Responses of broilers to sodium bicarbonate supplementation of diets containing varying arginine : lysine ratios

Abstract

Interactions of sodium bicarbonate (NaHCO₃) with dietary arginine : lysine (arg : lys) ratios at thermoneutral (21˚C) and high (31˚C) temperatures were investigated with 21–42-day-old broilers fed diets containing increasing concentrations of arginine to produce arg : lys ratios of 1.05, 1.15, 1.25, and 1.35, with and without 16 g NaHCO₃/kg. Consistent positive relationships were observed between increasing dietary arg : lys ratios and improved food intake and weight gain at 31˚C with broilers fed diets without NaHCO₃. The primary response to increasing dietary arg: lys ratio in broilers receiving NaHCO₃ was increased food intake. This gave corresponding increases in weight gain at 31˚C, but not at 21˚C. Increases in dietary arg : lys ratio increased plasma arginine, ornithine, and arg: lys ratio but had little effect on plasma lysine concentrations. NaHCO₃ alone had no direct effect on plasma amino acid patterns but was important in potentiating the elevated plasma arg : lys ratio responses observed at 31˚C in broilers receiving NaHCO₃ in their diet. The results indicate important interrelationships exist between dietary amino acids and electrolytes, and the existence of a nutritional requirement for bicarbonate at high temperatures.