Genetic and genomic evaluation of claw health traits in Spanish dairy cattle

The purposes of this study were to implement a routine genetic evaluation of claw health traits and to validate the genomic proofs for six claw disorders: dermatitis (DE), sole ulcer (SU), white line disease (WL), concave dorsal wall (CD), interdigital phlegmon (IP), and interdigital hyperplasia (IH). Claw disorders show moderate to high negative correlations with five feet and legs conformation traits, feet & legs (F&L), rear legs rear view (RLRV), foot angle (FA), locomotion (LOC), and bone quality (BQ), which ranged from 0.23 to -0.90. Including feet and legs type traits in a multi-trait evaluation would be a good option in order to increase the reliability of claw health breeding values. Claw trimming information with 593 137 records of six claw disorders of 221 266 cows, daughters of 8 000 bulls, and recorded in 1 418 Holstein dairy herds by 34 trimmers were used to carry out a genetic evaluation for claw disorders considering two scenarios. The first one, a 6-trait analysis with the claw health traits, and in the second one, the type traits were added to the multi-trait analysis. A total claw health index (ISP) was used to compare the results using sires with at least 20 daughters and 50% of reliability. For genomic prediction, a GBLUP with polygenic effect was applied to estimate genomic breeding values. The 1 317 sires reaching a minimum of 50% in reliability of EBV for total claw health index were used as the reference population was applied to estimate genomic breeding values. The inclusion of feet and legs type traits in the multi-trait genetic evaluation increased the reliabilities for claw disorders EBV of proven sires by 8% to 32%. Regarding genomic validation, the correlations between DRP and DGV ranged from 0.15 to 0.36. The regression coefficients were close to 1, except for DE and IH. To achieve a higher accuracy a larger reference population is needed. Therefore, an international genetic evaluation for claw health would increase the sire’s reference population. At national level, performing a single-step evaluation could lead to slightly higher reliability.