Abstract
This study examines the supplementation of soy protein concentrates (SPC) in the diet of straight run broiler chickens and its effect on their immunity and productive performance. Eight hundred Ross 308 mixed chicks were randomly assigned to four varied dietary treatments (200 birds each), four replicates per dietary treatment (50 chicks/replicate). The diets were a control without supplement (T(0)) or supplemented with T(1) (7g), T(2) (8g), and T(3) (9g)/bird of 5% SPC, which replaced SBM in the basal starter diet at a rate of 5% (W/W). Each bird received a total of 300 g of the starter diet during the first 12 days of rearing and then was fed ad-libitum grower and finisher diets without SPC inclusion for 35 d. On day 35, 2 birds/replicate (8/treatments, 32 birds) were randomly selected and slaughtered for carcass evaluation. Results showed that 9g showed the lowest body weight (P < 0.05) compared to other SPC treatments. SPC addition did not improve performance. 8g had significant (P < 0.05) dressing %. Carcass characteristics were not affected by SPC. Newcastle disease blood titers showed significantly higher protection for 9g and 8g SPC on d 20. Avian Influenza blood titers gave the best results with (9g) at d 30, while Infectious Bursal Disease and Infectious Bronchitis blood titers were not affected by changing dietary levels with SPC. In conclusion, results indicated that supplementing soya protein concentrates to broiler chickens in the starter period has an effect on body weight and dressing %, and that it enhanced immunity against Newcastle and Avian influenza diseases.