title: Sperm fertility and viability following 48h of refrigeration: evaluation of different extenders for the preservation of bull semen in liquid state.
abstract: Two experiments were conducted to compare the effectiveness of different extenders conventionally used for semen cryopreservation to maintain the viability and fertility of cooled bull semen. In Experiment 1, sperm samples obtained from 20 Nellore bulls were preserved at 5°C for 48h using two extenders containing 20% of egg yolk [Tris (TRIS-R) and Botu-Bov(®) (BB)] and another composed of 1% soy lecithin [Botu-Bov(®)-Lecithin (BB-L)] as substitutes for animal origin products. The samples were evaluated at 6, 24 and 48h for plasma and acrosomal membrane integrity, quantification of thiobarbituric acid reactive substances (ng of TBARS/10(8) cells) and sperm motility parameters by computer-assisted semen analysis (CASA). In Experiment 2, pregnancy rate (P/AI) of 973 fixed-time artificially inseminated Nellore cows were compared when cows were inseminated with conventionally cryopreserved semen in TRIS-egg yolk glycerol (TRIS-C Control, n=253) or semen cooled for 48h in TRIS-R (n=233), BB (n=247) or BB-L (n=240). Although none of the extenders used was effective on maintaining total progressive motility and cellular integrity throughout the 48-h of the refrigeration period (P<0.01), BB-L conferred greater protection against oxidative stress (P<0.05) than egg yolk-based medias. The P/AI for semen samples preserved in TRIS-C, TRIS-R, BB and BB-L were 39.92(a), 25.32(b), 26.32(b) and 33.33(ab), respectively. These results demonstrate that the three conventional extenders used for semen cryopreservation do not provide the protection required to maintain bull semen fertility under refrigeration for a 48-h period, resulting in reduced pregnancy rates. However, the use of lecithin-based medium instead of egg yolk results in greater protection against lipid peroxidation, producing P/AI results comparable to those obtained using frozen semen.
authors.affiliation: School of Veterinary Medicine, Santo Amaro University, UNISA, São Paulo, Brazil. Electronic address: andremacc@yahoo.com.br.
authors.forename: A M
authors.initials: AM
authors.lastname: Crespilho
authors.affiliation: Department of Animal Reproduction, São Paulo University, USP, São Paulo, Brazil.
authors.forename: M
authors.initials: M
authors.lastname: Nichi
authors.affiliation: Department of Animal Reproduction and Veterinary Radiology, São Paulo State University, UNESP, Botucatu, Brazil.
authors.forename: P N
authors.initials: PN
authors.lastname: Guasti
authors.affiliation: Department of Animal Reproduction and Veterinary Radiology, São Paulo State University, UNESP, Botucatu, Brazil.
authors.forename: C P
authors.initials: CP
authors.lastname: Freitas-Dell'Aqua
authors.affiliation: Department of Animal Reproduction, São Paulo University, USP, São Paulo, Brazil.
authors.forename: M F
authors.initials: MF
authors.lastname: Sá Filho
authors.affiliation: Department of Animal Reproduction and Veterinary Radiology, São Paulo State University, UNESP, Botucatu, Brazil.
authors.forename: R R
authors.initials: RR
authors.lastname: Maziero
authors.affiliation: Department of Animal Reproduction and Veterinary Radiology, São Paulo State University, UNESP, Botucatu, Brazil.
authors.forename: J A
authors.initials: JA
authors.lastname: Dell'aqua
authors.affiliation: Department of Animal Reproduction and Veterinary Radiology, São Paulo State University, UNESP, Botucatu, Brazil.
authors.forename: F O
authors.initials: FO
authors.lastname: Papa
mesh_terms: D000818:Animals; D002417:Cattle; D019343:Citric Acid / Q000737:chemistry; D003451:Cryoprotective Agents / Q000494:pharmacology*; D004530:Egg Yolk / Q000737:chemistry; D004973:Estrus Synchronization / Q000379:methods; D005260:Female; D005632:Fructose / Q000737:chemistry; D054709:Lecithins / Q000737:chemistry; D008297:Male; D018384:Oxidative Stress; D011247:Pregnancy; D012034:Refrigeration; D012662:Semen Preservation / Q000379:methods / Q000662:veterinary*; D013094:Spermatozoa / Q000187:drug effects / Q000502:physiology*; D014325:Tromethamine / Q000494:pharmacology
chemical_list: D003451:Cryoprotective Agents; D054709:Lecithins; D014325:Tromethamine; D019343:Citric Acid; D005632:Fructose
keywords: Bull; Lipid peroxidation; Semen extender; Soy lecithin; Sperm refrigeration