Effect of dietary protein composition on the optimum time of change from starter to finisher diets for broilers

Abstract

Three experiments were conducted to examine the amino acid requirements of broilers at various growing stages to eight weeks of age, and the optimum time of change to finisher diets. The practical diets contained balanced proportions of ten essential amino acids (EAA) and were expressed collectively as per cent of diet. Protein composition influenced the optimum time of change to finisher diets. With males, the EAA concentrations of diets determined the optimum time of change. Optimum conditions to maximize growth and feed utilization efficiency were obtained when males were fed 7.6 per cent EAA in an 18.6 per cent protein starter diet for two weeks, followed by a finisher diet having 6.5 per cent EAA in 16.6 per cent protein to eight weeks of age. Feeding a lower concentration of EAA in the finisher diet was acceptable if birds were fed the starter diet for longer time. Non-essential amino acid (non-EAA) content of diets influenced the optimum time of change from starter to finisher diets for female chicks, The female chicks required a higher ratio of non-EAA to EAA in their diets after three weeks of age. Further examination of the requirements for non-EAA in diets where excesses of EAA are eliminated is required.