Large-scale programs for recipients of in vitro-produced embryos

In vitro embryo production (IVEP) has become an accessible option for meat and milk producers, and Brazil is now the leader of IVEP worldwide. Recipient females represent one of the most significant costs in embryo transfer (ET) programs. Thus, hormonal protocols may increase the proportion of suitable recipients to receive embryos and improve the efficiency of IVEP program s. Besides improving the amount of available recipients, it is important to select high quality animals. Due to the great demand, the type of females that were considered ideal for ET has become scarce, especially for large-scale programs. Therefore, new approaches have successfully emerged, as the use of Nelore cows recently calved as embryo recipients. For being the most numerous category in Brazil, these animals can be acquired for fair prices. Embryo production from slaughterhouse ovaries also represents an innovative strategy for large-scale IVEP. With the use of sorted sperm and large amount of pregnancies, is has become an interesting alternative compared to AI. In this article, recent advances in embryo IVP are discussed, as well as some of the most used hormonal protocols for estrus synchronization of recipients in large-scale IVEP programs.

Large-scale programs for recipients of in vitro-produced embryos

In vitro embryo production (IVEP) has become an accessible option for meat and milk producers, and Brazil is now the leader of IVEP worldwide. Recipient females represent one of the most significant costs in embryo transfer (ET) programs. Thus, hormonal protocols may increase the proportion of suitable recipients to receive embryos and improve the efficiency of IVEP program s. Besides improving the amount of available recipients, it is important to select high quality animals. Due to the great demand, the type of females that were considered ideal for ET has become scarce, especially for large-scale programs. Therefore, new approaches have successfully emerged, as the use of Nelore cows recently calved as embryo recipients. For being the most numerous category in Brazil, these animals can be acquired for fair prices. Embryo production from slaughterhouse ovaries also represents an innovative strategy for large-scale IVEP. With the use of sorted sperm and large amount of pregnancies, is has become an interesting alternative compared to AI. In this article, recent advances in embryo IVP are discussed, as well as some of the most used hormonal protocols for estrus synchronization of recipients in large-scale IVEP programs.(AU)

Desempenho reprodutivo de ovelhas mestiças lanadas e deslanadas submetidas a protocolo hormonal a base de progestágeno e eCG, durante a contraestação reprodutiva / Reproductive performance of woolly and hairless crossbred ewes treated with an exogenous progestagen and eCG hormone during the non-breeding season

Este trabalho teve como objetivo avaliar o desempenho reprodutivo de ovelhas mestiças lanadas e deslanadas submetidas a um protocolo hormonal a base de progestágeno e eCG durante a contraestação reprodutiva. Ovelhas mestiças (n=48), sem raça definida, foram divididas em dois tratamentos, considerando-se a presença (G-Lanada, n=25) ou ausência de lã (G-Deslanada, n=23). As ovelhas foram submetidas a um tratamento hormonal de indução/sincronização de estro, que consistiu na colocação do dispositivo intravaginal em dia aleatório do ciclo estral (D0). No D7, foi administrado eCG e d-cloprostenol. No D9, o dispositivo foi retirado e após 12 h os machos foram introduzidos no lote (proporção 1:6), nos dias 10, 11 e 12. Posteriormente, os machos foram separados das fêmeas por dez dias e então reintroduzidos no lote por mais 45 dias. A taxa de apresentação de estro e de prenhez resultantes da sincronização foi 84,0 e 36,0% vs. 87,0 e 56,6%, G-Lanada vs. G-Deslanada (p>0,05). A taxa de prenhez total, após repasse com os reprodutores foi 68,0 vs. 91,3%, G-Lanada vs. G-Deslanada (p<0,05). Conclui-se que ovelhas mestiças deslanadas tratadas com protocolo hormonal durante a contraestação apresentaram desempenho reprodutivo superior ao de ovelhas mestiças lanadas.

The aim of this study was to evaluate the reproductive performance of woolly and hairless crossbred ewes treated with an exogenous progestagen and eCG hormone during the non-breeding season. Mixed breed ewes (n = 48) were assigned into two treatments considering the presence (G-Woolly, n = 25) or absence of wool (G-Hairless, n = 23). The ewes underwent hormone treatment to induction/synchronization of estrus, which consisted of the insertion of an intravaginal device randomly at the estrous cycle (D0). On Day 7, ewes were injected with eCG and d-cloprostenol. On Day 9, the device was removed and males were introduced into the herd (proportion of 1:6) twelve hours later during days 10, 11 and 12. After Day 12, males were separated from females for ten days and later reintroduced into the herd for 45 days. The rate of onset of estrus and the pregnancy rate from the synchronization was 84.0 and 36.0% vs. 87.0 and 56.6%, G-Woolly vs. G-Hairless (p> 0.05). The total pregnancy rate after male reintroduction was 68.0 vs. 91.3%, G-Woolly vs. G-Hairless (p< 0.05). In conclusion hairless crossbred ewes treated with the exogenous progestagen and eCG hormone during the non-breeding season presented higher reproductive performance compared to woolly crossbred ones.

