Goat milk somatic cell counts have been collected for several years in France by the national milk recording organization. Information is used for health management, because repeatedly elevated somatic cell counts are a good indirect predictor of intramammary infection. Genetic parameters were estimated for 67,882 and 49,709 primiparous goats of the dairy Alpine and Saanen breeds, respectively, with complete information for milk somatic cell counts and milk production traits. About 40% of the goats had additional information for 11 udder type traits scored by official classifiers of the breeders' association CAPGENES. Estimates were obtained by REML with an animal model. The studied trait was lactation somatic cell score (LSCS), the weighted mean of somatic cell score (log-transformed SCC) adjusted for lactation stage. Heritability of LSCS was 0.20 and 0.24 in the Alpine and Saanen breeds, respectively. Relationships with milk production and udder type traits were additionally estimated by using multitrait analyses. Heritability estimates in first lactation ranged from 0.30 to 0.35 for lactation milk, fat, and protein yields; from 0.60 to 0.67 for fat and protein contents; and from 0.22 to 0.50 for udder type traits. Genetic correlations of somatic cell score with milk production traits were generally low, ranging from -0.13 to 0.12. Slightly more negative correlations were estimated for fat content: -0.18 and -0.20 in Saanen and Alpine breeds, respectively. Lactation somatic cell score was genetically correlated with udder floor position (r(g)=-0.24 and -0.19 in the Alpine and Saanen breeds, respectively), and, in Saanen, teat length, teat width, and teat form (r(g)=0.29, 0.34 and -0.27, respectively). These results suggest that a reduction in somatic cell count can be achieved by selection while still improving milk production and udder type and teat traits.

No abstract

No abstract

Summary — Genetic parameters for dairy traits in first lactation (milk yield, fat and protein yields, fat and protein contents) were estimated by restricted maximum likelihood in the Alpine and Saanen goat breeds from records including progeny of 473 and 238 unproven bucks respectively, mainly used in natural mating. The differences between breeds could also be estimated when the flocks used both breeds. The sampling of the data sets, the addition of data from 28 and 22 progenies of Al proven sires, and the relationship matrix between sampling sires contributed to increase the connection level between flocks, which, however, remained rather low. In the same environmental conditions, particularly in the same year-flock, the Saanen breed appeared more high-yielding than the Alpine, but solid content was lower. Within-breed, the genetic standard deviation was 1.8-2 fold larger for fat content than for protein content. The heritability of fat and protein yields was rather high (0.31 to 0.39). The genetic correlations between yields were larger than 0.8. They were generally negative but rather low (-0.30 (0,3i -0,39

No abstract

Reproductive seasonality observed in all breeds of goats originating from temperate latitudes and in some breeds from subtropical latitudes can now be controlled by artificial changes in photoperiod. Short days stimulate sexual activity, while long days inhibit it. This knowledge has allowed the development of photoperiodic treatments to control sexual activity in goats, for both the buck and doe. In the French intensive milk production system, goat AI plays an important role to control reproduction and, in conjunction with progeny testing, to improve milk production. Most dairy goats are inseminated out of the breeding season with deep frozen semen, after induction of oestrus and ovulation by hormonal treatments. This protocol provides a kidding rate of approximately 65%. New breeding strategies have been developed, based on the buck effect associated with AI, to reduce the use of hormones. With the development of insemination with frozen semen, a classical selection programme was set up, including planned mating, progeny testing and the diffusion of proved sires by inseminations in herds. Functional traits have become important for efficient breeding schemes in the dairy goat industries. Based on knowledge gained over the past decade, the emphasis in selective breeding has been placed on functional traits related to udder morphology and health. New windows have been opened based on new molecular tools, allowing the detection and mapping of genes of economic importance.

Summary — Genetic parameters for dairy traits in first lactation (milk yield, fat and protein yields, fat and protein contents) were estimated by restricted maximum likelihood in the Alpine and Saanen goat breeds from records including progeny of 473 and 238 unproven bucks respectively, mainly used in natural mating. The differences between breeds could also be estimated when the flocks used both breeds. The sampling of the data sets, the addition of data from 28 and 22 progenies of Al proven sires, and the relationship matrix between sampling sires contributed to increase the connection level between flocks, which, however, remained rather low. In the same environmental conditions, particularly in the same year-flock, the Saanen breed appeared more high-yielding than the Alpine, but solid content was lower. Within-breed, the genetic standard deviation was 1.8-2 fold larger for fat content than for protein content. The heritability of fat and protein yields was rather high (0.31 to 0.39). The genetic correlations between yields were larger than 0.8. They were generally negative but rather low (-0.30 (0,3i -0,39

-Les effets sur les performances laitières des 5 principaux allèles du locus de la caséine ocg l caprine, oc51-Cn'!'°B!C,E,F (appelés respectivement A, B, C, E, F), qui contrôlent le polymorphisme à effet quantitatif de cette lactoprotéine, ont été analysés dans la descendance de 5 boucs hétérozygotes de race Alpine. Ce polymorphisme n'a pas d'effets sur la quantité de lait. Par rapport à l'allèle «faible» (F), les allèles «forts» A et C ont, en revanche, un effet significatif sur le taux de protéines vraies (+2,5, +2,6 et 1,8 g/kg pour les 3 familles étudiées), le taux butyreux (+1,5, +2,2 et +1,1 g/kg) et la quantité de matière protéique vraie (+2,3, +2,0 et +1,5 kg). Par rapport à l'allèle «moyen» (E), l'allèle fort A a un effet significatif sur le taux de protéines vraies (+2,0 g/kg) et le taux butyreux (+2,6 g/kg). Les résultats obtenus sur le taux de protéines vraies sont en accord avec les estimations antérieures des effets de ces allèles sur le taux de caséine. chèvre / polymorphisme génétique / caséine mi / production laitière Summary-Effects of the mi"casein polymorphism on goat dairy performances: a within-sire analysis of alpine bucks. The effects of the main alleles at the goat o 's icasein locus (a,,_Cn A , B , C , E , F called A, B, C, E, F) on milk production traits were estimated via a within-sire analysis of the progeny of 5 Alpine bucks. This polymorphism had no effect on milk yield. On the other hand, compared with the weak F allele, the strong alleles A and C had a significant effect on the true protein content (+,!.5, +2.6 and +1.8 g/kg for 3 families), the fat content (+1.5, +2.2 and +1.1 g/kg) and the true protein yield (+2.3, +2.0 and +1.5 kg). Compared with the intermediate E allele, the strong A allele had a significant effect on the true protein content (+2.0 g/kg) and the fat content (+2.6 g/kg). The results on the true protein content were in agreement with previous estimates of the effects of the same alleles on the casein content of milk. goat / genetic polymorphism / 1X s1 casein / milk production