Department of Reproduction, Obstetrics and Herd Health, Ghent University, B-9820 Merelbeke, Belgium.
Royal Veterinary College, NW1 0TU London, United Kingdom.
J Dairy Sci. 2019 Mar;102(3):2631-2644. doi: 10.3168/jds.2018-15533. Epub 2019 Jan 26.
The aim of this study was to describe metabolism of early-lactation dairy cows by clustering cows based on glucose, insulin-like growth factor I (IGF-I), free fatty acid, and β-hydroxybutyrate (BHB) using the k-means method. Predictive models for metabolic clusters were created and validated using 3 sets of milk biomarkers (milk metabolites and enzymes, glycans on the immunogamma globulin fraction of milk, and Fourier-transform mid-infrared spectra of milk). Metabolic clusters are used to identify dairy cows with a balanced or imbalanced metabolic profile. Around 14 and 35 d in milk, serum or plasma concentrations of BHB, free fatty acids, glucose, and IGF-I were determined. Cows with a favorable metabolic profile were grouped together in what was referred to as the "balanced" group (n = 43) and were compared with cows in what was referred to as the "other balanced" group (n = 64). Cows with an unfavorable metabolic profile were grouped in what was referred to as the "imbalanced" group (n = 19) and compared with cows in what was referred to as the "other imbalanced" group (n = 88). Glucose and IGF-I were higher in balanced compared with other balanced cows. Free fatty acids and BHB were lower in balanced compared with other balanced cows. Glucose and IGF-I were lower in imbalanced compared with other imbalanced cows. Free fatty acids and BHB were higher in imbalanced cows. Metabolic clusters were related to production parameters. There was a trend for a higher daily increase in fat- and protein-corrected milk yield in balanced cows, whereas that of imbalanced cows was higher. Dry matter intake and the daily increase in dry matter intake were higher in balanced cows and lower in imbalanced cows. Energy balance was continuously higher in balanced cows and lower in imbalanced cows. Weekly or twice-weekly milk samples were taken and milk metabolites and enzymes (milk glucose, glucose-6-phosphate, BHB, lactate dehydrogenase, N-acetyl-β-d-glucosaminidase, isocitrate), immunogamma globulin glycans (19 peaks), and Fourier-transform mid-infrared spectra (1,060 wavelengths reduced to 15 principal components) were determined. Milk biomarkers with or without additional cow information (days in milk, parity, milk yield features) were used to create predictive models for the metabolic clusters. Accuracy for prediction of balanced (80%) and imbalanced (88%) cows was highest using milk metabolites and enzymes combined with days in milk and parity. The results and models of the present study are part of the GplusE project and identify novel milk-based phenotypes that may be used as predictors for metabolic and performance traits in early-lactation dairy cows.
本研究旨在通过使用 k 均值法根据葡萄糖、胰岛素样生长因子 I (IGF-I)、游离脂肪酸和β-羟丁酸 (BHB) 将奶牛聚类，从而描述奶牛的早期泌乳代谢。使用 3 组牛奶生物标志物（牛奶代谢物和酶、牛奶免疫球蛋白 G 部分上的聚糖和牛奶中傅里叶变换中红外光谱）创建和验证代谢群集的预测模型。代谢群集用于识别代谢谱平衡或不平衡的奶牛。在产犊后 14 和 35 天，测定血清或血浆中的 BHB、游离脂肪酸、葡萄糖和 IGF-I 浓度。具有良好代谢谱的奶牛被归为“平衡”组（n = 43），并与被归为“其他平衡”组的奶牛（n = 64）进行比较。具有不良代谢谱的奶牛被归为“不平衡”组（n = 19），并与被归为“其他不平衡”组的奶牛（n = 88）进行比较。与其他平衡奶牛相比，平衡奶牛的葡萄糖和 IGF-I 水平更高。与其他平衡奶牛相比，平衡奶牛的游离脂肪酸和 BHB 水平更低。与其他不平衡奶牛相比，不平衡奶牛的葡萄糖和 IGF-I 水平更低。与其他不平衡奶牛相比，不平衡奶牛的游离脂肪酸和 BHB 水平更高。代谢群集与生产参数有关。平衡奶牛的脂肪和蛋白质校正乳产量的日增加量呈上升趋势，而不平衡奶牛的日增加量更高。平衡奶牛的干物质摄入量和干物质摄入量的日增加量较高，而不平衡奶牛的干物质摄入量较低。平衡奶牛的能量平衡持续较高，而不平衡奶牛的能量平衡持续较低。每周或每两周采集一次牛奶样本，并测定牛奶代谢物和酶（牛奶葡萄糖、葡萄糖-6-磷酸、BHB、乳酸脱氢酶、N-乙酰-β-D-氨基葡萄糖苷酶、异柠檬酸）、免疫球蛋白 G 聚糖（19 个峰）和傅里叶变换中红外光谱（1060 个波长减少到 15 个主成分）。使用具有或不具有额外奶牛信息（产犊天数、胎次、产奶量特征）的牛奶生物标志物来创建代谢群集的预测模型。使用牛奶代谢物和酶结合产犊天数和胎次预测平衡（80%）和不平衡（88%）奶牛的准确率最高。本研究的结果和模型是 GplusE 项目的一部分，确定了新的牛奶表型，可作为早期泌乳奶牛代谢和性能特征的预测因子。
