title: Evaluation of bull semen fertility by homologous in vitro fertilization tests.
abstract: In vitro fertilization assays were performed to investigate their validity in evaluating artificial insemination (AI) bull fertility. A total of 1,532 oocytes, collected from ovaries at the abattoir, were subsequently used in a 4 x 6 x 2 factorial design: 4 doses of heparin added into the capacitation and fertilization medium (0; 0.05; 0.1 and 0.2 micrograms/ml), 6 different bulls with known on-field non-return (NR) rates (range: 64.6-75.3%) and 2 different ejaculates for each bull, collected within a approximately 1-month interval. Oocytes were considered fertilized when 2 pronuclei (or more) were seen in the ooplasm. Both the heparin dose and bull exerted a highly significant effect on the in vitro fertilization (IVF) rates which ranged, per oocyte group, from 30-80%; bull x dose of heparin interaction was significant (P less than 0.001). The 0.05 micrograms/ml dose of heparin was optimal for discriminating individual bulls. At that dose, the correlation coefficients between the bulls, NR rates and the IVF rates from each ejaculate (within-bull or the mean of two ejaculates), were highly significant (r = 0.83). The rates of polyspermy were also significantly influenced by bull and heparin dose, but there was no interaction. In conclusion, capacitation and fertilization in a modified Tyrode medium containing 0.05 micrograms/ml of heparin may be a valuable tool for evaluating AI bull fertility.
authors.affiliation: UNCEIA--Services Techniques, Maisons-Alfort, France.
authors.forename: B
authors.initials: B
authors.lastname: Marquant-Le Guienne
authors.forename: P
authors.initials: P
authors.lastname: Humblot
authors.forename: M
authors.initials: M
authors.lastname: Thibier
authors.forename: C
authors.initials: C
authors.lastname: Thibault
mesh_terms: D000818:Animals; D002417:Cattle / Q000502:physiology*; D005298:Fertility; D005307:Fertilization in Vitro / Q000187:drug effects; D006493:Heparin / Q000494:pharmacology; D008297:Male; D012661:Semen / Q000502:physiology*
chemical_list: D006493:Heparin