The experiment was conducted to determine the effect of dietary methionine + cystine (met + cys) requirement of 1-to-21-day-old broiler chicks on thermoneutral environment. Four hundred Avian Farm male broiler chicks were assigned to a randomized experimental design with five treatments (0.756, 0.810, 0.866, 0.920, and 0.976% of met + cys), eight replicates of ten birds. Weight gain (WG), feed:gain ratio, met + cys intake, protein deposition of absolute weights of liver, gizzard, and lung and relative weights of lung […]