Performance, immune response and carcass characteristics of broilers fed with low crude protein and ideal methionine to lysine ratio diets

Abstract

The study was carried out to study the effect of supplementing low crude protein (CP) diet with ideal methionine to lysine ratio (IMLR) on the performance, carcass characteristics and immune response against Infectious Bursa Disease (IBD) and Newcastle Disease (ND) viruses in broilers. Ten Diets Were Formulated: Diet 1 (control diet) contained 23% CP and IMLR of 47%. The remaining 9 test diets were formulated to contain 20, 17 and 14% CP each with 47, 52 and 57% IMLR in a 3x3 factorial arrangement. The experiment was carried out at the pullet unit of the Teaching and Research Farm of the Department of Animal Science, Department of Veterinary Medicine, all at University of Ibadan, Ibadan Nigeria, between February and March 2011. Day-old broiler chicks (160) were wing branded, weighed and randomly allocated into the 10 diets with four replicates of four birds each. The chicks were vaccinated against IBD virus on d 10 and against ND virus on d 16 posthatch via drinking water. Results revealed that the feed intake (FI) in the control and in the 20% CP/47% IMLR (60.27g/b, 57.81g/b) diets were similar. Feed conversion ratio (FCR) in the control and in the 20% CP/47% IMLR (2.65, 2.70) diets were also similar. Breast’s weights in the control and in the 20% CP/52% IMLR diets (148.75, 150.75) were similar. Birds on 17% CP with 52% IMLR (19,637 antibody titre) had the best immune response against IBD virus, while birds on 20% CP with 47% IMLR (1442 antibody titre) diet had the best immune response against ND virus. Results suggest that diets of CP less than 23% with 47 and 52% IMLR for broilers resulted in similar performance as control diet and the bird’s immune response against IBD and ND virus were not compromised.