DIETARY INTERACTIONS BETWEEN LYSINE AND THREONINE IN BROILERS

Two experiments were conducted to evaluate the effects of two dietary levels of lysine and four dietary levels of threonine in a factorial a rrangement on broiler growth, carcass traits, and immunity. In both ex periments, 120 broilers were allocated to each of 56 floor pens (6,720 total broilers). In Experiment 1, two levels of lysine (1.10 and 1.20 % of diet) and four levels of threonine (0.68, 0.74, 0.80, and 0.86% o f diet) were fed to broilers from 1 to 18 d of age in a sorghum-peanut meal diet. Body weight gain, feed:gain, mortality, and cellular and h umoral immunity were measured. In Experiment 2, all broilers received a common basal diet up to 18 d of age. Experimental diets were fed fro m 18 to 34, 34 to 44, and 44 to 54 d of age. Two levels of lysine [100 and 105% of NRC (1994) recommendations] and four levels of threonine [83, 92, 100, and 108% of NRC (1994) recommendations] were included in the experimental diets for each age group (seven replications per tre atment). The diets consisted of wheat (soft), corn gluten meal, soybea n meal, and meat and bone meal. Weight gain, feed:gain, mortality, and carcass traits were measured at 54 d of age.