Abstract

Cull dairy cows contribute almost 10% of national beef production in the United States. However, different factors throughout the life of dairy cows affect their weight and overall body condition as well as carcass traits, and consequently affect their market price. Therefore, the objectives of this study were: (1) to assess relationships between price ratio and carcass merit of cull dairy cows sold through several sites of an auction market and (2) to investigate the effect of animal life history events and live weight on sale barn price (BP) and price ratio (as a measure of relative price), as an indicator of carcass merit. Data from 4 dairy operations included 3,602 cull dairy cow records during the period of 2015 to 2019. Life history events data were collected from each dairy operation through Dairy Comp software; live weight and price were obtained periodically from the auction market, and the carcass data were provided by a local packing plant. Cow price in dollars per unit of live weight ($/cwt) and price ratio were the 2 outcome variables used in the analyses. Price ratio was created aiming to remove seasonality effects from BP (BP divided by the national average price for its respective month and year of sale). The association between price ratio and carcass merit traits was investigated using canonical correlation analysis, and the effect of life history events on both BP and price ratio was inferred using a multiple linear regression technique. More than 70% of the cows were culled in the first 3 lactations, with an average live weight of 701.5 kg, carcass weight of 325 kg, and dressing percentage of 46.3%. On average, cull cows were sold at $57.0/cwt during the period considered. The canonical correlation between price ratio and carcass merit traits was 0.76, indicating that price ratio reflected carcass merit of cull cows. Later lactations led to lower BP compared with cows culled during the first 2 lactations. Injury, and leg and feet problems negatively affected BP. Productive variables demonstrated that the greater milk production might lead to lower cow prices. A large variation between farms was also noted. In conclusion, price ratio was a good indicator of carcass merit of cull cows, and life history events significantly affected sale BP and carcass merit of cull cows sold through auction markets.

中文翻译：

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生活史事件对淘汰奶牛胴体品质和价格的影响

摘要

淘汰奶牛占美国全国牛肉产量的近 10%。然而，在奶牛的整个生命周期中，不同的因素会影响它们的体重和整体身体状况以及胴体特性，从而影响它们的市场价格。因此，本研究的目的是：(1) 评估通过拍卖市场的多个站点出售的淘汰奶牛的价格比和胴体价值之间的关系，以及 (2) 调查动物生活史事件和活重对销售谷仓价格 (BP) 和价格比率（作为相对价格的衡量标准），作为胴体品质的指标。来自 4 个乳品厂的数据包括 2015 年至 2019 年期间的 3,602 头淘汰奶牛记录。通过 Dairy Comp 软件从每个乳品厂收集生活史事件数据；活重和价格定期从拍卖市场获得，胴体数据由当地一家包装厂提供。以美元计的每单位活重的奶牛价格 ($/cwt) 和价格比率是分析中使用的 2 个结果变量。创建价格比率的目的是消除 BP 的季节性影响（BP 除以其各自销售月份和年份的全国平均价格）。使用典型相关分析研究价格比和胴体品质特征之间的关联，并使用多元线性回归技术推断生活史事件对血压和价格比的影响。前3个泌乳期淘汰率超过70%，平均活重701.5公斤，胴体重325公斤，屠宰率46.3%。平均而言，淘汰奶牛的售价为 57 美元。0/cwt 在考虑期间。价格比与胴体品质性状之间的典型相关为0.76，表明价格比例反映了淘汰奶牛的胴体品质。与前 2 个泌乳期淘汰的奶牛相比，后期泌乳导致血压降低。受伤、腿部和足部问题对血压产生负面影响。生产变量表明，更高的牛奶产量可能会导致更低的奶牛价格。还注意到农场之间的巨大差异。总之，价格比是衡量淘汰奶牛胴体价值的良好指标，生活史事件显着影响了通过拍卖市场出售的淘汰奶牛的销售BP和胴体价值。与前 2 个泌乳期淘汰的奶牛相比，后期泌乳导致血压降低。受伤、腿部和足部问题对血压产生负面影响。生产变量表明，更高的牛奶产量可能会导致更低的奶牛价格。还注意到农场之间的巨大差异。总之，价格比是衡量淘汰奶牛胴体价值的良好指标，生活史事件显着影响了通过拍卖市场出售的淘汰奶牛的销售BP和胴体价值。与前 2 个泌乳期淘汰的奶牛相比，后期泌乳导致血压降低。受伤、腿部和足部问题对血压产生负面影响。生产变量表明，更高的牛奶产量可能会导致更低的奶牛价格。还注意到农场之间的巨大差异。总之，价格比是衡量淘汰奶牛胴体价值的良好指标，生活史事件显着影响了通过拍卖市场出售的淘汰奶牛的销售BP和胴体价值。