Changes in immune system and intestinal bacteria of cows during the transition period

High-yield dairy cows need high energy feed during periods of increased milk production. The transitional feeding to high energy feed increases the risk of developing a variety of metabolic disorders. Here, five Holstein cows were fed a four-stage feeding protocol (3 weeks for each stage) ranging from 54.9 to 73.7% total digestive nutrients (TDN). The purpose of the study was to investigate the effect of lactic acid bacteria on high-energy-fed cows associated with transitional feeding, and to evaluate the effects of probiotics on intestinal bacterial changes and inflammatory responses. Three feed transition periods were established for five cows, and Lactobacillus plantarum RGU-LP1 (LP1) was fed as a probiotic during the high-energy feeding period. The number of lymphocyte subsets such as CD3-, CD4-, and CD8 positive cells decreased in response to the high energy feed. Lipopolysaccharide (LPS)-induced cytokine (IL-1β and IL-2) gene expression in peripheral blood mononuclear cells (PBMCs) was shown to increase in those animals receiving the high energy feed. However, supplementation with LP1 resulted in an increase in the number of lymphocyte subsets and the expression of IL-1β and IL-2 were returned to the level at low energy diet. These results suggest that high energy diets induce inflammatory cytokine responses following LPS stimulation, and that the addition of LP1 mitigates these results by regulating the LPS-induced inflammatory reaction. Therefore, the functional lactic acid bacteria LP1 is expected to regulate inflammation resulting from high energy feeding, and this probiotic could be applied to support inflammatory regulation in high-yield dairy cows.