Genetic evaluation of health traits in Slovak Holstein herds using raw diagnoses data

Dairy cows are commonly affected by diseases which negatively impact the economic efficiency of farm profitability and often result in premature culling. This study evaluated the use of raw veterinary records for genetic analysis of health traits in Slovakia (mastitis, claw diseases, metritis and ketosis) using univariate animal models. The final dataset contained 16,703 lactation records for 8,237 Holstein cows. Available raw veterinary data from 2018 to 2023 included 6,930 cases of mastitis, 2,562 cases of claw diseases, 1,320 cases of metritis and 1,125 cases of ketosis. After applying data filtering procedures, the final veterinary dataset retained 2,570 mastitis, 1,001 claw disease, 839 metritis and 500 ketosis cases. For the analysis, diseases were binary coded (0 healthy/1 ill). In cows during first lactation, the occurrence of specific diseases was associated with a lower number of average lactations: 1.55 for ketosis, 1.94 for mastitis, 2.00 for metritis and 2.09 for claw diseases. Heritability estimates were low, from 0.003 ± 0.003 (metritis, ketosis), 0.020 ± 0.006 (mastitis), to 0.050 ± 0.006 (claw diseases). Genetic correlations between diseases were both positive and negative, ranging from 0.674 ± 0.0003 (mastitis and metritis) to 0.262 ± 0.0032 (metritis and ketosis). Sire RBVs ranged from 99.77 (ketosis) to 139.03 (mastitis), with considerable overlap among sires across diseases. This study provides an estimation of genetic parameters of health traits in Slovak Holstein cattle for the first time and is a foundation for the implementation of health trait evaluations in this population. Integrating health traits into routine genetic evaluations is advisable to improve animal health, longevity and sustainability.