USE OF AN ANIMAL-MODEL FOR GENETIC EVALUATION OF THE LACAUNE DAIRY SHEEP

This paper presents the characteristics and the results of an analysis of the Lacaune dairy sheep with an animal model. The analysis involved 1 003 071 lactations of parity 1 to 7, exhibited from 1978 to 1989 by 340 541 Lacaune dairy ewes. After including useful pedigrees, 492 149 females and 8231 males were evaluated for milk yield. Fat and protein yields and contents, partially recorded since 1986, were also analysed. 27 groups were defined for unknown parents only, according to the sex and birth year of their progeny. Results were consistent with those obtained with the present evaluation system (IF2). For males, the correlations between expected breeding values ranged from 0.92 to 0.98, according to the traits and the distribution of the daughters between flocks. The estimated genetic trend for milk yield was found rather insensitive to the heritability value and reached about 0.18 genetic standard deviation per year, i.e. about two thirds of the phenotypic trend and 2.2% of the production level. Some indication is given about the gain in efficiency due to the animal model.