EFFECT OF FEEDING REGIMEN ON CONCENTRATION OF FREE ENDOTOXIN IN RUMINAL FLUID OF CATTLE

The influence of concentrate diets on endotoxin concentration in steri le filtrate of ruminal fluid was assessed in ruminally fistulated Jers ey cows. Three cows underwent a change in diet from hay to a diet cont aining 3.0 kg and 14 d later 6.0 kg of a 12% CP concentrate. The cows had free access to water and a mineral-stone. A modified Limulus Amoeb ocyte Lysate technique was used for the endotoxin analyses. The endoto xin concentration in the ruminal fluid of cows fed on hay were 148 +/- 84 and 118 +/- 50 endotoxin units (EU)/mL (mean +/- SD) on two separa te days and increased from the 2nd d of supplementation with 3.0 kg of concentrate to 408 +/- 198 EU/mL on d 5. When the cows were fed 6.0 k g of concentrate, the endotoxin concentrations increased to 1,599 +/- 944 EU/ mL. To assess the influence on the ruminal endotoxin concentra tion of an adaptation of the ruminal environment to concentrate before hyperalimentation, four ruminally fistulated Jersey cows previously f ed either hay or a high-concentrate diet for 1 mo were hyperalimented with 60 to 70 g of barley per kilogram BW. A relative increase in rumi nal endotoxin concentration was determined only in the two cows previo usly fed concentrates. The results show that high-concentrate diets do not consistently relate to increases of ruminal endotoxin concentrati ons.