Scope and Method of Study. Angus x Hereford cows were used to determine the effects of postpartum weight gain (WG) and treatment with bovine somatotropin (bST) on concentrations of hormones in plasma and calf growth. Cows were assigned to a 2 x 2 factorial: WG, to gain either ≤ 0.4 kg/d or > 0.40 kg/d until d 59 post partum. Cows were injected with bST (250 mg) or saline on d 31 and 45 after calving. Variation in maintenance energy requirement (MR) was determined in nonlactating, pregnant Angus x Hereford cows in feeding trials in each of 3 yr. Cows were classified based on MR as low (> 0.5 SD less than mean, L), moderate (+/- 0.5 SD of mean) or high (> 0.5 SD more than mean, H). Relationships among MR and calf performance, plasma concentrations of IGF-I, T4, glucose, insulin and ruminal temperature were determined in yr 2; description of the proteome and evaluation of protein abundance in Longissimus dorsi (LM) of cows with different MR were evaluated in yr 2 and 3; and the relationship of ruminal temperature with parturition and estrus was evaluated. Proteins from LM were separated separate by 2D-DIGE and abundance was quantified and compared. Rumen boluses were placed in the rumen of the cows to measure ruminal temperature (every 15 min) around parturition and estrus.;Findings and Conclusions. Weight gain influenced plasma concentrations of IGF-I and glucose after treatment of cows with bST. However, treatment did not influence reproduction of the cows. Weight gain and bST treatment of the dam increases calf growth. The greatest differences in MR within year for all cows ranged from 24 to 29%. Birth and weaning weights of calves, postpartum BW and BCS of cows, resumption of luteal activity, plasma concentrations of hormones, and ruminal temperature of cows were not influenced by MR. However, concentrations of IGF-I in plasma were negatively correlated with MR at 2 mo post partum. Protein abundance tended to be greater in H for cofilin-2 compared with L cows. Ruminal temperature decreased 1 d before parturition and increased during estrus. Increase efficiency in the cow-calf segment of the beef industry is feasible. These results, the novel description of the proteome of LM in beef cows and the protocol developed to separate the proteins, provide important information for future research. Weaning heavier calves using similar resources, or weaning similar weight calves using less feed, will improve efficiency of beef cattle production and enhance sustainability of the environment.
展开▼
机译：研究范围和方法。 Angus x Hereford奶牛用于确定产后体重增加（WG）和牛生长激素（bST）处理对血浆和小牛生长激素浓度的影响。母牛被分配到2 x 2阶乘：WG，以达到≤0.4 kg / d或> 0.40 kg / d，直到产后d 59。产犊后第31和45天，向母牛注射bST（250 mg）或生理盐水。在3年的喂养试验中，确定了非泌乳，怀孕的安格斯x赫里福德母牛的维持能量需求（MR）的变化。根据MR将母牛分为低（比均值L低0.5 SD），中（比均值+/- 0.5 SD）或高（比H高出0.5 SD）。在第2年确定MR和小腿性能，IGF-I，T4的血浆浓度，葡萄糖，胰岛素和瘤胃温度之间的关系。在第2年和第3年评估了具有不同MR的奶牛背最长肌（LM）的蛋白质组描述和蛋白质丰度评估；并评估了瘤胃温度与分娩和发情的关系。通过2D-DIGE分离来自LM的蛋白质，并进行定量和比较。将瘤胃大剂量瘤胃放置在母牛的瘤胃上，以测量分娩和发情前后的瘤胃温度（每15分钟）。体重增加影响了bST治疗母牛后血浆IGF-I和葡萄糖浓度。但是，治疗并未影响母牛的繁殖。大坝的增重和bST处理可增加小牛的生长。所有奶牛一年内的MR差异最大，范围为24％至29％。牛对小牛的出生和断奶体重，产后BW和BCS，黄体活动恢复，激素血浆浓度和瘤胃温度没有影响。然而，产后2个月血浆中IGF-I的浓度与MR呈负相关。与L牛相比，cofilin-2的H中蛋白质丰度趋向于更高。分娩前1 d，瘤胃温度降低，发情期间瘤胃温度升高。在牛肉行业的小牛犊领域提高效率是可行的。这些结果，肉牛中LM蛋白质组的新颖描述以及分离蛋白质的开发方案为将来的研究提供了重要信息。使用类似资源的断奶较重的犊牛，或使用较少饲料的断奶类似重量的犊牛，将提高肉牛生产效率并增强环境的可持续性。
展开▼
