Effect of Low Protein-Methionine-and-Lysine-Supplemented Diets on Performance, Immune Response and Carcass Characteristics in Broilers
Two experiments were conducted to investigate the effect of supplementing low CP diets with methionine and lysine on broiler performance, carcass measure and their immune response against Infectious Bursa Disease (IBD) virus. In Experiment 1, ten diets were formulated. Diet 1 (control diet) contained 23.0% CP and 0.6% methionine. The remaining 9 test diets were formulated to contain 20, 17 and 14% CP each with 0.6, 1.0 and 1.4% methionine in a 3x3 factorial arrangement. Three hundred and twenty 1-d-old broiler chicks were weighed and randomly allocated to the 10 diets with four replicates and eight birds each. In Experiment 2, 10 diets were also formulated. Diet 1 (control diet) contained 23% CP and 1.2% lysine. The rest 9 diets were similar to those in Experiment 1 but lysine was used to supplement the CP at levels 1.2, 1.6 and 2.0% inclusion. One hundred and sixty 1-d-old broiler chicks were weighed and randomly allocated into the 10 diets with four replicates of four birds each. In Experiment 1, Body Weight Gain (BWG), Feed Intake (FI) and Feed Conversion Ratio (FCR) in control and 20% CP diet with 1.0 methionine were similar. Dressed weight, weights of thigh, breast, and drum stick in the control and 1.0% methionine diets were similar There was no effect of methionine, CP or their interaction on the antibody titre against IBD. In Experiment 2, increasing lysine and decreasing CP significantly (P<0.01) reduced BWG and FI, but 1.6% lysine had similar effect on FCR as the control diet. There was no effect of lysine, CP or their interaction on the antibody titre against IBD virus. Results suggest that supplementation of broiler diets of CP less than 23% with 1.0% methionine and 1.6% lysine resulted in similar performance as control diet and the bird’s immune response against IBD virus was not compromised.
Keywords: Immune response, Ideal methionine to lysine ratio, Performance indices, Antibodies, Carcass characteristics.