Ziegler Robert L, Musgrave Jacki A, Meyer Tanya L, Funston Rick N, Dennis Elliott J, Hanford Kathryn J, MacDonald James C, Mulliniks J Travis
West Central Research and Extension Center, University of Nebraska, North Platte, NE.
University of Nebraska-Lincoln Extension, Thedford, NE.
Transl Anim Sci. 2020 Oct 27;4(4):txaa194. doi: 10.1093/tas/txaa194. eCollection 2020 Oct.
Optimizing beef production system efficiency requires an understanding of genetic potential suitable for a given production environment. Therefore, the objective of this retrospective analysis was to determine the influence of cow body weight (BW) adjusted to a common body condition score (BCS) of 5 at weaning-influenced cow-calf performance and postweaning steer and heifer progeny performance. Data were collected at the Gudmundsen Sandhills Laboratory, Whitman, NE, on crossbred, mature cows ( 1,607) from 2005 to 2017. Cow BCS at calving, prebreeding, and weaning were positively associated ( < 0.01) with greater cow BW. Increasing cow BW was positively associated ( < 0.01) with the percentage of cows that conceived during a 45-d breeding season. For every additional 100-kg increase in cow BW, calf BW increased ( < 0.01) at birth by 2.70 kg and adjusted 205-d weaning BW by 14.76 kg. Calf preweaning average daily gain (ADG) increased ( < 0.01) 0.06 kg/d for every additional 100-kg increase in cow BW. Heifer progeny BW increased ( < 0.01) postweaning with every additional 100-kg increase in dam BW. Dam BW did not influence ( ≥ 0.11) heifer puberty status prior to breeding, overall pregnancy rates, or the percentage of heifers calving in the first 21 d of the calving season. Steer initial feedlot BW increased by 7.20 kg, reimplant BW increased by 10.47 kg, and final BW increased by 10.29 kg ( ≤ 0.01) for every additional 100-kg increase in dam BW. However, steer feedlot ADG was not influenced ( > 0.67) by dam BW. Hot carcass weights of steers were increased ( = 0.01) by 6.48 kg with every additional 100-kg increase in cow BW. In a hypothetical model using the regression coefficients from this study, regardless of pricing method, cow-calf producers maximize the highest amount of profit by selecting smaller cows. Overall, larger-sized cows within this herd and production system of the current study had increased reproductive performance and offspring BW; however, total production output and economic returns would be potentially greater when utilizing smaller-sized cows.
优化牛肉生产系统效率需要了解适合特定生产环境的遗传潜力。因此，这项回顾性分析的目的是确定在断奶时将母牛体重（BW）调整到5的共同体况评分（BCS）对母牛-犊牛性能以及断奶后阉牛和小母牛后代性能的影响。数据于2005年至2017年在位于内布拉斯加州惠特曼的古德蒙森沙丘实验室收集，涉及1607头杂交成熟母牛。产犊时、配种前和断奶时的母牛BCS与更大的母牛BW呈正相关（P<0.01）。母牛BW增加与在45天配种季节受孕的母牛百分比呈正相关（P<0.01）。母牛BW每增加100千克，犊牛出生体重增加（P<0.01）2.70千克，205天断奶体重调整后增加14.76千克。母牛BW每增加100千克，犊牛断奶前平均日增重（ADG）增加（P<0.01）0.06千克/天。小母牛后代断奶后BW随着母牛BW每增加100千克而增加（P<0.01）。母牛BW对配种前小母牛的青春期状态、总体妊娠率或产犊季节前21天内产犊的小母牛百分比没有影响（P≥0.11）。母牛BW每增加100千克，阉牛进入饲养场时的初始体重增加7.20千克，再次植入时的体重增加10.47千克，最终体重增加10.29千克（P≤0.01）。然而，阉牛饲养场ADG不受母牛BW影响（P>0.67）。母牛BW每增加100千克，阉牛的热胴体重增加（P = 0.01）6.48千克。在使用本研究回归系数的假设模型中，无论定价方法如何，母牛-犊牛生产者通过选择较小的母牛可实现最高利润。总体而言，在本研究的牛群和生产系统中，体型较大的母牛繁殖性能和后代BW有所提高；然而，使用体型较小的母牛时，总生产产量和经济回报可能会更高。
