An experiment was conducted to evaluate the effect of lysine supplementation in low protein diets on the performance of growing broilers. Six broiler starter diets designated as A, B, C, D, E and F were formulated in such a way that diets A & B had CP 23%, diets C & D had CP level 21%, while diets E & F had CP 19%. Each pair of diets was supplemented with two levels of lysine i.e. 1.1 and 1.2%. These experimental diets were fed to the birds from day 0 to 28. Results indicated that both CP and lysine levels had significant effect on mean body weight gains. Maximum average weight gain (1244 gms) was observed in birds fed diets with 19% CP and 1.2% lysine. It was observed that there were significant differences in feed intake among diets. Minimum feed consumption (1900.24 gms) was observed in birds fed on diet containing 23% CP and 1.1% lysine. Protein and lysine levels had non-significant effect on the mean FCR of the diets. It was concluded that CP levels in the diets of the broilers could be reduced from 23 to 19%, when considering in terms of FCR, provided that their lysine levels are higher than NRC recommended levels.

Key words: Lysine, Broilers, Low protein, Weight gain, Feed efficiency.