Department of Clinical Science, Faculty of Veterinary Medicine, University of Tabriz, 516616471 Tabriz, Iran.
Institute of Animal Science, Physiology and Hygiene Unit, University of Bonn, 53115 Bonn, Germany.
J Dairy Sci. 2020 Apr;103(4):3730-3744. doi: 10.3168/jds.2019-17566. Epub 2020 Jan 31.
The transition from late gestation to early lactation is associated with extensive changes in metabolic, endocrine, and immune functions in dairy cows. Skeletal muscle plays an important role in maintaining the homeorhetic adaptation to the metabolic needs of lactation. The objective of this study was to characterize the skeletal muscle metabolome in the context of the metabolic changes that occur during the transition period in dairy cows with high (HBCS) versus normal body condition (NBCS). Fifteen weeks antepartum, 38 pregnant multiparous Holstein cows were assigned to 1 of 2 groups, which were fed differently to reach the targeted BCS and back fat thickness (BFT) until dry-off at -49 d before calving (HBCS: >3.75 and >1.4 cm; NBCS: <3.5 and <1.2 cm). During the dry period and the subsequent lactation, both groups were fed identical diets. The differences in both BCS and BFT were maintained throughout the study. The metabolome was characterized in skeletal muscle samples (semitendinosus muscle) collected on d -49, 3, 21, and 84 relative to calving using a targeted metabolomics approach (AbsoluteIDQ p180 kit; Biocrates Life Sciences AG, Innsbruck, Austria), which allowed for the quantification of up to 188 metabolites from 6 different compound classes (acylcarnitines, amino acids, biogenic amines, glycerophospholipids, sphingolipids, and hexoses). On d -49, the concentrations of citrulline and hydroxytetradecadienyl-l-carnitine in muscle were higher in HBCS cows than in NBCS cows, but those of carnosine were lower. Over-conditioning did not affect the muscle concentrations of any of the metabolites on d 3. On d 21, the concentrations of phenylethylamine and linoleylcarnitine in muscle were lower in HBCS cows than in NBCS cows, and the opposite was true for lysophosphatidylcholine acyl C20:4. On d 84, the significantly changed metabolites were mainly long-chain (>C32) acyl-alkyl phosphatidylcholine and di-acyl phosphatidylcholine, along with 3 long-chain (>C16) sphingomyelin that were all lower in HBCS cows than in NBCS cows. These data contribute to a better understanding of the metabolic adaptation in skeletal muscle of dairy cows during the transition period, although the physiological significance and underlying molecular mechanisms responsible for the regulation of citrulline, hydroxytetradecadienyl-l-carnitine, carnosine, and phenylethylamine associated with over-conditioning are still elusive and warrant further investigation. The changes observed in muscle lysophosphatidylcholine and phosphatidylcholine concentrations may point to an alteration in phosphatidylcholine metabolism, probably resulting in an increase in membrane stiffness, which may lead to abnormalities in insulin signaling in the muscle of over-conditioned cows.
从妊娠后期到泌乳早期的过渡与奶牛代谢、内分泌和免疫功能的广泛变化有关。骨骼肌在维持泌乳代谢需求的同源适应方面起着重要作用。本研究的目的是描述在高体况（HBCS）与正常体况（NBCS）奶牛在过渡期发生代谢变化的情况下，骨骼肌代谢组的特征。在产前 15 周，将 38 头怀孕的经产荷斯坦奶牛分为 2 组中的 1 组，通过不同的饲养方式达到目标体况和背膘厚（BCS：>3.75 和>1.4cm；NBCS：<3.5 和<1.2cm），直到干奶前-49 天。在干奶期和随后的泌乳期，两组均喂食相同的日粮。整个研究过程中都保持了两组之间在 BCS 和 BFT 方面的差异。使用靶向代谢组学方法（AbsoluteIDQ p180 试剂盒；Biocrates Life Sciences AG，因斯布鲁克，奥地利），在与产犊相关的 d-49、3、21 和 84 时，对骨骼肌（半腱肌）样本进行代谢组学特征描述，该方法允许对来自 6 个不同化合物类别的多达 188 种代谢物进行定量（酰基肉碱、氨基酸、生物胺、甘油磷脂、鞘脂和己糖）。在 d-49 时，HBCS 奶牛肌肉中的瓜氨酸和羟十四碳二烯酰肉碱浓度高于 NBCS 奶牛，但肌肽浓度较低。过度饲养并没有影响任何代谢物在 d3 时在肌肉中的浓度。在 d21 时，HBCS 奶牛肌肉中的苯乙胺和亚油酸肉碱浓度低于 NBCS 奶牛，而溶血磷脂酰胆碱酰基 C20:4 的情况正好相反。在 d84 时，变化显著的代谢物主要是长链（>C32）酰基烷基磷脂酰胆碱和二酰基磷脂酰胆碱，以及 3 种长链（>C16）鞘磷脂，在 HBCS 奶牛中均低于 NBCS 奶牛。这些数据有助于更好地了解奶牛在过渡期骨骼肌的代谢适应，尽管与过度饲养相关的瓜氨酸、羟十四碳二烯酰肉碱、肌肽和苯乙胺的调节的生理意义和潜在分子机制仍不清楚，需要进一步研究。在肌肉溶血磷脂酰胆碱和磷脂酰胆碱浓度观察到的变化可能表明磷脂酰胆碱代谢发生改变，可能导致膜硬度增加，这可能导致过度饲养奶牛肌肉中的胰岛素信号异常。
