Goo Doyun, Singh Amit K, Choi Janghan, Sharma Milan K, Paneru Deependra, Lee Jihwan, Katha Hemanth R, Zhuang Hong, Kong Byungwhi, Bowker Brian, Kim Woo Kyun
Department of Poultry Science, University of Georgia, Athens, GA, USA.
US National Poultry Research Center, USDA-ARS, Athens, GA, USA.
Poult Sci. 2024 Dec;103(12):104313. doi: 10.1016/j.psj.2024.104313. Epub 2024 Sep 7.
Balanced ratios of branched-chain amino acids (BCAAs) can enhance chicken growth, immunity, and muscle synthesis. However, these ratios can be affected by changes in crude protein (CP) levels or the substitution of protein sources, leading to BCAA antagonism. This, in turn, can have a negative impact on chicken growth. In Experiment 1, a total of 960 0-d-old male Cobb 500 broilers were divided into 6 treatments with 8 replicates. Three different BCAA ratios were used in High or Low CP diets as follows: 1) Low Leu group (Low level of leucine with increased valine and isoleucine levels), 2) Med Leu group, and 3) High Leu group (High level of leucine with reduced valine and isoleucine levels) for a total of 6 diets. In Experiment 2, a total of 640 0-d-old male Cobb 500 broilers were divided into 4 treatments with 8 replicates. The four diets had either High or Low CP and one of two protein sources with the same medium levels of BCAAs: 1) the soybean meal (SBM) group, which had SBM as the main protein source (protein bound AA), and 2) the wheat middlings with non-bound AAs (WM+AA) group (non-bound AA), which had additional non-bound AAs to replace SBM. The High Leu diet had a negative effect on overall growth performance, carcass weight, breast muscle weight, and body mineral composition compared to the Low Leu and Med Leu groups, particularly in the High CP diet (P < 0.05). The SBM group showed increased growth performance, breast muscle weight, expression levels of genes promoting muscle growth, and improved bone mineral composition compared to the WM+AA group, and the High CP group intensified the negative effect of the WM+AA diet (P < 0.05). In summary, balanced BCAA ratios and SBM-based diets have positive effects on chicken growth and muscle accretion, whereas excessive leucine and non-bound AA levels in the diets may negatively affect growth performance and meat yield in chickens.
支链氨基酸（BCAAs）的平衡比例可以提高鸡的生长速度、免疫力和肌肉合成能力。然而，这些比例会受到粗蛋白（CP）水平变化或蛋白质来源替代的影响，从而导致BCAA拮抗作用。这进而会对鸡的生长产生负面影响。在实验1中，总共960只0日龄雄性科宝500肉鸡被分为6个处理组，每组8个重复。在高或低CP日粮中使用了三种不同的BCAA比例，如下：1）低亮氨酸组（亮氨酸水平低，缬氨酸和异亮氨酸水平升高），2）中等亮氨酸组，3）高亮氨酸组（亮氨酸水平高，缬氨酸和异亮氨酸水平降低），总共6种日粮。在实验2中，总共640只0日龄雄性科宝500肉鸡被分为4个处理组，每组8个重复。这四种日粮具有高或低CP以及两种蛋白质来源之一，且BCAAs水平相同：1）豆粕（SBM）组，以SBM作为主要蛋白质来源（蛋白质结合氨基酸），2）含非结合氨基酸的小麦麸皮（WM+AA）组（非结合氨基酸），该组添加了额外的非结合氨基酸以替代SBM。与低亮氨酸组和中等亮氨酸组相比，高亮氨酸日粮对总体生长性能、胴体重、胸肌重量和身体矿物质组成有负面影响，尤其是在高CP日粮中（P<0.05）。与WM+AA组相比，SBM组的生长性能、胸肌重量、促进肌肉生长的基因表达水平提高，骨骼矿物质组成改善，且高CP组加剧了WM+AA日粮的负面影响（P<0.05）。总之，平衡的BCAA比例和以SBM为基础的日粮对鸡的生长和肌肉生长有积极影响，而日粮中过量的亮氨酸和非结合氨基酸水平可能会对鸡的生长性能和肉产量产生负面影响。
