AUTHOR=Wang Chaoyong , Yuan Tong , Yang Jing , Zheng Wenxuan , Wu Qilin , Zhu Kaixuan , Mou Xiangyu , Wang Lizhi , Nie Kangkang , Li Xinyun , Zhu Yongwen 

TITLE=Responses of Combined Non-starch Polysaccharide Enzymes and Protease on Growth Performance, Meat Quality, and Nutrient Digestibility of Yellow-Feathered Broilers Fed With Diets With Different Crude Protein Levels

JOURNAL=Frontiers in Veterinary Science

VOLUME=Volume 9 - 2022

YEAR=2022

URL=https://www.frontiersin.org/journals/veterinary-science/articles/10.3389/fvets.2022.946204

DOI=10.3389/fvets.2022.946204

ISSN=2297-1769

ABSTRACT=The aim of this study was to investigate the responses of NSP enzymes and protease combination on growth performance and nutrient utilization in yellow-feathered broilers fed the diets with normal and subnormal CP levels at 1-56 d of age. The experimental design was completely randomized with a 2 × 2 factorial arrangement of treatments. These variables included 2 dietary CP treatments of normal CP level as positive control (PC) and subnormal CP level without extra essential amino acid (AA) supplementation as negative control (NC) and 2 dietary enzyme treatments of no exogenous enzymes and plus exogenous NSP enzymes and protease combination. Each treatment included 6 replicates of 20 birds per pen. The broilers fed the NC diet had lower the final BW and ADG (P < 0.05) at d 1-21, d 22-56 and d 1-56 and lower the F/G at d 22-56 than birds fed the PC diet. Broilers fed the NC diet had higher (P < 0.05) L* and b* values in thigh muscle, crypt depth in duodenum and DM digestibility as well as lower villus height, musculature thicknesses, and villus height: crypt depth in duodenum than birds fed the PC diet. Dietary NSP enzymes and protease combination increased (P < 0.05) ADG and F/G of broilers at d 1-56, and the pH values in breast and thigh muscles as well as the digestibility of DM, GE, CP and most AA of broilers at d 56. Moreover, broilers fed NC diet added with NSP enzymes and protease exhibited the greater improvements in the digestibility of DM, CP and some AA (Asp, Ile, Leu) compared with PC diet. In conclusion, the reducing subnormal CP level in the diet without essential AA supplementation impaired growth performance and meat color of thigh muscle of yellow-feathered broilers. The combination of NSP enzymes and protease supplementation effectively improved the growth performance, meat quality and nutritional value of the corn-soybean meal based diet. In term of the digestibility of DM, CP, and some AA, the magnitude of the responses to exogenous enzyme addition was greater in the low nutritional quality diet with  subnormal CP level.