Effects of different types of diet on ruminal endotoxin release and immune activation in the mammary gland of dairy cows

摘要

Introduction Feeding dairy cows diets containing high proportions of concentrateto support the high energy and nutrient demands,is associated with a rapid decline in ruminal pH.As a result,subacute ruminal acidosis (SARA) occurs frequently in dairy cows (Nocek,1997;Dong et al.,2011).Meanwhile,the concentration of endotoxin (or lipopolysaccharide,LPS) in the rumen increased in a large amount (Andersen,2003).LPS can be translocated into the bloodstream across the epithelium of the digestive tract wall.As a result,the concentration of blood LPS increases,which can trigger a systemic inflammation (Emmanuel,2008).The immune activation may reduce supply of milk component precursors for milk synthesis by repartitioning more nutrients for synthesis of immune molecules.Our study was then aimed to evaluate the effects of feeding different types of diet with different ingredient compositions and concentrate proportions on ruminal LPSrelease and immune activation in the mammary gland of dairy cows.