In this study 288 broilers were used in a factorial 2 x 2 (completely randomized) design with 9 replicates of eight birds each. The broilers were fed a control diet (22% crude protein) or high protein diet (30%) with or without the supplementation of 0.5 kg/t protease (CIBENZA DP100, Novus International Inc.). All diets contained rye and wheat and the animals were subject to a coccidiosis challenge (subclinical enteritis model). Evaluations were done on ileal clostridium perfringens counts (15 days old) as well as on intestinal histology (14 days), the serum glycoprotein alpha 1-acid as an indicator of immune function (22 days), and the broilers performance (28 days).
In the second trial, three diets were fed (C) control, (BPAA) low crude protein and amino (-7%) and protease BPAA + Cibenza DP100. The animals were subjected to two rearing management regimes:
- (Normal) standard placing density and feeding conditions
- (Stress) high placing density and 8 hours of darkness
The performance parameters were evaluated at specific times, and the data was analyzed using procedures suitable for a randomized block design of the SAS® statistical program. The four diets with reduced protein were also analyzed in a factorial arrangement to evaluate the effect of stress, and the interaction between protease factors.