Effects of Salmonella typhimurium lipopolysaccharide on broiler chickens.

The effects of Salmonella typhimurium lipopolysaccharide (LPS) on the physiology of 3-wk-old broiler chickens were studied at 12, 24, and 48 h after a single intravenous injection of saline or LPS. Lipopolysaccharide elevated cloacal temperature by 3 h after injection, induced a diuretic response, and decreased BW gain. An increase in the relative liver weight was evident in LPS-treated birds at all time intervals, whereas a decrease in the relative weight of bursa of Fabricius was observed only at the 48-h time point. The plasma interleukin (IL)-6 and the blood heterophil concentrations were elevated at 12 and 24 h following LPS administration. These changes were not observed in control chickens or in LPS-treated chickens at 48 h. A decrease in the blood glucose concentration in LPS-treated birds at 12 h was accompanied by an elevation in the blood phosphate level. An increase in total plasma protein concentration was observed only at 24 and 48 h after LPS treatment. Comparative SDS-PAGE analysis of plasma proteins from these birds under nonreducing conditions showed some quantitative differences in four bands of proteins between saline and LPS-treated chickens. A protein corresponding to an approximate molecular weight (MW) of 65 kDa increased in LPS-treated chickens, and three other proteins with MW of approximately 39, 49, and 56 kDa showed reductions in concentration compared with saline-treated controls. These results show that LPS induces a number of physiological changes that may be responsible for the regulation of the acute phase response in chickens.