Lipopolysaccharide-Induced Reductions in Body Weight Gain and Feed Intake Do Not Reduce the Efficiency of Arginine Utilization for Whole-Body Protein Accretion in the Chick

The effects of repeated injections of 400 μg Escherichin coli lipopolysaccharide (LPS) on chick performance from 11 to 22 d posthatching were examined in chicks fed casein-based diets containing graded levels of arginine. Administration of LPS reduced (P < 0.05) weight gain, feed intake, and protein accretion, and there was a tendency (P = 0.07) for LPS administration to be more growth-depressing at the higher than at the lower levels of supplemental arginine. Regression analysis of protein accretion for the first three doses of arginine indicated that protein accretion was a linear (P < 0.01) function of supplemental arginine intake for both saline-injected (r² = 0.94) and LPS-injected (r² = 0.93) chicks. Slopes of the best-fit regression lines for both treatment groups were equal, indicating that arginine utilization for protein accretion was not affected by LPS administration. The dietary arginine concentration required to maximize weight gain and feed efficiency was unaffected by LPS administration, with both saline- and LPS-injected chicks reaching plateaus in weight gain and feed efficiency at 0.90 and 0.98% digestible arginine, respectively.