Efeito de diferentes curvas de resfriamento, tempos de equilíbrio e crioprotetores permeáveis no congelamento de espermatozóides de caprinos

• Autor(a) principal: Rovay, Herbert
• Data de Publicação: 2006
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: LOCUS Repositório Institucional da UFV
• Texto Completo: http://locus.ufv.br/handle/123456789/5714
• topic: Equilíbrio; Espermatozóide; Crioprotetores; Resfriamento; Equilibration; Spermatozoa; Cryoprotectants; Cooling; CNPQ::CIENCIAS AGRARIAS::MEDICINA VETERINARIA::REPRODUCAO ANIMAL

The aim of this study was to evaluate the effect of different cooling rates, equilibration times and permeating cryoprotectants on motility characteristics and plasma membrane integrity of cryopreserved goat spermatozoa. Three experiments were designed. In the first one was evaluated the effect of different cooling methods on goat semen cryopreservation. A total of 20 ejaculates from Saanen (n = 2) and Alpine (n = 2) goats were frozen using a standard dry skim milk yolk diluent with 5% glycerol. Aliquots of the extended semen were then cooled using two different cooling methods (PR1; Becker or PR2; Fürst, 2002), before being frozen in liquid nitrogen. The semen was evaluated by total motility, vigor and the response to hypoosmotic solution test (HOST), live/dead stain and thermo-resistance test (TRT), before and after thaw. In this experiment the cooling method PR2 protected cell viability better them PR1 during the criopreservation process, reducing cold shock damage and improving the cryosurvival of goat spermatozoa. In the second experiment was evaluated the effect of different equilibration times on motility characteristics and plasma membrane integrity of cryopreserved goat spermatozoa. A total of 20 ejaculates from Saanen (n = 2) and Alpine (n = 2) goats were frozen using a standard dry skim milk yolk diluent with 5% glycerol. Aliquots of the extended semen were then cooled using the cooling methodology described by Fürst (2002) and remained at the temperature of 5-4 °C by a period of 15 minutes (TE1) or 75 minutes (TE2). The semen was evaluated by total motility, vigor and the response to hypoosmotic solution test (HOST), live/dead stain and thermoresistance test (TRT), before and after thaw. In this experiment the equilibration time of 75 minutes protected the cell viability better than the period of 15 minutes during the criopreservation process, improving the cryosurvival of goat spermatozoa. In the third experiment was evaluated the effect of the glycerol (G) and ethylene glycol (EG), on motility characteristics of cryopreserved goat spermatozoa by the in vitro semen analyses. A total of 20 ejaculates from Saanen (n = 2) and Alpine (n = 2) goats were frozen using a standard dry skim milk-yolk diluent with 5% glycerol. Aliquots of the extended semen were then cooled using the cooling methodology described by Fürst (2002). The semen was evaluated by total motility, vigor and the response to hypoosmotic solution test (HOST), live/dead stain and thermo-resistance test (TRT), before and after thaw. In this experiment EG promoted a better protection of the spermatic cell viability during the cryopreservation than the G. In conclusion the use of the cooling method PR2 associated with the one hour equilibration period and the ethylene glycol improved the motility characteristics and integrity of plasma membrane, increasing the number of viable goat spermatozoa after cryopreservation.