphocyte was increased (p = 0.02) only by LSM. The results of the research showed that the use of DFMs had no effect on the digestibility, microbial load and the major part of fatty acids in milk. However, it improved feed intake, milk yield and antioxidant activity of milk and also increased the milk concentration of C18:2 n-6.