title: Association of soybean-based extenders with field fertility of stored ram (Ovis aries) semen: a randomized double-blind parallel group design.
abstract: Two consecutive randomized double-blind field fertility experiments were conducted over a 4-month period and aimed at evaluating the association of two commercial soybean lecithin-based extenders (AndroMed [Minitub, Tiefenbach, Germany] and BioXcell [IMV Technologies, L'Aigle, France]) with pregnancy rates of chilled-stored (CS) and frozen-thawed (FT) ram semen. Semen samples with more than 2 × 10(9) sperm per mL and 70% progressive motile spermatozoa were collected via an artificial vagina from twelve proven fertile Chios rams, split-diluted with the above mentioned extenders, packaged in 0.25 mL straws and either stored at 5 ± 1 °C for 30 to 36 hours or frozen and thawed. Non-lactating multiparous ewes were inseminated in progestagen-synchronized estrus either with CS (AndroMed: N = 212 and BioXcell: N = 206; intracervical AI) or with FT (AndroMed: N = 114 and BioXcell: N = 92; laparoscopic intrauterine AI) semen. Ovulation was confirmed in all ewes based on determination of blood plasma progesterone (>1 ng/mL) 8 days post AI. Ewes were screened for pregnancy diagnosis by transabdominal ultrasonography 65 days post AI. BioXcell was superior to AndroMed in preserving the fertilizing potential of CS (P < 0.05) and FT (P < 0.005) semen. In AndroMed-stored semen, young rams (1.5-2.5 years old, N = 8) had a pregnancy rate (59.1%; 124/210) lower than that (72.4%; 84/116) of mature rams (4.5 to 5.5 years, N = 4; P < 0.025). Compared with AndroMed extender, processing of young ram semen in BioXcell extender improved pregnancy rates of CS (66.7%; 88/132 vs. 83.9%; 94/112; P < 0.005) and FT (46.2%; 36/78 vs. 71.0%; 44/62; P < 0.01) spermatozoa. Both extenders were similarly effective in preserving pregnancy rates of mature ram semen (P > 0.05). Ram-by-extender interactions were significant for pregnancy rates of CS and FT semen. Irrespective of extenders, overall pregnancy rates after intracervical and intrauterine AI were 75.1% and 62.2%, respectively (P < 0.001). In conclusion, BioXcell is a suitable extender for short- and long-term storage of ram semen. Selection of the ewes, farms, and extenders for intracervical AI programs can contribute to satisfactory fertility rates with semen preserved more than 24 hours at 5 °C.
authors.affiliation: EquiBiotech Inc-Research Services in Farm Animal Breeding, Thessaloniki, Greece. drtarekkhalifa@gmail.com
authors.forename: Tarek
authors.initials: T
authors.lastname: Khalifa
authors.forename: Aristotelis
authors.initials: A
authors.lastname: Lymberopoulos
authors.forename: Ekaterini
authors.initials: E
authors.lastname: Theodosiadou
mesh_terms: D000818:Animals; D003080:Cold Temperature; D015925:Cryopreservation / Q000379:methods / Q000662:veterinary; D003451:Cryoprotective Agents; D004311:Double-Blind Method; D004973:Estrus Synchronization; D005260:Female; D005298:Fertility; D007315:Insemination, Artificial / Q000662:veterinary; D054709:Lecithins; D008297:Male; D011247:Pregnancy; D018873:Pregnancy Rate; D012662:Semen Preservation / Q000379:methods / Q000662:veterinary*; D034561:Sheep, Domestic; D013025:Glycine max; D013094:Spermatozoa / Q000502:physiology
chemical_list: D003451:Cryoprotective Agents; D054709:Lecithins