RESUMEN

Breeding mares with cryopreserved semen requires specialized equipment for storage and thawing and more intensive mare management. The objectives of this study were (1) evaluate the longevity of frozen stallion semen once it had been thawed, extended, and maintained at 5°C for 48 hours in a passive cooling container, and (2) determine fertility potential of frozen semen that had been thawed, extended, and used to inseminate mares after 24 hours of cooled storage. Eight ejaculates were collected and aliquots were cooled in either INRA96 and CryoMax LE minus cryoprotectant at a concentration of 50 million total sperm/mL. The remainder of the ejaculate was frozen in CryoMax LE extender at a concentration of 200 million total sperm/mL. Semen was thawed using 1 of 3 thawing protocols, and diluted to a concentration of 50 million total sperm/mL in either INRA96 or CryoMax LE minus cryoprotectant and cooled to 5°C. Sperm motility was evaluated at 24 and 48 hours. Eight mares were inseminated over two estrous cycles using frozen semen that had been thawed, extended in INRA96, and cooled for 24 hours. There was no difference in progressive motility at 24 or 48 hours of cooled-storage post-thaw between the 3 thawing protocols. An overall per cycle pregnancy rate of 56% (9/16 cycles) was achieved using frozen-thawed semen that had been extended and cooled for 24 hours. In summary, frozen stallion sperm was thawed, extended, and cooled to 5°C for 24 hours and still maintained adequate (>30%) sperm motility and fertility.

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RESUMEN

This study was conducted to optimize the cryopreservation of epididymal bison sperm harvested in the field. In the first experiment, epididymal bison sperm were treated with or without seminal plasma (n = 6) and cooled to 5 °C over 2 hours. In a separate experiment, glycerol was added at different times and sperm was held at 5 °C for different periods of time before cryopreservation (n = 11). In addition, epididymal sperm frozen with and without seminal plasma (n = 6) and after 4, 24, and 48 hours (n = 5) of equilibration at 5 °C, were evaluated for their in vitro fertilizing ability. Post-thaw motility of bison epididymal sperm was similar when cryopreserved with or without seminal plasma or when glycerol was added at either 0, 4, 24, or 48 hours before freezing (P > 0.05). However, sperm incubated at 5 °C for 24 hours before freezing exhibited higher percentages of motile sperm (44% vs. 35% for 4 hours or 48 hours, P < 0.05). Fertilization rates of bison oocytes were not different for any treatments. Chilling the whole epididymis for 24 or 48 hours resulted in complete loss of sperm viability. In conclusion, bison epididymal sperm can be chilled outside of the epididymis for at least 48 hours before cryopreservation without compromising post-thaw sperm motility providing flexibility for technicians performing field collections.

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RESUMEN

This study evaluated the effect of adding different concentration of cholesterol-loaded-cyclodextrin (CLC) on sperm quality after thawing. Thirty ejaculates were diluted, centrifuged and resuspended to 120 million cells/mL in a Tris diluent. Semen was treated with 0 (Control), 0.75, 1.5, 3.0, 4.5, 6.0 or 7.5 mg of CLC. Then, the samples were cooled at 4ºC for 2 h, diluted with Tris-egg yolk and 2% glycerol, packaged into 0.5 mL straws, frozen in liquid nitrogen (N2) vapor for 20 min before being plunged into N2. Straws were thawed at 37ºC for 30 sec, and evaluated for thermal resistance test (TRT); progressive motility using CASA; hypoosmotic test and for binding capacity of sperm to perivitelline membrane (PM). The variables were determined using ANOVA at 5% probability. Higher percentage of motile sperm were maintained after thawing and TTR when 0.75 mg CLC was added, evaluated at 0, 60 and 120 min of incubation (50.4, 33.8 and 22.5%, respectively) compared to other treatments (P < 0.05). The percentage of coiling was higher in sperm treated with 6.0 and 7.0 mg of CLC than other treatments (P < 0.05). Addition of 0.75 mg CLCs also resulted in more sperm binding to the PM after cryopreservation than control sperm (166 vs 65; P < 0.05). However, when the spermatozoa binding potential was determined on a motile sperm basis by dividing the average number of spermatozoa bound to PM for each bucks by the percentage of motile spermatozoa, CLC treatment provided higher binding efficiency (1.52) than control (1.00; P<0.05). In conclusion, CLCs improved the percentage of post-thaw of motility in caprine sperm as well as increased the number of sperm that bind to PM. Addition of 0.75 mg of CLC to caprine sperm prior to cryopreservation improved the quality sperm motility for up to 2 h.(AU)

