title: Sperm concentration at freezing affects post-thaw quality and fertility of ram semen.
abstract: We have investigated the effect of sperm concentration in the freezing doses 200, 400, 800, and 1600 × 10(6) mL(-1) on the post-thaw quality and fertility of ram semen. Semen was collected from seven adult Churra rams by artificial vagina during the breeding season. The semen was diluted in an extender (TES-Tris-fructose, 20% egg yolk, and 4% glycerol), to a final concentration of 200, 400, 800, or 1600 × 10(6) mL(-1) and frozen. Doses were analyzed post-thawing for motility (computer-assisted sperm analysis system [CASA]), viability, and acrosomal status (fluorescence probes propidium iodide [PI]/peanut agglutinin conjugated with fluorescein thiocyanate (PNA-FITC), SYBR-14/PI [Invitrogen; Barcelona, Spain] and YO-PRO-1/PI [Invitrogen; Barcelona, Spain]). Total motility and velocity were lower for 1600 × 10(6) mL(-1) doses, while progressive motility and viability were lower both for 800 and 1600 × 10(6) mL(-1). The proportion of viable spermatozoa showing increased membrane permeability (YO-PRO-1+) rose in 800 and 1200 × 10(6) mL(-1). Intrauterine inseminations were performed with the 200, 400, and 800 × 10(6) mL(-1) doses at a fixed sperm number (25 × 10(6) per uterine horn) in synchronized ewes. Fertility (lambing rate) was similar for semen frozen at 200 (57.5%) or 400 × 10(6) mL(-1) (54.4%), whereas it was significantly lower for 800 × 10(6) mL(-1) (45.5%). In conclusion, increasing sperm concentration in cryopreserved semen, at least at 800 × 10(6) mL(-1) and more, adversely affects the postthawing quality and fertility of ram semen.
authors.affiliation: ITRA-ULE, INDEGSAL, University of León, León, Spain.
authors.forename: M
authors.initials: M
authors.lastname: Alvarez
authors.forename: J
authors.initials: J
authors.lastname: Tamayo-Canul
authors.forename: E
authors.initials: E
authors.lastname: Anel
authors.forename: J C
authors.initials: JC
authors.lastname: Boixo
authors.forename: M
authors.initials: M
authors.lastname: Mata-Campuzano
authors.forename: F
authors.initials: F
authors.lastname: Martinez-Pastor
authors.forename: L
authors.initials: L
authors.lastname: Anel
authors.forename: P
authors.initials: P
authors.lastname: de Paz
mesh_terms: D000818:Animals; D015925:Cryopreservation / Q000662:veterinary*; D005298:Fertility; D005615:Freezing; D008297:Male; D055101:Semen Analysis / Q000662:veterinary*; D012756:Sheep; D013081:Sperm Motility; D013094:Spermatozoa / Q000502:physiology*