Effect of protease supplementation on the digestibility of amino acids in animal-origin meals for broiler diets

Enzymes benefit digestion and absorption of the ingredients and their addition to an animal-origin meal (AOM) can improve its nutritional quality. This research aimed to evaluate the effect of protease on nutrient digestibility, amino acids, and metabolism of AOM energy for broilers. Four hundred and eighty broiler chickens were distributed in a completely randomized design (4 × 2 factorial scheme), eight treatments, six replicates containing 10 birds/replicate. Treatments consisted of poultry viscera meal, swine viscera meal (SVM), bovine meat and bone meal, and basal diet; with and without protease addition. Two tests were performed. In the first test, the total excreta collection method was used with birds at 13 to 20 days of age and 25% of the reference feed was replaced by AOM. In the second test, a protein-free diet was administered to birds at 21 to 24 days of age and AOM replaced 25% of the starch. The inclusion of protease increased the apparent metabolizable energy corrected for nitrogen balance of SVM by 15.99% and the apparent metabolizable crude energy by 5.7%, and it also raised the coefficient of true ileal digestibility of the amino acids in the AOMs by 5.67% on average. The inclusion of protease improved the apparent metabolizable crude energy of AOMs, apparent metabolizable dry matter of bovine meat and bone meal, coefficient of true ileal digestibility of essential amino acids, and apparent metabolizable energy corrected for nitrogen balance of SVM. Dietary supplementation of protease may be a potential strategy to improve the digestibility of amino acids for broilers, a possibility of using animal-origin meals as a protein source of diets.