Effect of Dietary Amino Acid Level on Response to Time of Change from Starter to Grower Diets for Broiler Chickens

Abstract

Four trials were conducted to determine the effects of time of changing from starter to grower feed for broilers, as influenced by the amino acid composition of the diet. All diets were formulated to provide a minimum of 100, 110, or 120% of suggested amino acids for male broilers. In the first two trials, starter diets were fed to 17, 21, 25, or 29 days of age. In the third trial, starter diets were fed to 14, 18, 22, or 26 days of age. In the fourth trial, starter diets were fed to 14, 17, 21, or 24 days of age. Grower diets were fed to 40 days and finisher diets to 45 days of age. Broilers from the third trial were processed to examine effects on carcass composition.Although amino acid content of the diet significantly affected a number of live performance and carcass parameters, there was no interaction of time of diet change and amino acid composition of diets. In the first two studies, the 45-day weight of male broilers was reduced significantly (P < .05) when changed from starter to grower diets at 17 days of age. Weight of females, mean weights, total feed consumed, feed utilization, calorie conversion, and mortality were not affected significantly by time of change. In the third and fourth trials, day of change had no significant effects on live performance of broilers. Carcass dressing percentage of males was reduced significantly when starter diets were fed to 29 days; no other effects on carcass characteristics were observed. These data suggest that broilers may be changed from starter to grower diets as early as 14 to 17 days of age, especially if sexes are combined.