Duodenal-ileal ratio of digestive enzymes when using different protein supplements in the diet of laying hens

Abstract

Creation of domestic poultry crosses and development of optimal diets for them is an urgent problem, since in vivo studies using fistula technologies are currently few. The present work presents data on determination of duodenal and ileal activity of digestive enzymes when protein additives of vegetable (soybean meal and cake) and animal origin (fish meal and meat and bone meal) are used in the diet of laying hens. Experiments were performed on laying hens (Gallus gallus L.) of Hisex White cross (n=24, K.A. Timiryazev Russian State Agricultural Academy, 2022,2023) with chronic duodenal and ileal fistula. All chickens were divided by random sampling method into 4 groups: 1) 1 control group - received OR (Table 1); 2) 2 experimental group - 1.5% soybean cake was added to the diet instead of soybean meal; 3) 3 experimental group - 1.5% meat and bone meal was added to the diet instead of soybean meal; 4) 4 experimental group - 1.0% fish meal was added to the OR instead of soybean meal. It was found that protein additives are differently hydrolyzed in the intestine of birds and assimilated by the organism. Thus, the breakdown of soy protein is more intensive in cake than in meal due to the increase of trypsin activity in duodenum by 43.6%, and when fish meal is added, the activity of the enzyme increases by 11.8% against meat and bone meal and 101.5% against soy meal. At the same time, protein digestion increased, accompanied by an increase in trypsin activity in blood when soybean cake was used and in urine when fish meal was added to the diet of chickens. With feces the least loss of trypsin is observed in the group that received meat and bone meal supplementation (9.6% of trypsin activity is excreted), then fish meal - 16.8% and soy cake - 21.7% of activity in duodenum, which indicates the efficiency of exo- and endogenous protein utilization by poultry organism.