Cooling stored epididymal samples for several days allows facilities to transport and process genetic material post-mortem. Improvements to this practice allow the preservation of sperm from domestic cats, which are the ideal study model for wild felids. However, the modifications in spermatic features and the oxidative profile are not fully understood in cats. This information is necessary for the development of biotechniques, such as new extenders for cryopreservation. Therefore, the purpose of this study was to evaluate the spermatic and oxidative profile in samples from the epididymal cauda of domestic cats cooled at 5°C for 24, 48 and 72 hr. Spermatozoa were collected from the epididymis cauda. Evaluations consisted of computer-assisted sperm analysis (CASA), plasma membrane integrity (eosin/nigrosin), acrosome integrity (fast green/rose bengal), sperm morphology, sperm DNA integrity (toluidine blue), mitochondrial activity (3'3 diaminobenzidine), activity of the antioxidant enzymes glutathione peroxidase (GPx) and superoxide dismutase (SOD), measurement of lipid peroxidation (TBARS) and protein oxidation. A decrease in sperm motility parameters was observed after 72 hr of cooling (i.e. total and progressive) with a higher percentage of minor (37.7 ± 6.3%) and total defects (53.4 ± 6.3%). Additionally, a decrease in high mitochondrial activity (Class I: 16.6 ± 2.2%) occurred after 72 hr. The decrease in motility rates after a long cooling time probably was caused by the increase in sperm abnormalities. A long cooling time causes cold shock and mitochondrial exhaustion, but there was no observed change with the oxidative stress condition. Therefore, cat epididymal sperm stored at 5°C appear to maintain a high quality for up to 48 hr of cooling time.

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This study aimed to compare different selenium (Se) sources in the diet on boar's semen quality and fertility. For this, 28 boars aged 8 to 28 months were fed with the following dietary treatments for 95 days: 0.3 mg Se/kg as sodium selenite (SS, n = 14) and 0.3 mg Se/kg as hydroxy-selenomethionine (OH-SeMet, n = 14). During this period, two experiments were carried out. In experiment 1, the semen of all boars was evaluated every 2 weeks. Raw semen was initially evaluated for the processing of seminal doses, which were stored at 17 °C for 72 h, followed by sperm quality assessments. Furthermore, Se concentration and glutathione peroxidase (GPx) activity were measured in the seminal plasma. In experiment 2, 728 females were inseminated weekly with seminal doses from boars of the different experimental groups to further assess in vivo fertility and litter characteristics. Results demonstrated that boars fed OH-SeMet had more Se in their seminal plasma (p < 0.05), showing the greater bioavailability of the organic source in the male reproductive system. Moreover, boars fed OH-SeMet tended (p < 0.10) towards a higher total sperm count in the ejaculate (66.60 vs. 56.57 × 10 9 sperm), and the number of seminal doses (22.11 vs. 18.86; 3 × 10 9 sperm/dose) when compared to those fed SS. No effect of the dietary treatments was observed on GPx activity in seminal plasma (p > 0.05), as well as on raw and stored semen quality (p > 0.05). Under in vivo conditions, seminal doses from boars fed OH-SeMet tended (p < 0.10) towards a higher pregnancy rate at weeks 3, 5, and 8, and also resulted in a higher (p < 0.05) percentage of pregnant females in the overall period (99.30 vs. 97.00). In conclusion, the replacement of SS with OH-SeMet in boars' diet can improve sperm production and results in better reproductive performance for them, bringing greater productivity and profitability to artificial insemination centers and commercial pig farms.

Primeiramente gostaria de agradecer meus pais, Julieta e Hideyuki e meu irmão Allan. Todos esses anos de carinho, amor, dedicação e superação de obstáculos foram fundamentais para que eu alcançasse meus objetivos profissionais e pessoais. Sem o apoio deles, muitas das minhas conquistas e sonhos não poderiam ser concretizados. À minha namorada Fabiana, que me acompanhou nessa trajetória, por todo carinho, compreensão e parceria. Aos meus grandes companheiros de laboratório Henrique, Fabio , Raphaela, Roberta e Álvaro por cada momento juntos marcando essa amizade que cultivamos nesses anos de convivência dentro e fora da pós-graduação. Aos meus amigos, Num, Ask, Fuleco, Francis, Rick, Hideki, Lya, Egg, Leo, Jean, Lu e Irene por toda força que sempre me deram. Ao corpo docente da FMVZ-USP e todos os profissionais que me orientaram. Em especial aos professores Marcilio, Mayra, Claudia, Visintin, Cris, George e Pietro. Agradeço a todo apoio, dedicação e disponibilidade para transmitirem seus conhecimentos tanto para minha vida profissional quanto pessoal. À Harumi, Camila, Irailton, Thais, Clau e Luiz por todo suporte durante o mestrado, no projeto, nas atividades administrativas, na lida com os animais e na preparação das aulas. Por fim, gostaria de agradecer meu psicólogo Vitor, pela paciência e comprometimento em nossas reflexões, as quais me fizeram evoluir. O presente trabalho foi realizado com apoio da Coordenação de Aperfeiçoamento de Pessoal de Nível Superior -Brasil (CAPES) -Código de Financiamento 001.

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