School of Veterinary Medicine and Science, University of Nottingham, Sutton Bonington Campus, Leicestershire LE12 5RD, United Kingdom.
School of Veterinary Medicine and Science, University of Nottingham, Sutton Bonington Campus, Leicestershire LE12 5RD, United Kingdom.
J Dairy Sci. 2023 Jun;106(6):4184-4197. doi: 10.3168/jds.2021-21749. Epub 2023 Apr 5.
Claw horn disruption lesions (CHDL) are a leading cause of lameness in dairy cattle, and the development, effect, and pathology of these lesions remains an open area of interest within dairy cattle health. Current literature typically attempts to measure the effect of risk factors on the development of CHDL over a relatively short time period. Further understanding of the interaction of CHDL and the long-term effect of early CHDL in a cow's life remains an important area of research which is so far mostly unexplored. In this study 57,974 cows from 1,332 herds were selected and their regular claw trimming records containing important claw health information were used to model the long-term effect of lesions in a cow's lifetime in a 6-state multistate model. A multistate model predicts the time before transition from any one state to another and the probability of transition to a future state. The 6 lesion states that were modeled were as follows: never had a lesion, first recorded lesion event, no recorded lesion after first lesion event, second or subsequent recorded lesion event, no recorded lesion after second or subsequent lesion event, and culled. The effect of various cow level covariates on the transition probabilities between various states was tested. For the first time, this study shows the importance and effect of the first lesion and other cow level factors on long-term claw health. Model results showed that the timing and severity of the first recorded lesion event significantly influenced the likelihood of a future lesion being present. Cows with CHDL present within the 180 d of first calving had a short-term increased risk and long-term decreased risk of a future lesion, compared with cows that present with CHDL later than 180 d of first lactation. Moreover, presence of a severe first lesion increased a cow's risk of a future lesion being present. The model was used to evaluate the relative difference between high-risk cows (age of first calving ≥793 d, breeding values in the lowest quartile) and low-risk cows (age of first calving ≤718 d, breeding values in the highest quartile). Our results indicated that these low-risk cows present with a lesion on an average 3 mo later than high-risk cows. Furthermore, results from the model evaluation of a simulated herd with cows with breeding values in the higher quartile indicated that cows present with a CHDL on an average 7.5 mo later compared with a herd where cows have breeding values distributed in a lower quartile.
爪角破坏病变（CHDL）是奶牛跛行的主要原因，这些病变的发展、影响和病理学仍然是奶牛健康领域的一个热点研究领域。目前的文献通常试图在相对较短的时间内测量风险因素对 CHDL 发展的影响。进一步了解 CHDL 与奶牛一生中早期 CHDL 的长期影响仍然是一个重要的研究领域，到目前为止，这方面的研究还很少。在这项研究中，从 1332 个牛群中选择了 57974 头奶牛，利用其定期修剪爪子的记录，其中包含重要的爪子健康信息，使用 6 状态多状态模型对奶牛一生中病变的长期影响进行建模。多状态模型预测从一个状态到另一个状态的时间，以及向未来状态转变的概率。建模的 6 种病变状态如下：从未有过病变、首次记录病变事件、首次病变事件后无记录病变、第二次或随后记录病变事件、第二次或随后病变事件后无记录病变、以及淘汰。测试了各种奶牛水平协变量对各种状态之间转变概率的影响。本研究首次表明了首次病变和其他奶牛水平因素对长期爪子健康的重要性和影响。模型结果表明，首次记录病变事件的时间和严重程度显著影响未来病变存在的可能性。与首次泌乳后 180 天内出现 CHDL 的奶牛相比，首次产犊后 180 天内出现 CHDL 的奶牛在短期内发生未来病变的风险增加，而长期发生未来病变的风险降低。此外，严重的首次病变增加了奶牛未来出现病变的风险。该模型用于评估高风险奶牛（首次产犊年龄≥793 天，育种值处于最低四分位数）和低风险奶牛（首次产犊年龄≤718 天，育种值处于最高四分位数）之间的相对差异。我们的结果表明，这些低风险奶牛的病变平均比高风险奶牛晚出现 3 个月。此外，对一个具有较高四分位值奶牛的模拟牛群的模型评估结果表明，与一个具有较低四分位值奶牛的牛群相比，CHDL 出现在牛群中的平均时间晚了 7.5 个月。
