Short communication: Enhancing dietary cation-anion difference reshaped the distribution of endotoxin across different biofluids and influenced inflammatory response in dairy cows exposed to heat stress

ABSTRACT The objective of the present study was to investigate the alterations of lipopolysaccharide (LPS) endotoxin across four different biofluids (i.e., rumen fluid, blood plasma, milk, and urine) and LPS-related inflammation responses in Holstein dairy cows under heat stress through the regulation of dietary cation-anion difference (DCAD). Eight lactating Holstein dairy cows were randomly assigned in a 2 × 2 crossover design to either a control DCAD diet (CON: 33.5 mEq/100 g DM) or a high DCAD diet (HDCAD: 50.8 mEq/100 g DM), and each experimental period lasted for 21 days. Samples of rumen fluid, blood plasma, milk, and urine were collected on the last day of each period and the concentrations of LPS endotoxin in those samples were measured afterwards. In addition, the concentrations of pro-inflammatory indicators related to LPS in the blood serum were also determined. Heat stress was more severe in period I, during which a higher (P