Este estudo teve como objetivo avaliar o efeito da adição do colesterol carreado com a ciclodextrina (CCC) sobre a melhoria da qualidade espermática após a descongelação. Trinta ejaculados foram diluídos, centrifugados e ressuspendidos com Tris para concentração de 120 x 106 células/mL. O sêmen foi tratado com 0, 0,75, 1,5, 3,0, 4,5, 6,0 ou 7,5 mg de CCC. Em seguida, as amostras foram resfriadas a 4ºC durante 2 horas, diluídas com Tris-Gema de ovo e 2% de glicerol, envasadas e colocadas sobre o vapor do nitrogênio líquido (N2) por 20 min e depois mergulhadas no N2 . As amostras foram descongeladas a 37ºC por 30s, e avaliadas quanto: o teste de termorresistência (TRT); motilidade progressiva utilizando CASA; teste hiposmótico e a capacidade de ligação dos espermatozoides à membrana perivitelina (MP). As variáveis foram analisadas por meio da ANOVA e os tratamentos comparados a 5% de probabilidade. A motilidade dos espermatozoides (50,4; 33,8 e 22,5%) foi maior nas amostras tratadas com 0,75 mg de CCC após 0, 60 e 120 min de incubação quando comparado com demais tratamentos (P < 0,05). As amostras tratadas com 6,0 e 7,0 mg de CCC apresentaram maior dobramento de cauda que os demais tratamentos (P < 0,05). A capacidade de ligação dos espermatozoides a MP foi maior no tratamento com 0,75 mg CCC comparado ao controle (166 vs 65; P < 0,05). No entanto, quando o potencial de ligação dos espermatozoides foi determinado dividindo o número médio de espermatozoides ligados a MP sobre o percentual de espermatozoides móveis, o tratamento com CCC proporcionou maior eficiência (1,52) do que o controle (1,00; P < 0,05). A adição de 0,75 mg de CCC no sêmen fresco de caprino antes da criopreservação melhorou a motilidade espermática após a criopreservação até 2 horas.(AU)

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RESUMEN

Este estudo teve como objetivo avaliar o efeito da adição do colesterol carreado com a ciclodextrina (CCC) sobre a melhoria da qualidade espermática após a descongelação. Trinta ejaculados foram diluídos, centrifugados e ressuspendidos com Tris para concentração de 120 x 106 células/mL. O sêmen foi tratado com 0, 0,75, 1,5, 3,0, 4,5, 6,0 ou 7,5 mg de CCC. Em seguida, as amostras foram resfriadas a 4°C durante 2 horas, diluídas com Tris-Gema de ovo e 2% de glicerol, envasadas e colocadas sobre o vapor do nitrogênio líquido (N2 ) por 20 min e depois mergulhadas no N2 . As amostras foram descongeladas a 37°C por 30s, e avaliadas quanto: o teste de termorresistência (TRT); motilidade progressiva utilizando CASA; teste hiposmótico e a capacidade de ligação dos espermatozoides à membrana perivitelina (MP). As variáveis foram analisadas por meio da ANOVA e os tratamentos comparados a 5% de probabilidade. A motilidade dos espermatozoides (50,4; 33,8 e 22,5%) foi maior nas amostras tratadas com 0,75 mg de CCC após 0, 60 e 120 min de incubação quando comparado com demais tratamentos (P<0,05). As amostras tratadas com 6,0 e 7,0 mg de CCC apresentaram maior dobramento de cauda que os demais tratamentos (P<0,05). A capacidade de ligação dos espermatozoides a MP foi maior no tratamento com 0,75 mg CCC comparado ao controle (166 vs 65; P <0,05). No entanto, quando o potencial de ligação dos espermatozoides foi determinado dividindo o número médio de espermatozoides ligados a MP sobre o percentual de espermatozoides móveis, o tratamento com CCC proporcionou maior eficiência (1,52) do que o controle (1,00; P < 0,05). A adição de 0,75 mg de CCC no sêmen fresco de caprino antes da criopreservação melhorou a motilidade espermática após a criopreservação até 2 horas.

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