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Ovulação Múltipla e Transferência de Embriões em ovinos da raça Suffolk em Portugal
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A Ovulação Múltipla e Transferência de Embriões (OMTE) constitui uma biotécnica reprodutiva de relevância na ovinocultura. A Suffolk é uma raça ovina conhecida mundialmente pela sua aptidão cárnica e, estas características de alto valor genético poderão beneficiar de uma ferramenta como a OMTE para um melhoramento genético e um aumento da eficiência reprodutiva destes ovinos. Neste estudo, foram incluídos 45 programas de superovulação e recolha de embriões, considerando 34 fêmeas dadoras da raça Suffolk. Destes, em 89,9% foi observada resposta positiva à ovulação múltipla (n = 40). Considerando apenas os programas em que as ovelhas reponderam positivamente, foi analisada a influência de parâmetros como: a sazonalidade; o método de beneficiação (monta ou Inseminação Artificial Laparoscópica -IAL); o tipo de sémen utilizado na IAL; o número de tratamentos Superovulatórios a que foram sujeitas as dadoras e o número de partos; sobre o total de estruturas recolhidas, o número de embriões viáveis, a expressão da resposta ovulatória (número de Corpos Lúteos - CL) e, em algumas circunstâncias, o número de estruturas não fertilizadas e a eficácia de recolha. Relativamente aos programas de Transferência de Embriões, o estudo incluiu 31, envolvendo 16 ovelhas recetoras, cruzadas de Suffolk e foram transferidos 62 embriões. Foi avaliada a influência de vários fatores sobre o diagnóstico de gestação aos 30 dias e sobre a taxa de sobrevivência embrionária: o número de transferências por recetora, a idade, o grau de sincronia, o número de CL presentes nos ovários após a sincronização, o tipo de embriões (frescos ou congelados) e o número de embriões transferidos por recetora. Os resultados evidenciaram diferenças estatisticamente significativas na quantidade de embriões recolhidos em função da sazonalidade (3,64 ± 0,88 na época reprodutiva vs. 0,17 ± 0,11 na contra-estação). Verificaram-se, ainda, diferenças consideráveis consoante o método de beneficiação, monta ou IAL, na quantidade de oócitos (6,46 ± 0,91 vs. 2,57 ± 0,75) e embriões (1,27 ± 0,71 vs. 5,07 ± 1,31) recolhidos. Não foram observadas diferenças estatisticamente relevantes nas restantes variáveis analisadas, embora algumas tenham apresentado tendências crescentes ou decrescentes em função de determinados parâmetros. Concluiu-se que a OMTE é uma técnica de aplicação viável nas ovelhas Suffolk, em Portugal, com taxas de desempenho reprodutivo compatíveis com as descritas na bibliografia. Contudo, a otimização dos programas deve considerar a sazonalidade e o método de beneficiação com vista a maximizar a taxa de sucesso global da técnica
Multiple Ovulation and Embryo Transfer (MOET) is a reproductive biotechnological tool of significant relevance in sheep production. The Suffolk breed is globally recognized for its meat-producing aptitude and, such high genetic value traits can greatly benefit from the application of MOET to enhance genetic improvement and increase reproductive efficiency in sheep. A total of 45 superovulation and embryo collection programmes were carried out, involving 34 Suffolk donor ewes. A positive response to multiple ovulation was observed in 89.9% of the cases (n = 40). Consequently, only the programmes in which the donor ewes exhibited a positive superovulatory response were included in the analysis. The influence of factors such as seasonality; mating method (natural mating vs. artificial insemination – AI); semen type used in AI; the number of superovulatory treatments administered to the donors; and the number of lambings was assessed in relation to the total number of recovered structures, the number of viable embryos, the magnitude of the ovulatory response (number of corpora lutea), and, in some cases, the number of unfertilised structures and recovery efficiency. Regarding the embryo transfer programs, 31 procedures were included, involving 16 Suffolk-cross recipient ewes and 62 embryos were transferred. The study evaluated the influence of number of embryo transfers per recipient, age, estrous synchrony, number of CL present after synchronization, embryo type (fresh or cryopreserved), and number of embryos transferred per recipient on pregnancy diagnosis at 30 days and embryo survival rate. The results revealed statistically significant differences in the number of embryos recovered according to seasonality (3.64 ± 0.88 during the breeding season vs. 0.17 ± 0.11 in the non-breeding season). Marked differences were also observed depending on the breeding method, with natural mating and AI yielding different numbers of oocytes (6.46 ± 0.91 vs. 2.57 ± 0.75) and embryos (1.27 ± 0.71 vs. 5.07 ± 1.31). No statistically significant differences were found for the remaining variables, although some showed increasing or decreasing trends in relation to specific parameters. It is concluded that MOET is a feasible and applicable technique for Suffolk sheep under national production conditions, yielding reproductive performance rates consistent with those reported in the literature. Nevertheless, program optimization should consider seasonality and breeding method in order to maximize the overall success rate of the technique
Multiple Ovulation and Embryo Transfer (MOET) is a reproductive biotechnological tool of significant relevance in sheep production. The Suffolk breed is globally recognized for its meat-producing aptitude and, such high genetic value traits can greatly benefit from the application of MOET to enhance genetic improvement and increase reproductive efficiency in sheep. A total of 45 superovulation and embryo collection programmes were carried out, involving 34 Suffolk donor ewes. A positive response to multiple ovulation was observed in 89.9% of the cases (n = 40). Consequently, only the programmes in which the donor ewes exhibited a positive superovulatory response were included in the analysis. The influence of factors such as seasonality; mating method (natural mating vs. artificial insemination – AI); semen type used in AI; the number of superovulatory treatments administered to the donors; and the number of lambings was assessed in relation to the total number of recovered structures, the number of viable embryos, the magnitude of the ovulatory response (number of corpora lutea), and, in some cases, the number of unfertilised structures and recovery efficiency. Regarding the embryo transfer programs, 31 procedures were included, involving 16 Suffolk-cross recipient ewes and 62 embryos were transferred. The study evaluated the influence of number of embryo transfers per recipient, age, estrous synchrony, number of CL present after synchronization, embryo type (fresh or cryopreserved), and number of embryos transferred per recipient on pregnancy diagnosis at 30 days and embryo survival rate. The results revealed statistically significant differences in the number of embryos recovered according to seasonality (3.64 ± 0.88 during the breeding season vs. 0.17 ± 0.11 in the non-breeding season). Marked differences were also observed depending on the breeding method, with natural mating and AI yielding different numbers of oocytes (6.46 ± 0.91 vs. 2.57 ± 0.75) and embryos (1.27 ± 0.71 vs. 5.07 ± 1.31). No statistically significant differences were found for the remaining variables, although some showed increasing or decreasing trends in relation to specific parameters. It is concluded that MOET is a feasible and applicable technique for Suffolk sheep under national production conditions, yielding reproductive performance rates consistent with those reported in the literature. Nevertheless, program optimization should consider seasonality and breeding method in order to maximize the overall success rate of the technique
Descrição
Dissertação de Mestrado Integrado em Medicina veterinária, área científica de Clínica
Palavras-chave
Ovinos OMTE Estro Sincronização Superovulação Embriões CL Taxa de Sobrevivência Gestação Sheep MOET Oestrus Synchronization Superovulation Embryos CL Survival rate Pregnancy