School of Veterinary Medicine and Science, University of Nottingham, Sutton Bonington Campus, Leicestershire, United Kingdom, LE12 5RD.
Sir Peter Mansfield Imaging Centre, University of Nottingham, University Park Campus, Nottingham, United Kingdom, NG7 2RD.
J Dairy Sci. 2021 Jun;104(6):7026-7038. doi: 10.3168/jds.2020-19843. Epub 2021 Mar 25.
Claw horn lesions (CHL) are the result of a failing of the functional anatomy of the hoof in dairy cows. The digital cushion is understood to be a vital structure in the prevention of CHL. Claw horn lesions have previously been shown to lead to pathological change to the pedal bone; however, their effects on the digital cushion are unknown. The primary aim of this study was to examine associations between the history of CHL through an animal's life and the structure of the digital cushion at slaughter using magnetic resonance imaging. The retrospective cohort study resulted in the scanning of 102 pairs of hindfeet, collected from adult Holstein dairy cows culled from a research herd, using a 3-Tesla research-grade magnetic resonance imaging scanner. Volume and fat measurements were calculated for each digital cushion within each claw from a modified Dixon Quant sequence. Animal-level variables were constructed around the animals' lactating lifetime, with lameness scores and body condition score collected at least every 2 wk. The combined volume of digital cushion in the lateral claws was used as the outcome variable in multivariable linear models. The volume of the digital cushion was negatively associated with the number of lameness events or CHL recorded. Furthermore, animals with body condition score >3, culled later in lactation, or of a greater body weight were more likely to have a higher volume of digital cushion in the lateral claws. We propose that the observations made in the current study are the effects of a range of factors broadly associated with genetic, developmental, and disease-related inputs. Our understanding of how we can select for genetically more robust animals and how we can precondition the hoof before first calving needs to be improved to reduce the risk of future CHL in adult dairy cattle. Furthermore, understanding optimal treatment regimens and their effect on hoof anatomy may reduce the recurrence of CHL in the current lactation and future lactations.
爪角病变 (CHL) 是奶牛蹄功能解剖失败的结果。数字垫被认为是预防 CHL 的重要结构。先前已经表明，爪角病变会导致跖骨发生病理性变化；然而，它们对数字垫的影响尚不清楚。本研究的主要目的是使用磁共振成像检查动物一生中 CHL 病史与屠宰时数字垫结构之间的关联。这项回顾性队列研究对来自研究牛群淘汰的成年荷斯坦奶牛的 102 对后脚进行了扫描，使用 3T 研究级磁共振成像扫描仪。从改良的 Dixon Quant 序列中计算了每个爪子内每个数字垫的体积和脂肪测量值。动物水平的变量是围绕动物的泌乳寿命构建的，至少每 2 周收集跛行评分和体况评分。将外侧爪的数字垫的总合体积用作多变量线性模型中的结果变量。数字垫的体积与记录的跛行事件或 CHL 的数量呈负相关。此外，体况评分 >3、泌乳后期淘汰或体重较大的动物，其外侧爪的数字垫体积更大的可能性更高。我们提出，当前研究中观察到的现象是与遗传、发育和疾病相关因素广泛相关的一系列因素的影响。我们需要更好地了解如何选择遗传上更健壮的动物，以及如何在首次产犊前对蹄进行预处理，以降低成年奶牛未来 CHL 的风险。此外，了解最佳治疗方案及其对蹄解剖结构的影响可能会减少当前泌乳期和未来泌乳期 CHL 的复发。
