Multiple-trait genetic parameters and genetic evaluation of udder-type traits in Lacaune dairy ewes

Genetic parameters for three linear udder-type traits (teat angle, udder cleft and udder depth) in the Lacaune breed were estimated by restricted maximum likelihood (REML) using a multiple-trait animal model. The analyses were carried out on 82,019 primiparous ewes in 352 flocks, recorded by 12 classifiers from 2000 to 2003. Estimated breeding values (EBV) were computed for udder-type traits and correlations between EBV for udder-type traits, EBV for milk yield and somatic cell scores were examined. Heritability estimates were 0.19 for udder depth, 0.26 for udder cleft and 0.33 for teat angle. The genetic correlations among udder traits were globally moderate to high (ranging from 0.14 to 0.49) and always favourable. Over the last 5 years, the trends of EBV showed a deterioration of udder-type traits, especially for udder depth. Most correlations between EBV for type traits and EBV for milk traits were weak. The correlations of the combined index with udder cleft and teat angle were close to zero while that of udder depth with the former was − 0.29, confirming the EBV trends. In addition, the correlations between EBV for somatic cell scores and EBV for udder-type traits were weak but favourable (from 0.1 to 0.2).