Subacute ruminal acidosis (SARA) affects fermentation and endotoxin concentration in the ruminal fluid and relative expression of the CD14/TLR4/MD2 genes involved in lipopolysaccharides systemic immune response in dairy cows

摘要

It is common practise to feed high-yielding dairy cows high-grain diets. However, the disproportion between a high proportion of rapidly fermented carbohydrates and low physically effective NDF may cause impaired ruminal health through variation in the VFA and decreased ruminal fluid pH, which leads to SARA (Humer, 2017). Several studies have investigated the ethology and pathophysiology of SARA (Khafipour, 2009; Danscher, 2016), but still no clear definition of SARA exists. Additionally, current recommendations for the diagnosis of SARA in the dairy herds are mainly based on ruminal pH measured in fluid sampled by rumenocentesis (Nordlund and Garett, 1994). However, many authors have suggested that the use of ruminal pH as the only indicator of SARA should be avoided. The first objective of our study was to investigated the effects of SARA on fermentation, ruminal free LPS, and expression of the CD14/TLR4/MD2 complex involved in the systemic immune response in dairy cows. The second objective wasa study of whether increased expression of the LPS receptor complex led to increases in the concentrations of plasma HDL and serum Ca.