Intelligent Equipment Research Center, Beijing Academy of Agriculture and Forestry Sciences, Beijing 100097, China.
Department of Infectious Diseases and Public Health, City University of Hong Kong, Hong Kong SAR, China.
J Dairy Sci. 2022 Oct;105(10):8497-8508. doi: 10.3168/jds.2022-21892. Epub 2022 Aug 12.
The 3 branched-chain AA (BCAA), Val, Leu, and Ile, are essential AA used by tissues as substrates for protein synthesis and energy generation. In addition, BCAA are also involved in modulating cell signaling pathways, such as nutrient sensing and insulin signaling. In our previous study, dietary BCAA supplementation was shown to improve protein synthesis and glucose homeostasis in transition cows. However, a more detailed understanding of the changes in metabolic pathways associated with an increased BCAA availability is desired to fine-tune nutritional supplementation strategies. Multiparous Holstein cows (n = 20) were enrolled 28 d before expected calving and assigned to either the BCAA treatment (n = 10) or the control group (n = 10). Cows assigned to BCAA were fed 550 g/d of rumen-protected BCAA mixed with 200 g/d of dry molasses from calving until 35 DIM, whereas the cows assigned to the control were fed only 200 g/d of dry molasses. Serum samples were collected on d 10 before expected calving, as well as on d 4 and d 21 postpartum. Milk samples were collected on d 14 postpartum. From a larger cohort, we selected 20 BCAA-supplemented cows with the greatest plasma urea nitrogen concentration, as an indicator for greater BCAA availability, for the metabolomics analysis herein. Serum and milk samples were subjected to a liquid chromatography-mass spectrometry-based assay, detecting and measuring the abundance of 241 serum and 211 milk metabolic features, respectively. Multivariable statistical analyses revealed that BCAA supplementation altered the metabolome profiles of both serum and milk samples. Increased abundance of serum phosphocholine and glutathione and of milk Val, Ile, and Leu, and decreased abundance of milk acyl-carnitines were associated with BCAA supplementation. Altered phosphocholine and glutathione abundances point to altered hepatic choline metabolism and antioxidant balance, respectively. Altered milk acyl-carnitine abundances suggest changes in mammary fatty acid metabolism. Dietary BCAA supplementation was associated with a range of alterations in serum and milk metabolome profiles, adding to our understanding of the role of BCAA availability in modulating dairy cow protein, lipid, and energy metabolism on a whole-body level and how it affects milk composition.
3 支链氨基酸（BCAA），缬氨酸、亮氨酸和异亮氨酸，是组织用作蛋白质合成和能量生成底物的必需氨基酸。此外，BCAA 还参与调节细胞信号通路，如营养感应和胰岛素信号。在我们之前的研究中，膳食 BCAA 补充被证明可以改善过渡奶牛的蛋白质合成和葡萄糖稳态。然而，为了优化营养补充策略，更详细地了解与增加 BCAA 可用性相关的代谢途径的变化是必要的。将 20 头经产荷斯坦奶牛（n = 20）在预计分娩前 28 天入组，并分为 BCAA 处理组（n = 10）或对照组（n = 10）。从分娩开始至 35 DIM，给分配到 BCAA 的奶牛喂食 550 g/d 的瘤胃保护 BCAA 与 200 g/d 的干糖蜜混合，而分配到对照组的奶牛仅喂食 200 g/d 的干糖蜜。在预计分娩前 10 天、产后第 4 天和第 21 天采集血清样本。产后第 14 天采集奶样。在更大的队列中，我们选择了 20 头具有最大血浆尿素氮浓度的 BCAA 补充奶牛，作为本代谢组学分析中更大 BCAA 可用性的指标。对血清和奶样进行了基于液相色谱-质谱的检测，分别检测和测量了 241 种血清和 211 种奶代谢特征的丰度。多变量统计分析显示，BCAA 补充改变了血清和奶样的代谢组图谱。血清中磷酸胆碱和谷胱甘肽以及奶中缬氨酸、异亮氨酸和亮氨酸的丰度增加，奶中酰基辅酶 A 的丰度降低与 BCAA 补充有关。磷酸胆碱和谷胱甘肽丰度的改变分别表明肝脏胆碱代谢和抗氧化平衡的改变。奶中酰基辅酶 A 丰度的改变表明乳腺脂肪酸代谢的改变。膳食 BCAA 补充与血清和奶代谢组图谱的一系列变化有关，这增加了我们对 BCAA 可用性在调节奶牛整体蛋白质、脂质和能量代谢以及对奶组成的影响的理解。
