Efeito de diferentes tempos de resfriamento pré-congelamento na viabilidade espermática do sêmen descongelado de caprino

• Autor(a) principal: Oliveira, Giselle Dias de
• Data de Publicação: 2013
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: LOCUS Repositório Institucional da UFV
• Texto Completo: http://locus.ufv.br/handle/123456789/5148
• topic: Espermatozoides; Criopreservação; Tempo de equilíbrio; Sperm; Cryopreservation; Balancing time; CNPQ::CIENCIAS AGRARIAS::MEDICINA VETERINARIA

The experiment was conducted at the Animal Reproduction Section of Veterinary Department, UFV, Viçosa, MG. The aim of the study was develop a technique of cryopreservation in order to improve the viability of goat semen after thawing. Were used four treatments: T1, cooling time of 1 h; T2, cooling time of 2 h; T3, cooling time of 4 h; and T4, with cooling time of 6 h before freezing. The semen was collected from four adult goats with three years old, totaling five collections using as dummy an adult male and the artificial vagina method, with the collections being conducted during the natural breeding season (April and May 2012). Were evaluated physical characteristics of semen immediately after collection and after thawing. After thawing, were also performed four complementary tests: heat resistance (TTR), hyposmotic (HOST), membrane integrity (INT), and morphological. The average values obtained for the fresh semen as the volume (mL), motility (%), sperm vigor (0-5) and sperm concentration (x109 total) were within the standards set by the Brazilian College of Animal Reproduction (1998), 1,5; 85%, 3,78; 3,3 billion / ml, respectively. The postthaw sperm motility and sperm vigor in the T2 showed mot. (38.0 ± 3.3) and vigor (2.2 ± 0.1), T3 mot. (52.3 ± 4.7) vigor (2.4 ± 0.1) and T4 mot. (47.0 ± 5.0) and vigor (2.4 ± 0.1), also proved within the values recommended by CBRA (1998). It was observed that the semen had resistance until the time 180 minutes in all treatments throughout the TTR. However, semen samples in treatments 3 and 4 were the ones that obtained better results. Regression analysis was performed to strengthen the results of the TTR time zero, where a greater curve was observed on time 265 minutes cooling, in other words, around 4 h and 25 minutes. The complementary tests (HOST, morphological and INT) performed in this study with different cooling times showed differences (P <0.05) between treatments only in INT test (29,7±3,3; 39,8±4,6; 50,0±5,1 e 56,5±4,1). Positive correlation was observed between motility and sperm vigor, and between motility and test INT. It is concluded that the cooling time of goat semen in times of 4 and 6 h has promoted better sperm cell viability after thawing of semen, increasing longevity of the spermatozoa.