Effect of Saccharomyces cerevisiae byproducts on milk phagocyte function and milk production in mid-lactation cows

Saccharomyces cerevisiae is a supplement option for ruminants due to its ability to stimulate the immune system and productivity; however, there are few studies that demonstrate the effectiveness of this yeast in dairy cattle, especially regarding its effect on milk phagocyte function. Thus, this study examined the effect of two presentations of autolyzed S. cerevisiae on milk phagocyte function and milk production in healthy Holstein cows from the third to the fifth months of lactation with somatic cell count (SCC) less than 200,000 cells mL(-1). Ten animals received cell wall-rich S. cerevisiae autolysate (WC 15 g animal day(-1)); 8 received the cytoplasm-rich extract (CYT 5 g animal day(-1)) and 7 received a diet without supplementation (C, control) for 60 days. Weekly oxidative metabolism analysis of milk leukocytes, production and milk constituents was carried out. The oxidative metabolism of milk leukocytes was higher in the WC group than in the C group between D32 and D48 (P <= 0.05) and in the CYT group than in the C group between D24 and D40 (P <= 0.05). The production and percentage of milk fat increased in CYT at D48 and D56. It is concluded that the CYT group had a greater effect on productivity, while on immunity the effect was intermediate, compared to the WC group, which was efficient in improving the immunity of the mammary gland.