Veterinary Physiology, Vetsuisse Faculty, University of Bern, Bern, Switzerland.
J Dairy Sci. 2010 Nov;93(11):5200-15. doi: 10.3168/jds.2010-3265.
Metabolic and endocrine adaptations to support milk production during the transition period vary between individual cows. This variation between cows to adapt to lactation may have a genetic basis. The present field study was carried out to determine hepatic adaptations occurring from late pregnancy through early lactation by measuring mRNA abundance of candidate genes in dairy cows on-farm. Additionally, the objective was to observe the diversity in inter-individual variation for the candidate genes that may give indications where individual adaptations at a molecular level can be found. This study was carried out on-farm including 232 dairy cows (parity >3) from 64 farms in Switzerland. Blood and liver samples were collected on d 20±7 before parturition, on d 24±2, and on d 89±4 after parturition. Blood plasma was assayed for concentrations of glucose, nonesterified fatty acids, β-hydroxybutyrate, cholesterol, triglycerides, urea, albumin, protein, insulin, insulin-like growth factor-1, leptin, 3,5,3'-triiodothyronine, and thyroxine. Liver samples were obtained at the same time points and were measured for mRNA abundance of 26 candidate genes encoding enzymes and nuclear receptors involved in gluconeogenesis, fatty acid β-oxidation, fatty acid and triglyceride synthesis, ketogenesis, citric acid cycle, cholesterol synthesis, and the urea cycle. The cows in the present study experienced a marked metabolic load in early lactation, as presented by changes in plasma metabolites and hormones, and responded accordingly with upregulation and downregulation of almost all candidate genes involved in metabolic processes in the liver. The observed inter-individual variation for the candidate genes, which was highest for acetyl-CoA-carboxylase and glycerol-3-phosphate dehydrogenase 2, should be further investigated to unravel the regulation at molecular level for optimal adaptive performance in dairy cows.
在过渡时期，个体奶牛之间支持产奶的代谢和内分泌适应存在差异。奶牛适应泌乳的这种差异可能具有遗传基础。本现场研究旨在通过测量农场奶牛在妊娠后期至泌乳早期的候选基因的 mRNA 丰度，确定肝脏的适应变化。此外，本研究的目的是观察候选基因个体间变异的多样性，这些变异可能表明个体在分子水平上的适应情况。本研究在瑞士的 64 个农场共包括 232 头奶牛（胎次>3）。在分娩前 20±7 天（d）、分娩后第 24±2 天（d）和第 89±4 天（d）采集血样和肝脏样本。采集血样测定血糖、非酯化脂肪酸、β-羟丁酸、胆固醇、甘油三酯、尿素、白蛋白、蛋白、胰岛素、胰岛素样生长因子-1、瘦素、3,5,3'-三碘甲状腺原氨酸和甲状腺素的浓度。在相同时间点采集肝脏样本，测定参与糖异生、脂肪酸β-氧化、脂肪酸和甘油三酯合成、酮体生成、柠檬酸循环、胆固醇合成和尿素循环的 26 个候选基因编码酶和核受体的 mRNA 丰度。本研究中的奶牛在泌乳早期经历了明显的代谢负荷，表现为血浆代谢物和激素的变化，并相应地对几乎所有参与肝脏代谢过程的候选基因进行了上调和下调。候选基因的个体间变异很大，其中乙酰辅酶 A 羧化酶和甘油-3-磷酸脱氢酶 2 的变异最大，应该进一步研究，以揭示分子水平的调控，从而使奶牛具有最佳的适应性能。
