Effects of enzymatically hydrolyzed yeast supplementation on blood attributes, antioxidant status and gene expression of cytokines in vaccinated dairy cows

This study was done to assess the effects of hydrolyzed yeast on blood cells counts, antioxidant status and gene expression of pro-inflammatory and anti-inflammatory cytokines of vaccinated dairy cows. Twenty Holstein lactating dairy cows were randomly divided into four groups received basal diet without (control) and with 10, 20 and 30 g/d/head of hydrolyzed yeast. Cows were vaccinated against foot and mouth disease virus at day 10 and blood samples were taken 10 days after. Cows received hydrolyzed yeast at doses of 20 and 30 g/d/head had the lowest and those in the control group had the highest malondialdehyde concentration. Cows received hydrolyzed yeast at dose of 20 g/d/head had the highest lymphocyte and the lowest neutrophil/lymphocyte ratio. IL-1 beta and TNF-alpha downregulated and INF-gamma up-regulated in cows received different doses of hydrolyzed yeast. The lowest expression of IL-1 beta and TNF-alpha and the highest expression of INF-gamma was for cows received hydrolyzed yeast at dose of 20 g/d/head. The highest titers against foot and mouth disease virus were for cows received hydrolyzed yeast at dose of 20 g/d/head and the lowest titer was for the control group. Supplementation of 20 g/d/head hydrolyzed yeast recommended in vaccinated cows.