Development of an animal-based global welfare score usable in dairy cattle breeding.

Evaluation of welfare in dairy cattle is a challenge especially at the animal-based level. The objectives of this study were thus to develop an animal-based welfare score but also to evaluate its possible use in selection for welfare. The Welfare Quality Assessment Protocol (WQP) for cattle is currently considered a reference for welfare but only provides a score for the farm. A total of 2702 dairy cows were assessed for at least one animal-based measure of the WQP in 28 Walloon farms with a mean of 2.54 audits by farm and a maximum of 5. To develop this animal-based welfare indicator, a maximum of individual measures was used and combined with farm level indicators. Indeed, some welfare criteria were the same for the whole herd and could not be individualized (e.g., availability of water). To optimize this indicator, animal-based measures were selected based on 4 criteria: (a) if available, at least one measure was kept by welfare criteria described in the WQP to stay in line with the welfare principles; (b) the more representative measures based on genetic correlations among them were prioritized to indirectly select for the non-chosen measures; (c) measures with relevant genetic correlation with production traits (milk production, fat percentage, protein percentage, somatic cell count) were preferred to allow the concomitant selection for this indicator and for high production traits and low somatic cell count; (d) measures with a high heritability allowed to maximize heritability of the final indicator and thus to allow selection for welfare. On this basis, the individual measures selected were body condition score, udder cleanliness, number of lesions, lameness score, respiratory score, diarrhea score and avoidance distance. The final score obtained by combining these individual measures with farm level measures presented a positive genetic correlation with protein percentage (0.18 ± 0.14), a negative genetic correlation with somatic cell count (−0.14 ± 0.23) and a heritability of 0.25 ± 0.08. In conclusion, this study allowed the development of a first promising animal-based welfare score and showed that selection for welfare seems possible.