Reproductive performance of woolly and hairless crossbred ewes treated with an exogenous progestagen and eCG hormone during the non-breeding season / Desempenho reprodutivo de ovelhas mestiças lanadas e deslanadas submetidas a protocolo hormonal a base de progestágeno e eCG, durante a contraestação reprodutiva

The aim of this study was to evaluate the reproductive performance of woolly and hairless crossbred ewes treated with an exogenous progestagen and eCG hormone during the non-breeding season. Mixed breed ewes (n = 48) were assigned into two treatments considering the presence (G-Woolly, n = 25) or absence of wool (G-Hairless, n = 23). The ewes underwent hormone treatment to induction/synchronization of estrus, which consisted of the insertion of an intravaginal device randomly at the estrous cycle (D0). On Day 7, ewes were injected with eCG and d-cloprostenol. On Day 9, the device was removed and males were introduced into the herd (proportion of 1:6) twelve hours later during days 10, 11 and 12. After Day 12, males were separated from females for ten days and later reintroduced into the herd for 45 days. The rate of onset of estrus and the pregnancy rate from the synchronization was 84.0 and 36.0% vs. 87.0 and 56.6%, G-Woolly vs. G-Hairless (p> 0.05). The total pregnancy rate after male reintroduction was 68.0 vs. 91.3%, G-Woolly vs. G-Hairless (p 0.05). In conclusion hairless crossbred ewes treated with the exogenous progestagen and eCG hormone during the non-breeding season presented higher reproductive performance compared to woolly crossbred ones.

Este trabalho teve como objetivo avaliar o desempenho reprodutivo de ovelhas mestiças lanadas e deslanadas submetidas a um protocolo hormonal a base de progestágeno e eCG durante a contraestação reprodutiva. Ovelhas mestiças (n=48), sem raça definida, foram divididas em dois tratamentos, considerando-se a presença (G-Lanada, n=25) ou ausência de lã (G-Deslanada, n=23). As ovelhas foram submetidas a um tratamento hormonal de indução/sincronização de estro, que consistiu na colocação do dispositivo intravaginal em dia aleatório do ciclo estral (D0). No D7, foi administrado eCG e d-cloprostenol. No D9, o dispositivo foi retirado e após 12 h os machos foram introduzidos no lote (proporção 1:6), nos dias 10, 11 e 12. Posteriormente, os machos foram separados das fêmeas por dez dias e então reintroduzidos no lote por mais 45 dias. A taxa de apresentação de estro e de prenhez resultantes da sincronização foi 84,0 e 36,0% vs. 87,0 e 56,6%, G-Lanada vs. G-Deslanada (p>0,05). A taxa de prenhez total, após repasse com os reprodutores foi 68,0 vs. 91,3%, G-Lanada vs. G-Deslanada (p 0,05).Conclui-se que ovelhas mestiças deslanadas tratadas com protocolo hormonal durante a contraestação apresentaram desempenho reprodutivo superior ao de ovelhas mestiças lanadas.

Reproductive performance of woolly and hairless crossbred ewes treated with an exogenous progestagen and eCG hormone during the non-breeding season / Desempenho reprodutivo de ovelhas mestiças lanadas e deslanadas submetidas a protocolo hormonal a base de progestágeno e eCG, durante a contraestação reprodutiva

The aim of this study was to evaluate the reproductive performance of woolly and hairless crossbred ewes treated with an exogenous progestagen and eCG hormone during the non-breeding season. Mixed breed ewes (n = 48) were assigned into two treatments considering the presence (G-Woolly, n = 25) or absence of wool (G-Hairless, n = 23). The ewes underwent hormone treatment to induction/synchronization of estrus, which consisted of the insertion of an intravaginal device randomly at the estrous cycle (D0). On Day 7, ewes were injected with eCG and d-cloprostenol. On Day 9, the device was removed and males were introduced into the herd (proportion of 1:6) twelve hours later during days 10, 11 and 12. After Day 12, males were separated from females for ten days and later reintroduced into the herd for 45 days. The rate of onset of estrus and the pregnancy rate from the synchronization was 84.0 and 36.0% vs. 87.0 and 56.6%, G-Woolly vs. G-Hairless (p> 0.05). The total pregnancy rate after male reintroduction was 68.0 vs. 91.3%, G-Woolly vs. G-Hairless (p 0.05). In conclusion hairless crossbred ewes treated with the exogenous progestagen and eCG hormone during the non-breeding season presented higher reproductive performance compared to woolly crossbred ones.

Este trabalho teve como objetivo avaliar o desempenho reprodutivo de ovelhas mestiças lanadas e deslanadas submetidas a um protocolo hormonal a base de progestágeno e eCG durante a contraestação reprodutiva. Ovelhas mestiças (n=48), sem raça definida, foram divididas em dois tratamentos, considerando-se a presença (G-Lanada, n=25) ou ausência de lã (G-Deslanada, n=23). As ovelhas foram submetidas a um tratamento hormonal de indução/sincronização de estro, que consistiu na colocação do dispositivo intravaginal em dia aleatório do ciclo estral (D0). No D7, foi administrado eCG e d-cloprostenol. No D9, o dispositivo foi retirado e após 12 h os machos foram introduzidos no lote (proporção 1:6), nos dias 10, 11 e 12. Posteriormente, os machos foram separados das fêmeas por dez dias e então reintroduzidos no lote por mais 45 dias. A taxa de apresentação de estro e de prenhez resultantes da sincronização foi 84,0 e 36,0% vs. 87,0 e 56,6%, G-Lanada vs. G-Deslanada (p>0,05). A taxa de prenhez total, após repasse com os reprodutores foi 68,0 vs. 91,3%, G-Lanada vs. G-Deslanada (p 0,05).Conclui-se que ovelhas mestiças deslanadas tratadas com protocolo hormonal durante a contraestação apresentaram desempenho reprodutivo superior ao de ovelhas mestiças lanadas.