Criopreservação de sêmen ovino com diferentes concentrações espermáticas associado ou não com ácido ascórbico

• Ano de defesa: 2013
• Autor(a) principal: Silva, Jaciara Campos da
• Orientador(a): Carvalho, Giovanni Ribeiro de
• Banca de defesa: Barbosa, Larissa Pires , Espeschit, Claudio José Borela , Costa, Eduardo Paulino da
• Tipo de documento: Tese
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal de Viçosa
• Programa de Pós-Graduação: Doutorado em Zootecnia
• Departamento: Genética e Melhoramento de Animais Domésticos; Nutrição e Alimentação Animal; Pastagens e Forragicul
• País: BR
• Palavras-chave em Português: Vitamina C; Ovinos; Ciopreservação
• Palavras-chave em Inglês: Vitamin C; Ram; Cyopreservation
• Área do conhecimento CNPq: CNPQ::CIENCIAS AGRARIAS::ZOOTECNIA::PRODUCAO ANIMAL
• Link de acesso: http://locus.ufv.br/handle/123456789/1829

Semen was collected at regular intervals from three Dorper rams in reproductive age and with excellent sperm characteristics in order to maximize ram semen cryopreservation while keeping their fertilizing ability. Their semen was cryopreserved in medium based on Tris-yolk with different sperm concentrations, supplemented or not with 2.5 mM vitamin C. Sperm concentration and antioxidant effect were evaluated. After each collection, the semen was diluted and analyzed with that medium, and then distributed along six experimental groups: G1 (control group) - 80 x 106 spermatozoa without vitamin C; G2 - 40 x106 without vitamin C; G3 - 20 x 106 without Vitamin C; G4 - 80 x 106 spermatozoa with vitamin C; G5 - 40 x106 with vitamin C; G6 - 20 x 106 with vitamin C. After dilutions, the semen was cooled to 5 oC, kept in a two-hour period of equilibrium, and then stored in previously identified and sealed 0.25 mL pellets. The pellets were frozen in liquid nitrogen vapor for 15 minutes, submerged in nitrogen, and then stored in cryogenic cylinder. The doses of semen in the groups were thawed at 37 oC for 30 seconds and subjected to in vitro tests: motility, vigor, morphology, membrane integrity by staining eosin/nigrosin, hypoosmotic test and thermoresistance test (TRT) at 37 oC for three hours. 180 crossbred ewes had their estrus induced and synchronized pharmacologically, using intravaginal sponges impregnated with 60 mg of medroxyprogesterone acetate (Progespon®, Coopers, Brazil) for seven days and applying 300 UI eCG (Sincroecg®, Ourofino, Brazil) and 0.125 mg of cloprostenol (Ciosin®, Coopers, Brazil) 24 hours before sponge removal. On the eighth day of treatment, the sheep received 300 UI hCG (Vetecor®, Hertape Calier, Brazil). The intrauterine inseminations occurred by means of laparoscopy 55 hours after sponge removal. 40 days after the inseminations, ultrasound examinations were performed to attest to pregnancy. In post-thaw motility, there was a significant difference (p<0.05) between group 4 (67.8 ± 3.9) and group 6 (62.9 ± 3.6). Motilities in the first hour of the thermoresistance test differed statistically (p<0.05) between groups 1 and 4, with mean and standard deviation of 61.7 ± 6.2 and 66.5 ± 3.7, respectively, and between groups 4 and 6 with values of the order of 66.5 ± 3.7 and 61.0 ± 2.9, respectively. Semen vigor in post-thaw and TTR did not change significantly (p>0.05) among groups, and nor did the membrane integrity tests. The reduction in sperm concentration from 80 to 40 and 20 million spermatozoa per insemination dose did not significantly change (p>0.05) in vivo fertility. No significant changes were observed in the groups supplemented with vitamin C (p> .05). It is concluded that the inclusion of 0.5 mg/ml ascorbic acid to the diluent medium did not improve either the characteristics or the fertility of the cryopreserved semen, and the dose of 20 million total spermatozoa was effective for use in laparoscopic FTAI in sheep.