METHODS: A total of 480 day-old male broiler chicks were randomly assigned to eight dietary treatments in a 4×2 factorial arrangement. The main effects were CP level (21.0%, 19.7%, 18.5%, or 17.2% from 1 to 21 days and 19.0%, 17.9%, 16.7%, or 15.6% from 22 to 35 days) and protease enzyme supplementation (0 ppm or 500 ppm). All experimental diets were fortified with synthetic feed-grade lysine, methionine, threonine and tryptophan to provide the minimum amino acid recommended levels for Cobb 500.
RESULTS: Reducing dietary CP linearly reduced (p<0.05) growth performance, serum albumin, total protein, and carcass traits and increased (p<0.05) serum triglycerides and abdominal fat. There was no consistent effect of reducing dietary CP on morphological parameters of the intestine and on the pancreatic and intestinal endogenous protease activity (p>0.05). Protease supplementation improved (p<0.05) feed conversion ratio, body weight gain, carcass yield and intestinal absorptive surface area.
CONCLUSION: Protease supplementation, as measured by growth performance, intestinal morphology and carcass yield, may alleviate the detrimental effects of low protein diets in broiler chickens.