Department of Animal and Poultry Science, University of Guelph, Guelph, ON N1G 2W0, Canada.
J Anim Sci. 2013 Sep;91(9):4245-55. doi: 10.2527/jas.2013-6421. Epub 2013 Jul 26.
Twenty-two nonlactating multiparous pregnant beef cows (639 ± 68 kg) were used to investigate the effect of dietary restriction on the abundance of selected proteins regulating cellular energy metabolism. Cows were fed at either 85% (n = 11; LOW) or 140% (n = 11; HIGH) of total NE requirements. The diet consisted of a haylage-based total mixed ration containing 20% wheat straw. Cows were slaughtered by block (predicted date of parturition), beginning 83 d after the initiation of dietary treatments and every week thereafter for 6 wk, such that each block was slaughtered at approximately 250 d of gestation. Tissue samples from liver, kidney, sternomandibularis muscle, ruminal papilli (ventral sac), pancreas, and small intestinal muscosa were collected at slaughter and snap frozen in liquid N2. Western blots were conducted to quantify abundance of proliferating cell nuclear antigen (PCNA), ATP synthase, ubiquitin, and Na/K+ ATPase for all tissues; PPARγ, PPARγ coactivator 1 α (PGC-1α), and 5´-adenosine monophosphate-activated protein kinase (AMPK) and the activated form phosphorylated-AMPK (pAMPK) for liver, muscle, and rumen; phosphoenolpyruvate carboxykinase (PEPCK) for liver and kidney; and uncoupling protein 2 (UCP2) for liver. Statistical analysis was conducted using Proc Mixed in SAS and included the fixed effects of dietary treatment, cow age, block, and the random effect of pen. Dietary treatments resulted in cows fed HIGH having greater (P ≤ 0.04) ADG and final BW than cows fed LOW. Abundance of ubiquitin in muscle was greater (P = 0.009) in cows fed LOW, and PCG-1 α in liver was greater (P = 0.03) in cows fed HIGH. Hepatic O2 consumption was greater in HIGH (P ≤ 0.04). Feed intake can influence the abundance of important metabolic proteins and suggest that protein degradation may increase in muscle from moderately nutrient restricted cows and that energy metabolism in liver increases in cows fed above NE requirements.
22 头非泌乳经产妊娠肉牛（639±68kg）用于研究饮食限制对调节细胞能量代谢的选定蛋白质丰度的影响。奶牛分别以 85%（n=11；LOW）或 140%（n=11；HIGH）的总 NE 需要量进行饲养。日粮由基于干草青贮料的全混合日粮组成，含有 20%的小麦秸秆。奶牛通过块（预计分娩日期）屠宰，从开始饲养的第 83 天开始，此后每 1 周屠宰 1 次，共 6 周，使得每个块在妊娠 250d 左右屠宰。屠宰时采集肝脏、肾脏、胸骨舌骨肌、瘤胃乳头（腹囊）、胰腺和小肠黏膜的组织样品，并在液氮中立即冷冻。进行 Western 印迹法，以定量所有组织中的增殖细胞核抗原（PCNA）、三磷酸腺苷合酶、泛素和 Na/K+ATP 酶的丰度；肝脏、肌肉和瘤胃中的过氧化物酶体增殖物激活受体γ（PPARγ）、PPARγ 共激活因子 1α（PGC-1α）和 5´-腺苷单磷酸激活蛋白激酶（AMPK）和磷酸化 AMPK（pAMPK）的激活形式；肝脏和肾脏中的磷酸烯醇丙酮酸羧激酶（PEPCK）；以及肝脏中的解偶联蛋白 2（UCP2）。使用 SAS 中的 Proc Mixed 进行统计分析，包括饮食处理、奶牛年龄、块和围栏的固定效应以及随机效应。饮食处理导致饲喂 HIGH 的奶牛具有更高的 ADG 和最终 BW（P≤0.04）。饲喂 LOW 的奶牛肌肉中泛素的丰度更高（P=0.009），饲喂 HIGH 的奶牛肝脏中 PCG-1α 的丰度更高（P=0.03）。HIGH 组的肝耗氧量更大（P≤0.04）。采食量可以影响重要代谢蛋白质的丰度，并表明中度营养限制的奶牛肌肉中蛋白质降解可能增加，并且饲喂高于 NE 需要量的奶牛肝内能量代谢增加。
