# Growth and wear characteristics of individual claws in young dairy calves

## TL;DR

This study tracks how dairy calves' hooves grow and wear from birth to 20 weeks, finding rear medial claws are longer and experience less wear.

## Contribution

The study provides new empirical data on early-life hoof development patterns in dairy calves, particularly the persistent length and wear differences in rear medial claws.

## Key findings

- Rear medial claws (6 and 7) were longest at birth and remained so until 20 weeks.
- Front claws and lateral claws experienced more wear than rear and medial claws by week 20.
- Claws 1 and 4 (front lateral) showed increased wear, leading to reduced length by week 20.

## Abstract

Summary: The objective of this study was to characterize individual claw growth and wear in dairy calves. We tracked hoof development in 90 male Holstein calves from 1 to 20 weeks of age. Hoof development was evaluated through visual inspection, and individual claw measurements were recorded using a graduated ruler. At week 0, we observed differences in claw length across different positions, with the rear medial claws (claws 6 and 7) being the longest. This elongation of the rear medial claws persisted until 20 weeks of age. Interestingly, claw wear at week 20 was lower in the rear medial claws compared with other claws. Front claws experienced more wear than rear claws, and lateral claws exhibited greater wear than medial claws. Furthermore, claws 1 and 4 (front lateral) showed increased wear, leading to reduced claw length by week 20. The factors contributing to the observed claw length differences at week 0 remain to be determined.

Summary: The objective of this study was to characterize individual claw growth and wear in dairy calves. We tracked hoof development in 90 male Holstein calves from 1 to 20 weeks of age. Hoof development was evaluated through visual inspection, and individual claw measurements were recorded using a graduated ruler. At week 0, we observed differences in claw length across different positions, with the rear medial claws (claws 6 and 7) being the longest. This elongation of the rear medial claws persisted until 20 weeks of age. Interestingly, claw wear at week 20 was lower in the rear medial claws compared with other claws. Front claws experienced more wear than rear claws, and lateral claws exhibited greater wear than medial claws. Furthermore, claws 1 and 4 (front lateral) showed increased wear, leading to reduced claw length by week 20. The factors contributing to the observed claw length differences at week 0 remain to be determined.

•Claw length at week 0 differed across claw positions, with the maximal claw length observed in claws in positions 6 and 7.•Claw length evaluated until 20 weeks of age revealed that a greater claw length was maintained in claws 6 and 7 compared with other claws.•Claw wear at 20 weeks of age was lower in claws 6 and 7 compared with other claws.•At 20 weeks of age, front claws had greater wear than rear claws, and lateral claws had greater wear than medial claws.•Factors associated with claw length differences at week 0 remain to be elucidated, but it is puzzling that this uneven claw length difference was maintained 20 weeks after birth.

Claw length at week 0 differed across claw positions, with the maximal claw length observed in claws in positions 6 and 7.

Claw length evaluated until 20 weeks of age revealed that a greater claw length was maintained in claws 6 and 7 compared with other claws.

Claw wear at 20 weeks of age was lower in claws 6 and 7 compared with other claws.

At 20 weeks of age, front claws had greater wear than rear claws, and lateral claws had greater wear than medial claws.

Factors associated with claw length differences at week 0 remain to be elucidated, but it is puzzling that this uneven claw length difference was maintained 20 weeks after birth.

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.