The effect of NSP-degrading enzymes on gut physiology and growth performance of turkeys fed soybean meal and peas-based diets

Abstract

The aim of this study was to determine nutrient digestibility, short chain fatty acids (SCFA) production, bacterial enzyme activities and production performance effects of peas as an alternative dietary protein source. Diets containing peas were fed to growing turkeys for 8 weeks. The experimental design involved two diets, a wheat-soybean meal (SBM) diet and a wheat-SBM-peas diet, each with and without the addition of NSP-degrading enzymes. Peas were added at 300 g/kg at the expense of wheat and SBM. Nutrient digestibility, energy metabolizability and nitrogen retention remained unchanged in all groups. The SBM and peas diets did not affect the final body weights (BW) of birds, but the peas diet significantly (P < 0.05) increased FCR relative to the SBM diet (1.80 vs. 1.74 kg/kg). Enzyme supplementation significantly increased the final BW of turkeys (3.88 vs. 3.75 kg), irrespective of the diet type. A diet by enzyme interaction revealed that during the first 4 weeks of feeding, the enzyme preparation improved feed utilization in the SBM diet but not in the peas diet (1.37 vs. 1.44 kg feed/kg BWG). Enzyme supplementation decreased apparent ileal viscosity (1.60 vs. 1.82 mPas). Cecal ammonia concentrations and the activity of bacterial β-glucosidase, β-xylosidase, and α-arabinofuranosidase decreased significantly in response to peas diets, irrespective of enzyme supplementation. Enzyme supplementation significantly decreased β-glucosidase activity and the SCFA pool in the ceca, regardless of diet type. A diet by enzyme interaction revealed that the NSP-degrading enzyme supplements significantly decreased cecal SCFA concentrations but only in the peas diet (163 vs. 221 μmol/g). Excreta moisture content was significantly lower in the peas diet, regardless of enzyme supplementation and diet type. The Foot Pad Dermatitis (PFD) score was considerably (P < 0.05) reduced in the peas diet (1.43 vs. 1.53–1.60 in the remaining groups). In conclusion, peas could be effectively used in the diets of young growing turkeys at 300 g/kg at the expense of wheat and SBM without any negative effects on the gastrointestinal function and final BW. However, higher FCR values were noted for the peas diet. The benefits of the NSP-degrading enzymes included a decrease in ileal viscosity and excreta moisture content, an increase in cecal butyrate production, and an increase in the final BW of turkeys.