Institute of Animal Science, Přátelství 815, 104 00 Prague-Uhříněves, Czech Republic.
J Dairy Sci. 2011 Aug;94(8):4090-9. doi: 10.3168/jds.2010-3684.
Relationships between conformation traits and functional longevity in Holstein cows were evaluated using survival analysis. Functional longevity was defined as the number of days between the first calving and culling; that is, length of productive life. The data set consisted of 116,369 Holstein cows that first calved from 2003 to 2008. All cows used in the analysis were scored for conformation between d 30 and d 210 of their first lactation. The data included 48% censored records. Analyses were done separately for 20 linear descriptive type traits, 6 composite traits, and height at sacrum measured in centimeters. Cox proportional hazard models were fitted to analyze data. The hazard function was described as the product of a baseline hazard function and the time-independent effects of age at first calving and sire (random), and the time-dependent effects of stage of lactation and lactation number, herd, year and season, herd size, and 305-d milk production. The strongest relationship between a composite trait and functional longevity was for dairy form, followed by udder and final score. Among the descriptive type traits, the strongest relationships with longevity were found for body condition score, angularity, traits related to udder attachment, and udder depth. Foot and leg traits showed substantially lower effect on functional longevity, and the effect of foot angle was minimal. Functional longevity declined with decreased body condition score of cows. Cows with deep udders had significantly lower functional survival compared with cows with shallow udders. In addition, weak central ligament was associated with significant reduction of cow longevity. For dairy form and angularity, cows classified as very good were the worst with respect to longevity, whereas cows classified as poor were the best. An intermediate optimum was evident for rear legs rear view and rear legs set (side view), whereas cows with sickled legs had lower longevity than cows with straighter legs.
使用生存分析评估荷斯坦奶牛的体型特征与功能寿命之间的关系。功能寿命定义为首次产犊与淘汰之间的天数；也就是说，生产寿命。数据集包括 2003 年至 2008 年首次产犊的 116369 头荷斯坦奶牛。所有用于分析的奶牛在其第一次泌乳的第 30 天至第 210 天之间对体型特征进行评分。数据包括 48%的删失记录。分别对 20 个线性描述体型特征、6 个综合特征以及厘米为单位的荐骨高度进行了分析。使用 Cox 比例风险模型分析数据。危险函数描述为基线危险函数与首次产犊时的年龄和 sire（随机）的时间独立效应以及泌乳阶段和泌乳次数、牛群、年份和季节、牛群规模和 305 天产奶量的时间相关效应的乘积。综合特征与功能寿命之间的最强关系是产奶形态，其次是乳房和最终评分。在描述体型特征中，与寿命关系最强的是体况评分、角度、与乳房附着相关的特征和乳房深度。脚和腿部特征对功能寿命的影响要低得多，脚角度的影响最小。奶牛体况评分降低会导致功能寿命缩短。深乳房的奶牛与浅乳房的奶牛相比，功能生存能力显著降低。此外，薄弱的中央韧带与奶牛寿命的显著减少有关。对于产奶形态和角度，非常好的奶牛在寿命方面表现最差，而差的奶牛表现最好。后腿后视图和后腿设置（侧视图）处于中间最佳状态，而镰刀腿的奶牛比直腿的奶牛寿命更短。
