Optimal glycine allowance levels in low-protein diets and the dynamic requirement model for broilers

作者：Yongfa Liu, Yizhu Zhao, Jiran Ma, Siyan Guo, Xuyang Gao, Bin Wang, Lu Gong, Zengpeng Lv, Yuming Guo · 发表于：Poultry Science · 年份：2024 · DOI：10.1016/j.psj.2024.104255 · 被引用次数：7 · 研究领域：Animal Nutrition and Physiology、Aquaculture Nutrition and Growth、Biochemical Analysis and Sensing Techniques

This study aimed to investigate the effects of different glycine levels in low-protein diets on the growth, nitrogen deposition, and expression of intestinal amino acid and glucose transporters in broilers from 29 to 42 d of age, in order to determine the optimal glycine supplementation level. A total of 240 male broilers at 29 days old were randomly assigned to 5 groups: the control group with a crude protein level of 20%, and experimental groups with low-protein diets (LP130) containing 18% crude protein, supplemented with glycine to achieve standardized ileal digestible ( SID ) glycine + serine to lysine ratios of 134% (LP134), 140% (LP140), and 145% (LP145). The results showed that the LP134 group had similar growth performance and slaughter performance compared to the control group ( P > 0.05), whereas other low-protein diet groups had significantly lower growth performance ( P < 0.05). Regression analysis determined that the optimal ratio for SID glycine + serine to lysine was 137%. A dynamic model for glycine + serine requirements was established through binary regression analysis: y = 599.051 × BW ^0.75 + 8.381 × ADG (R 2 = 0.998, P < 0.001). Feeding LP134, LP140, and LP145 diets significantly improved nitrogen deposition rates in broilers ( P < 0.05). Low-protein diets significantly upregulated mRNA levels of b 0,+ AT, EAAT3, and SGLT1 genes in the duodenum ( P < 0.05). In conclusion, appropriate glycine supplementation in low-protein diets can enhance growth perform...