title: Variations in quality of frozen-thawed semen from Swedish Red and White AI sires at 1 and 4 years of age.
abstract: The predictability of semen quality of mature sires from measurements at an early age is not well established. The aim of the present study was to determine age-dependent changes in the quality of bull semen for artificial insemination (AI). Semen was collected and frozen from each of six Swedish Red and White (SRB) dairy AI bulls when they were 1 and 4 years old. Three batches were randomly selected from each bull and age group. From each batch, semen was analysed immediately after thawing [post-thaw (PT), control] as well as after washing/resuspension (W) and after a swim-up procedure (SU). The analyses comprised subjective and computerized (computer-aided sperm analysis, CASA) measurements of motility as well as sperm concentration, morphology and membrane integrity. When semen was analysed, PT, overall sperm motility (CASA), concentration of motile spermatozoa and membrane integrity improved when sires were older. After SU, there was a similar improvement in membrane integrity and concentration of motile spermatozoa, but linear motility decreased. No significant differences between ages were recorded after W-treatment. The above findings indicate that SU is not only superior to W-treatment in differentiating semen quality among bulls but also reveals age-dependent changes. Improved motility and membrane integrity suggest increased viability of spermatozoa at 4 years of age in the SRB sires examined here.
authors.affiliation: Department of Obstetrics and Gynaecology, Faculty of Veterinary Medicine, Swedish University of Agricultural Sciences (SLU), Ullsvägen 14C, Clinical Centre, PO Box 7039, Ultuna SE-750 07, Uppsala, Sweden.
authors.forename: Triin
authors.initials: T
authors.lastname: Hallap
authors.forename: Margareta
authors.initials: M
authors.lastname: Håård
authors.forename: Ulle
authors.initials: U
authors.lastname: Jaakma
authors.forename: Birgitta
authors.initials: B
authors.lastname: Larsson
authors.forename: Heriberto
authors.initials: H
authors.lastname: Rodriguez-Martinez
mesh_terms: D000375:Aging; D000818:Animals; D002417:Cattle; D002462:Cell Membrane; D002470:Cell Survival; D015925:Cryopreservation / Q000662:veterinary*; D014644:Genetic Variation; D007700:Kinetics; D008297:Male; D012662:Semen Preservation / Q000662:veterinary*; D013048:Specimen Handling / Q000379:methods / Q000662:veterinary*; D013076:Sperm Count; D013081:Sperm Motility; D013094:Spermatozoa / Q000002:abnormalities; D013548:Sweden; D013997:Time Factors