Souza A F, Wallace R L, Tomlinson D J, Earleywine T, Socha M T, Drackley J K, Osorio J S
School of Animal Sciences, Virginia Tech, Blacksburg, VA 24061.
Department of Veterinary Clinical Medicine, University of Illinois, Urbana, IL 61801.
JDS Commun. 2024 Jan 15;5(4):356-360. doi: 10.3168/jdsc.2023-0408. eCollection 2024 Jul.
Data are limited on how cow hooves develop early in life and how this will affect susceptibility to lameness and claw disorders later in life. The aim of this study was to characterize individual claw growth and wear in dairy calves. A total of 90 male Holstein calves <1 wk old were enrolled in this completely randomized design experiment and monitored until wk 20 of age. Evaluation of hoof development was conducted by visual inspection, and individual claw measurements were taken with a graduated ruler. Claws were numbered from 1 to 8 to maintain consistent data collection, where front claws were numbered 1 to 4 (left to right) and rear claws were 5 to 8. Lateral claws were numbered 1, 4, 5, and 8, and medial claws were 2, 3, 6, and 7. Measurements included length from the coronary band to the end of the hoof wall and from the coronary band to the groove line, resulting in the variables claw length (CL) and groove length (GL), respectively. Hoof development was evaluated at wk 0, 5, 10, 15, and 20. All evaluations were performed by the same person throughout the study to eliminate variation between observers. Hoof growth and wear were derived from CL and GL measurements and analyzed from wk 0 to 20. Claw length at wk 0 was different across claw positions, and maximal claw length was observed in claws in positions 6 and 7 (i.e., rear medial claws). A similar growth pattern in claw length was observed when evaluated from wk 0 to 20, where a greater claw length was observed in claws 6 and 7 compared with other claws. In contrast to claw length, claw wear at wk 20 was lower in claws 6 and 7 compared with other claws. Compared with rear claws, front claws had greater wear at wk 20, and compared with medial claws, lateral claws had greater wear at wk 20. Factors associated with claw length differences at wk 0 remain to be elucidated, but the fact that this uneven claw length difference was maintained 20 wk after birth is puzzling. The complementary claw length to wear described greater wear in claws 1 and 4 (i.e., front lateral) in young calves, which is translated into lower claw length in the same claws by wk 20 after birth. Future research in postnatal hoof growth should strive to understand the potential biological significance of this effect on lameness resistance and longevity of dairy cows.
关于奶牛蹄在生命早期如何发育以及这将如何影响其后期患跛行和蹄部疾病易感性的数据有限。本研究的目的是描述奶牛犊牛单个蹄爪的生长和磨损情况。总共90头1周龄以下的雄性荷斯坦犊牛被纳入这个完全随机设计的实验，并监测至20周龄。通过目视检查对蹄部发育进行评估，并用刻度直尺对单个蹄爪进行测量。蹄爪从1到8编号以保持数据收集的一致性，其中前蹄爪从1到4编号（从左到右），后蹄爪为5到8号。外侧蹄爪编号为1、4、5和8，内侧蹄爪为2、3、6和7。测量包括从冠状带到蹄壁末端的长度以及从冠状带到沟线的长度，分别得出变量蹄爪长度（CL）和沟长度（GL）。在第0、5、10、15和20周对蹄部发育进行评估。在整个研究过程中，所有评估均由同一人进行，以消除观察者之间的差异。蹄爪生长和磨损由CL和GL测量值得出，并在第0至20周进行分析。第0周时不同位置的蹄爪长度不同，在位置6和7（即后内侧蹄爪）的蹄爪中观察到最大蹄爪长度。从第0周评估到20周时，观察到蹄爪长度有类似的生长模式，与其他蹄爪相比，位置6和7的蹄爪长度更长。与蹄爪长度相反，在第20周时，位置6和7的蹄爪磨损低于其他蹄爪。与后蹄爪相比，前蹄爪在第20周时磨损更大，与内侧蹄爪相比，外侧蹄爪在第20周时磨损更大。与第0周时蹄爪长度差异相关的因素仍有待阐明，但这种出生后20周仍保持的不均匀蹄爪长度差异令人费解。蹄爪长度与磨损的互补关系表明，犊牛中位置1和4（即前外侧）的蹄爪磨损更大，这在出生后20周时转化为相同蹄爪的蹄爪长度更低。未来关于产后蹄部生长的研究应努力了解这种影响对奶牛抗跛行能力和寿命的潜在生物学意义。
