Effects of gelatin as an alternative protein source and mono-component protease supplementation on growth performance, viscosity, digestibility and microbial population of ileal digesta, digestive tract traits and gut morphology of broiler chickens

An experiment was conducted to investigate the effects of using gelatin as a partial protein source and protease in broilers diets. The experiment was carried out as a factorial arrangement, containing two levels of protease (0 and 200 gs per ton of diet) and four levels of gelatin (0, 2.82, 4.23 and 5.64% of the diet replacing 12.5, 18.75 and 25% of the SBM protein, respectively) with 6 replicates and 15 chicks in each pen. Body weight, feed intake and FCR were measured at day 7, 21 and 35. Ileal digesta viscosity, ileal morphology and ileal coliform and lactobacilli population were measured at day 35. In addition, apparent protein digestibility was determined between 28 and 35 days of age. Results show that the highest inclusion rate of gelatin decreased body weight and feed intake (P < 0.05) while, addition of enzyme increased both feed intake and body weight (P < 0.05). Gelatin inclusion deteriorated the FCR whereas supplementation of proteases improved it (P < 0.05). Inclusion of gelatin increased ileal viscosity (P < 0.05) and depressed protein digestibility (P < 0.05). Use of the protease decreased viscosity (P < 0.05) and increased protein digestibility (P < 0.05). Treatments containing gelatin showed a reduction of coliform (P < 0.05) and an enhancement of lactobacilli population of ileal digesta (P < 0.05). Using protease had similar effects on microbial population of ileal digesta. Results of this study shows that using gelatin as a partial replacement of soybean meal protein can be recommended if the inclusion levels are limited to 12.5% or less.