Genetic parameters for foot and claw disorders in Czech Holstein cattle

<br>Our study investigated the genetic variability ofspecific foot and claw disorders, namely <i>dermatitis digitalis</i>, sole ulcer, and three broader categories (infectious diseases, claw horn lesions, and general claw disorder) inCzech Holstein cows. Wealso examined their genetic relationships with clinical mastitis and key fertility traits. Using both linear and threshold animal models, weconcluded that heritability estimates for foot and claw disorders were consistently higher when employing the threshold model. Asignificant finding was the genetic correlation between sole ulcer and <i>dermatitis digitalis</i>, which ranged from 0.21 (calving to305 days inmilk) to0.53 (calving to90days inmilk). Furthermore, weobserved stronger genetic correlations between clinical mastitis and overall foot and claw disorders, claw horn lesions, and infectious diseases during early lactation (calving to90days inmilk) compared tothe entire lactation period. Within this early lactation phase, the strongest genetic correlation was identified between clinical mastitis and claw horn lesions. Interestingly, our research uncovered aunique genetic link between days open and <i>dermatitis digitalis</i>, suggesting that agenetic predisposition toahigher occurrence of<i>dermatitis digitalis</i> may coincide with shorter days open. These results underscore the importance of implementing distinct genetic selection strategies for infectious claw diseases and claw horn lesions in dairy cows. This distinction is crucial due to their differing genetic correlations with other economically important traits, ultimately contributing to a better understanding of claw health genetics and its application in breeding programs.