Department of Social Sciences, Business Economics Group, Wageningen University, Wageningen, The Netherlands.
Faculty of Veterinary Medicine, Department of Population Health Sciences, Utrecht University, Utrecht, The Netherlands.
PLoS One. 2022 Dec 27;17(12):e0278204. doi: 10.1371/journal.pone.0278204. eCollection 2022.
The associations between reproductive performance, milk yield and health status with the risk of culling, and thus with a cow's longevity, have been well documented at the individual cow level. Associations at individual cow level may, however, not be valid at herd level due to interrelated herd management aspects and/or policy restrictions. The objective of this study was to explore the association of herd performance indicators with herd-level dairy cow longevity under Dutch production conditions. Longevity was expressed by three different measures, viz. age at culling, lifetime milk production of culled cows and culling rate. The evaluated herd performance indicators included factors on milk production, youngstock rearing, reproduction and health performance as registered on 10 719 Dutch commercial dairy herds during the period 2007-2016. Averaged over herds and the evaluated period, the age of culled milking cows was 2 139 days (5.8 years, SD±298 days), the lifetime milk production of culled cows was 31 238 kg (SD±7,494 kg), and the culling rate was 0.24 (SD±0.08). A mixed linear regression modelling approach was applied to evaluate the association of each of the three longevity measures with the selected herd performance indicators. The results indicated that only four herd performance indictors (herd size, herd expansion, heifer ratio and the proportion of cows with potential subclinical ketosis) shared significant associations with all three longevity variables. Generally, the strength of the associations between each of the evaluated longevity measures and herd performance indicators was only limited. The absence of strong associations between the longevity measures and herd performance indicators reveal that there is potential of extending cattle longevity without affecting the herd performance in terms of milk production, reproduction and health. Moreover, only part of the observed variance in longevity among the herds over time was explained by the herd performance variables, indicating that differences in longevity at herd level may predominantly be determined by other factors, like farmers' attitude and strategic management.
在个体牛水平上，已经有大量文献记录了繁殖性能、产奶量和健康状况与淘汰风险（因此也与牛的寿命）之间的关系。然而，由于 herd 管理方面的相互关联和/或政策限制，个体牛水平上的关联在 herd 水平上可能并不成立。本研究的目的是在荷兰生产条件下，探索 herd 性能指标与 herd 级奶牛寿命之间的关联。寿命通过三种不同的指标来表示，即淘汰时的年龄、淘汰奶牛的终生产奶量和淘汰率。评估的 herd 性能指标包括 milk production、youngstock 饲养、繁殖和健康性能方面的因素，这些因素是在 2007-2016 年期间在 10719 个荷兰商业奶牛 herd 上登记的。在 herd 间和评估期间取平均值，淘汰泌乳奶牛的年龄为 2139 天（5.8 岁，SD±298 天），淘汰奶牛的终生产奶量为 31238 公斤（SD±7494 公斤），淘汰率为 0.24（SD±0.08）。采用混合线性回归模型方法评估了三种寿命指标中的每一种与所选 herd 性能指标的关联。结果表明，只有四个 herd 性能指标（herd 规模、herd 扩张、小母牛比例和潜在亚临床酮病奶牛的比例）与所有三种寿命变量都存在显著关联。一般来说，评估的每一种寿命指标与 herd 性能指标之间的关联强度都很有限。寿命指标与 herd 性能指标之间缺乏强烈关联表明，在不影响 milk production、繁殖和健康 herd 性能的情况下，有可能延长牛的寿命。此外，随着时间的推移， herd 之间的寿命差异只有一部分可以用 herd 性能变量来解释，这表明 herd 水平上的寿命差异主要可能由其他因素决定，如农民的态度和战略管理。
