UTTAR PRADESH JOURNAL OF ZOOLOGY

This experiment is aimed to study the effect of non-starch polysaccharide-degrading enzyme “β-mannanase” on alleviating the negative effects of dietary mannans on the gut health and immunity of broilers fed a low-energy diet. A Six-week experiment was conducted in deep litter housing system on total 300, day-old straight-run broiler chicks (Cobb-430Y strain) randomly divided into five groups, containing 60 chicks per group, with three replicates of 20 chicks in each. The diets were positive control (PC): Standard control diet, Negative Control-1 (NC1): 75 kcal/kg less ME than standard diet, Negative Control-2 (NC2): 100 kcal/kg less ME than standard diet, NC1 + BM: NC1 + 100g /ton β-mannanase, and NC2 + BM: NC2 + 100g /ton β-mannanase (Natupulse^® TS). The broilers were fed with corn-soybean meal-based diet in pre-starter (0-14 days), starter (15-28 days), and finisher (29-42 days) phases. The diets formulated were non-isocaloric and iso-nitrogenous in nature. The pre-starter, starter, and finisher diets of PC contained 3,000, 3,125, and 3,250 kcal/kg metabolic energy (ME); and 22.50, 21, 19.5% crude protein, respectively. The jeunal histomorphology (Vill height, width, crypt depth, villi height to crypt depth ratio, and goblet cell count), Jejunal microbial count (Lactobacillus, E. coli and Total Viable Count) and relative weights of immune organ (Spleen, Bursa of Fabricius and Thymus) were studied on 35^th day age.   

The β-mannanase supplementation in low-energy diet significantly (P < .05) lowered crypt depth, increased villus height: crypt depth ratio and lowered goblet cell count in the Jejunum compared to PC and negative controls (NC1 and NC2), indicating that β-mannanase helps to improve gut health. A significant (P < .05) decrease in goblet cell count in Jejunal villi of the small intestine in β-mannanase supplemented groups indicated that the β-mannanase alleviates the negative effects of mannans-containing diets that might help in reducing intestinal viscosity. The β-mannanase addition significantly improved the weights of immune organs like the spleen, bursa of fabricius, and thymus, indicating a better immune response. The β-mannanase significantly (P < .01) improved Lactobacillus count and decreased the E coli count of jejunal content. Results conclude that supplementation of β-mannanase @ 100g/ton in low-energy diets (75 and or 100 kcal/kg less ME) alleviates negative effects of dietary mannans and significantly improves gut health and immunity.