Efeitos de diferentes doses e vias de administração de GnRH sobre a concentração sérica de LH, progesterona,taxas de ovulação e prenhez em vacas HPB
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Data
2019-01-15
Autores
Polizel, Fernando Franco [UNESP]
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Editor
Universidade Estadual Paulista (Unesp)
Resumo
O objetivo do presente trabalho foi verificar os efeitos da administração de meia dose de GnRH na submucosa da vulva sobre os níveis de LH, progesterona, dinâmica folicular ovariana e taxa de concepção em rebanho leiteiro, utilizando o protocolo ―Ovsynch‖, modificado. As vacas (n = 13) e novilhas (n = 11) foram pré-sincronizadas com duas injeções de PGF2α, com intervalo de 14 dias e 12 dias. Após a última prostaglandina, foi iniciado o protocolo ―Ovsynch‖, modificado pela inclusão de duas injeções de PGF2α. No momento da aplicação da segunda dose de GnRH (GnRH-2) os animais foram distribuídos de maneira homogênea para os grupos: controle (CN; n = 8), animais recebendo 2,5 mL de cloreto de sódio 0,9% por via im, intramuscular (IM; n = 8), injetado 10,5 µg de GnRH por via intramuscular e submucosa da vulva (SV; n = 8), recebendo 5,25 µg de GnRH. As amostras de sangue foram colhidas no D0, D7, D9 e D17 para determinação da concentração sérica de progesterona, e para o LH, foram colhidas em cinco momentos no D9 (M-40, M0, M40, M80 e M120 min). Quanto ao LH, não houve diferença significativa entre os grupos IM e SV em todos os momentos, os quais foram significativamente maiores do que o CN, enquanto no SV, maiores valores de média foram obtidos para a área sob a curva de LH (ASC-LH) em comparação com os grupos IM e CN. Não houve diferença significativa entre os grupos quanto à concentração de progesterona, independente do dia avaliado. Todos os grupos apresentaram o mesmo número de ovulação (6/8), porém, com menor média de tempo para IM e VS em comparação ao grupo controle. A taxa de concepção superior no grupo IM seguida por CN e VS. Concluindo, a administração de meia dose de GnRH na submucosa da vulva pode ser uma alternativa eficiente para a sincronização da ovulação em rebanho de leite.
The aim of this study was to verify the effects of low dose of GnRH administered in the vulva submucosa on LH and progesterone levels, ovarian dynamics and conception rate in dairy cattle using a modified Ovsynch protocol. Cows (n = 13) and heifers (n = 11) were pre-synchronized with two injections of PGF2α administered with a 14-days interval. Twelve days after the last prostaglandin dose a modified Ovsynch protocol was initiated and at the time of the second dose of GnRH (GnRH-2) the animals were homogeneously distributed to groups: control (CN; n = 8), receiving 2.5 mL of 0.9% sodium chloride, im, intramuscular (IM; n = 8,) receiving 10.5 μg of GnRH intramuscular; and vulva submucosa (VS; n = 8) with administration of 5.25 μg of GnRH. Blood samples were collected to determine serum progesterone concentration on D0, D7, D9 and D17, and the level of LH at five moments on D9 (M-40, M0, M40, M80 and M120 min). Higher levels of LH were observed in IM and VS groups in comparison with CN, however no significant difference was found between IM and VS for any time of evaluation. The higher mean value for the area under LH curve (AUC-LH) was found in VS than for IM and CN. There was no difference among groups for progesterone levels measured on in the different days of the protocol. The number of ovulated animals was similar among groups, but the time elapsed to ovulation was lower in IM and VS than in control group. The conception rate was higher in IM group, followed by CN and then VS. In conclusion, half dose of buserelin acetate in the vulva submucosa can be an effective alternative for ovulation synchronization in dairy catlle.
The aim of this study was to verify the effects of low dose of GnRH administered in the vulva submucosa on LH and progesterone levels, ovarian dynamics and conception rate in dairy cattle using a modified Ovsynch protocol. Cows (n = 13) and heifers (n = 11) were pre-synchronized with two injections of PGF2α administered with a 14-days interval. Twelve days after the last prostaglandin dose a modified Ovsynch protocol was initiated and at the time of the second dose of GnRH (GnRH-2) the animals were homogeneously distributed to groups: control (CN; n = 8), receiving 2.5 mL of 0.9% sodium chloride, im, intramuscular (IM; n = 8,) receiving 10.5 μg of GnRH intramuscular; and vulva submucosa (VS; n = 8) with administration of 5.25 μg of GnRH. Blood samples were collected to determine serum progesterone concentration on D0, D7, D9 and D17, and the level of LH at five moments on D9 (M-40, M0, M40, M80 and M120 min). Higher levels of LH were observed in IM and VS groups in comparison with CN, however no significant difference was found between IM and VS for any time of evaluation. The higher mean value for the area under LH curve (AUC-LH) was found in VS than for IM and CN. There was no difference among groups for progesterone levels measured on in the different days of the protocol. The number of ovulated animals was similar among groups, but the time elapsed to ovulation was lower in IM and VS than in control group. The conception rate was higher in IM group, followed by CN and then VS. In conclusion, half dose of buserelin acetate in the vulva submucosa can be an effective alternative for ovulation synchronization in dairy catlle.
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Palavras-chave
Buserelina, Meia dose, Hormônio Luteinizante, Ovulação, "Ovsynch", Buserelin, Half dose, Luteinizing Hormone, Ovulation, Ovsynch