Genetic Analysis of Type Traits for the Italian Jersey Breed

Anafi (Associazione Nazionale Allevatori Frisona Italiana) is also in charge of the Italian Jersey cattle genetic evaluations. Since interest about this dairy breed is steadily mounting, (co)variance components for 16 type traits of Italian Jersey cows were estimated, in order to start thinking of how to develop a new and more comprehensive selection index. The canonical transformation, in the frame of a multiple-trait animal model, has been used to cope with the high number of traits contemporarily evaluated. These estimates were necessary to calculate heritabilities and correlations and, through these, the EBVs of bulls and cows by two different models, a singleand a multiple-trait animal model. The results of the two models have eventually been compared, mainly as for differences in reliability: mean reliability increaesed from 0.20 to 0.24 (20%) using a multiple-trait model; these values are higher if calculations are limited to bulls with at least 20 daughters.