Effects of saccharomyces cerevisiae supplementation on milk production, insulin sensitivity and immune response in transition dairy cows during hot season

Abstract The objectives were to determine effects of feeding a live yeast supplement on the productive performance, blood metabolic profile, the immune function, and insulin sensitivity traits of transition dairy cows under the hot months of summer. From 21 d before expected date of calving until d 60 postpartum, two groups of multiparous Holstein cows (6 cows per treatment) were fed a diet without or with live yeast supplement (4 g yeast/d/head). Blood was collected on d −14, 0, 14, 28, and 60 d relative to parturition and analyzed for nonesterified fatty acids, β-hydroxybutyrate, glutamic pyruvic transaminase, glutamic oxaloacetic transaminase, creatinine, urea-N, triiodothyronine, and thyroxine. Plasma concentrations of histamine and heat shock protein 70 (Hsp70) were also determined on d –21, 14, 28, and 49 relative to parturition. An intravenous glucose challenge was made on d 14 postpartum. The cell-mediated immune and humoral responses were established through phytohemagglutinin challenge and ovalbumin immunization, respectively. Prepartum DM intake was greater in yeast-fed cows; however, this difference disappeared after parturition. Cows receiving yeast supplement produced more milk (+1.40 kg/d) and had greater concentrations of milk fat and total solid than those receiving no yeast. Loss of body condition score from calving to d 21 postpartum tended to be lower in yeast-fed cows than control cows. Yeast supplementation had no effect on the response variables to the glucose tolerance test. Plasma concentration of Hsp70 was also lower on d 14 and 28 after parturition in yeast-fed cows. Yeast supplementation enhanced cellular immune function; however, it had no effect on immunoglobulin G secretion against ovalbumin immunization. Overall, live yeast supplementation benefited milk production and milk composition, lowered plasma level of Hsp70, and enhanced the lymphocyte proliferative response in transition dairy cows, which may suggest an immunomodulatory effect of yeast supplement.