EFFECT OF ALTERING THE SOURCE OF NONESSENTIAL NITROGEN ON PERFORMANCE AND CARCASS COMPOSITION OF THE BROILER CHICK

Male broilers were fed diets containing 14, 18 or 22% crude protein (CP) and 10.88, 12.13 or 13.39 MJ kg −1 metabolizable energy (ME) to 3 wk of age. For each level of CP and ME, three diets were formulated so that excess nitrogen arose mainly from nonessential amino acids (NEAA), essential amino acids (EAA) or both. The source of nitrogen excess had no effect on any of the parameters measured in birds fed the 18 and 22% CP diets. However, at 14% CP and over all energy levels, excess nitrogen in the form of EAA gave rise to superior results with regard to weight gain, feed conversion efficiency and carcass protein when compared to those diets where the excess nitrogen arose mainly from NEAA sources. Increasing dietary energy reduced the effect that source of nonessential nitrogen had on weight gain, feed conversion efficiency and carcass protein deposition at 14% CP. Key words: Amino acids, energy, protein, broilers