Response of Cobb and Sasso Broilers to Feeding Restriction and Tryptophan Supplementation

An experiment was conducted to investigate the influence of early feed restriction and feeding Tryptophan on growth performance, kidney and liver functions of two broiler breeds. 180 Cobb 500 and 180 Sasso T44 chicks were divided randomly at 14 days of age according to feeding regime into three main groups, 1. Third week feed restricted group, 2. Fourth week feed restricted group and 3. Control group (ad libitum feeding). Each group was subdivided into 1. Tryptophan supplemented group (0.02%) and 2. Tryptophan free group, birds in each final group subdivided into 3 replicates (10 birds / replicate). Cobb 500 broilers recorded significantly higher body weight and weight gain throughout the experiment than that of Sasso T44 (P 0.05), however, feed restriction of Cobb 500 during 3rd and 4th week of age was significantly lower than Sasso T44 (1.62 and 1.47 vs. 1.78 and 1.73). Early feed restriction and Tryptophan supplementation improved significantly final body weight, weight gain and feed conversion compared to ad libitum feeding and Tryptophan free groups. Dressing % and carcass characteristics were significantly better in Cobb 500 than Sasso T44, in 3rd week feed restriction than 4th week feed restriction and ad libitum feeding and in Tryptophan supplemented than Tryptophan free groups. Although there were some differences in measured blood parameters, kidney and liver enzymes between the two broiler breeds, the different feeding regimes and two Tryptophan managements all measured values were within the normal reference range. In conclusion Cobb 500 broilers were recommended for meat production, early feeding restriction for a week and Tryptophan supplementation for better growth performance and carcass traits without affecting kidney and liver function.