title: In vitro sperm penetration speed and its relationship with in vivo bull fertility.
abstract: The in vitro tests utilized to evaluate sperm quality represent an interesting and important approach to evaluate ejaculated fecundant capacity. In the present work, the oocyte-penetrating ability of sperm from two bulls with low and two with high in vivo fertility rate was investigated. Sperm-quality parameters, such as sperm concentration, total and progressive motility, acrosome and total sperm anomalies, proximal cytoplasmic drops and live : dead sperm ratio were assessed and batches of sperm homologues in these parameters were selected. In expt 1, a sperm : oocyte ratio of 3000 was used and the oocytes were fixed 5, 10, 15 and 18 h post-insemination (hpi). In expt 2, the sperm : oocyte ratio was reduced to 1000 and the eggs were fixed at 8 and 10 hpi. The results, analysed by chi-square test, showed significant differences (p <0.001) among bulls at 15 hpi in expt 1 and 8 hpi in expt 2; nevertheless, no accordance was found between sperm penetration rate and in vivo fertility. At 18 hpi, the low-fertility bulls exceeded the two high-fertility bulls, supporting previous reports that suggest an opposite correlation between in vivo and in vitro fertility rate at low doses of heparin. Furthermore, a more efficient zona binding ability of one high-fertility bull was pointed out in expt 2 after the reduction of sperm : oocyte ratio, as it reached the highest percentage of penetration when compared with all the others.
authors.affiliation: Istituto Sperimentale Italiano "Lazzaro Spallanzani", Rivolta d'Adda (CR), Italy. isils@tin.it
authors.forename: R
authors.initials: R
authors.lastname: Puglisi
authors.forename: D
authors.initials: D
authors.lastname: Balduzzi
authors.forename: A
authors.initials: A
authors.lastname: Galli
mesh_terms: D000177:Acrosome / Q000648:ultrastructure; D000818:Animals; D002417:Cattle / Q000502:physiology*; D005260:Female; D005298:Fertility / Q000502:physiology*; D005307:Fertilization in Vitro / Q000662:veterinary; D008297:Male; D013076:Sperm Count; D013081:Sperm Motility; D013084:Sperm-Ovum Interactions / Q000502:physiology*; D013094:Spermatozoa / Q000648:ultrastructure