Hindman Megan S, Huedepohl Brian, Dewell Grant A, Brick Troy A, Silva Gustavo S, Engelken Terry J
Veterinary Department of Production Animal Medicine, College of Veterinary Medicine, Iowa State University, Ames, IA 50010, USA.
Veterinary Medical Center, Williamsburg, IA 52361, USA.
Animals (Basel). 2022 Jul 27;12(15):1910. doi: 10.3390/ani12151910.
Developing and raising replacement heifers requires a large capital investment for producers. Therefore, it is imperative to discover traits and management practices to eliminate subfertile heifers prior to breeding and pregnancy determination. In this study, four years of data was analyzed from a centralized beef heifer development yard in the Midwest of the United States. The objective of this study was to analyze various heifer physical characteristics and management practices in order to quantify their impact on pregnancy and date of conception. Logistic regression models were built to investigate risk factors associated with conception to artificial insemination (AI), pregnancy by natural service after AI exposure, and pregnancy in the first 21-days of the breeding season. Age at entry, average daily gain from entry to breeding, pelvic width, and year were associated with AI pregnancy (p < 0.05). On the second model, average daily gain from entry to yearling weight, weight at breeding, weight at pregnancy diagnosis, and age at AI were significantly associated with pregnancy. There were no associations with reproductive tract score with any of the response variables analyzed. These results indicate there are physical measurements that can be used to improve the ability to select and develop heifers for improved reproductive performance.
对于养殖者而言，培育和饲养后备小母牛需要大量的资金投入。因此，必须找出相关性状和管理措施，以便在配种和妊娠诊断前淘汰繁殖力低下的小母牛。本研究分析了美国中西部一个集中化肉牛小母牛培育场的四年数据。本研究的目的是分析各种小母牛的身体特征和管理措施，以量化它们对妊娠和受孕日期的影响。构建了逻辑回归模型，以研究与人工授精（AI）受孕、人工授精后自然交配受孕以及繁殖季节前21天内受孕相关的风险因素。入栏时的年龄、从入栏到配种期间的平均日增重、骨盆宽度和年份与人工授精受孕相关（p < 0.05）。在第二个模型中，从入栏到周岁体重期间的平均日增重、配种时的体重、妊娠诊断时的体重以及人工授精时的年龄与受孕显著相关。所分析的任何反应变量与生殖道评分均无关联。这些结果表明，存在一些身体测量指标可用于提高挑选和培育小母牛以改善繁殖性能的能力。
