М. Н. Хамви The aim of the study was to comprehensively assess the effect of different increased doses (4 to 7 times the recommended level) of an exogenous protease complex (0, 500, and 1000 g/t) in low-protein diets containing 6% feather meal on productivity and proteolytic activity in the gastrointestinal tract of broilers. The experiment was carried out on 400 day-old Ross 308 broilers (44 days of age). The birds were divided into four groups: control (high-protein diet), experimental groups (low-protein diets balanced for amino acids) without proteases (Exp-I), with the addition of 500 g/t (Exp-II) and 1000 g/t (Exp-III) of a combinatorial protease complex. It was found that the use of proteases at doses of 500 and 1000 g/t significantly increased final body weight by 3.2% (p<0.05), reduced feed conversion ratio by 3.0% (p<0.05), and increased the European Production Efficiency Factor by 10.8–12.1% (p<0.05). The maximum dose (1000 g/t) increased proteolytic activity in the jejunal and ileal digesta by 24.3–26.9% (p<0.001) activated brush border peptidases by 70.3% (p<0.05), without significant changes in pancreatic protease activity. Withdrawal of enzymes from the finisher diets revealed a prolonged effect: in the Exp-III group, proteolytic activity in the ileum remained comparable to that in the duodenum, indicating an equalisation of the proximal-distal proteolysis gradient. The proposed strategy combining reduced crude protein level, crystalline amino acid balancing, inclusion of feather meal (6%) and megadoses of proteases (1000 g/t) allows for effective keratin utilization, improves nutrient digestibility and enhances broiler performance without additional stress on the pancreas/
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