title: Genetic and environmental effects on semen traits in Lacaune and Manech tête rousse AI rams.
abstract: Data from 51,107 and 11,839 ejaculates collected on rams of the "Lacaune" and "Manech tête rousse" breeds, respectively, were analysed to determine environmental and genetic factors affecting semen production traits (ejaculate volume, semen concentration, number of spermatozoa and motility) in young (< or = 1 year) and adult (> or = 2 years) rams. Fixed effects and variance components were estimated using multiple trait animal models within each breed. For all traits, the main environmental effects identified were year, season, number of ejaculations, daily variation, interval from previous to current collection and age. Heritability estimates were moderate for volume, concentration and number of spermatozoa (0.12 to 0.33) and lower for motility (0.02 to 0.14). Genetic correlations between ages differed from 1 for all traits (0.14 to 0.90), indicating that semen characteristics corresponded to different traits in young and adult rams. Genetic and phenotypic correlations among traits within age category were globally similar for the different breeds and categories of animals.
authors.affiliation: Station d'amélioration génétique des animaux, INRA, UR631, BP 52627, 31320 Castanet-Tolosan Cedex, France. Ingrid.David@toulouse.inra.fr
authors.forename: Ingrid
authors.initials: I
authors.lastname: David
authors.forename: Xavier
authors.initials: X
authors.lastname: Druart
authors.forename: Gilles
authors.initials: G
authors.lastname: Lagriffoul
authors.forename: Eduardo
authors.initials: E
authors.lastname: Manfredi
authors.forename: Christèle
authors.initials: C
authors.lastname: Robert-Granié
authors.forename: Loys
authors.initials: L
authors.lastname: Bodin
mesh_terms: D000818:Animals; D004542:Ejaculation / Q000502:physiology; D008297:Male; D012661:Semen / Q000502:physiology*; D012756:Sheep / Q000235:genetics / Q000502:physiology*; D013076:Sperm Count / Q000662:veterinary; D013081:Sperm Motility / Q000502:physiology; D013091:Spermatogenesis / Q000502:physiology*; D013094:Spermatozoa / Q000502:physiology*; D013696:Temperature