Recent advances in treatments for resynchronization of ovulation in small ruminants: a review.

Hormonal methodologies to control small ruminants' estrous cycle are worldwide used and evolved, adjusting the application to the precise female physiological moments to enhance reproductive performance. The estrous cycle can be induced and/or synchronized, aiming for fixed-time artificial insemination, or based on estrus behavior signs for insemination, natural or guided mating. Successive protocols can be performed to resynchronize ovulation and increase reproductive outcomes in females that failed to conceive. These recently developed treatments aim to resynchronize the ovulation as earlier as non-pregnancy is detected. The present review aimed to summarize the recent advances and main findings regarding resynchronization protocols used in small ruminants. Lastly, we present future perspectives and new paths to be studied in the subject. The resynchronization treatment is still a growing field in small ruminant reproduction, nevertheless, some enhancements are found in the reproductive outcome, showing that such protocols can be successfully used in sheep and goat production.

Recent advances in treatments for resynchronization of ovulation in small ruminants: a review

Hormonal methodologies to control small ruminants' estrous cycle are worldwide used and evolved, adjusting the application to the precise female physiological moments to enhance reproductive performance. The estrous cycle can be induced and/or synchronized, aiming for fixed-time artificial insemination, or based on estrus behavior signs for insemination, natural or guided mating. Successive protocols can be performed to resynchronize ovulation and increase reproductive outcomes in females that failed to conceive. These recently developed treatments aim to resynchronize the ovulation as earlier as non-pregnancy is detected. The present review aimed to summarize the recent advances and main findings regarding resynchronization protocols used in small ruminants. Lastly, we present future perspectives and new paths to be studied in the subject. The resynchronization treatment is still a growing field in small ruminant reproduction, nevertheless, some enhancements are found in the reproductive outcome, showing that such protocols can be successfully used in sheep and goat production.(AU)

Indução do estro e métodos para controle das fases do ciclo estral em cadelas / Induction of estrus and methods for control of estrous cycle in bitches

Os estudos referentes à manipulação do ciclo estral em cadelas aumentaram significativamente ao longo dos anos. Com a criação comercial de cães ganhando destaque a nível internacional, há uma busca por incrementação no manejo reprodutivo desses animais, bem como o tratamento de condições prejudiciais à fertilidade na cadela, outro motivo é o fato dos cães domésticos também poderem atuar como modelos experimentais para várias espécies de canídeos silvestres e para o homem. Isso tem sido associado a uma maior disponibilidade de fármacos indutores de estro, como agonistas dopaminérgicos, análogos do GnRH e protocolos com gonadotrofinas, a exemplo do eCG. A manipulação eficiente do ciclo estral é de grande valia para o aperfeiçoamento das biotecnologias da reprodução nessa espécie e, mesmo com o avanço das pesquisas, os fármacos ainda não foram suficientemente testados para se obter o conhecimento das suas completas ações, bem como para apontar seus pontos fortes e fracos. Essa revisão de literatura tem como objetivo ampliar as informações a respeito do assunto, abordando aspectos relacionados à fisiologia e endocrinologia reprodutiva na cadela, as particularidades do ciclo estral canino, descrevendo as alterações anatômicas, citológicas e hormonais, bem como os principais moduladores do ciclo estral de cadelas, apontando seus efeitos e controvérsias e proporcionando o surgimento de protocolos eficientes para a indução do estro nesses animais.(AU)

Studies on the manipulation of estrous cycle in bitches have increased significantly over the years. With the commercial breeding of dogs gaining prominence internationally, there has been a need for improvement of the reproductive management of these animals, as well as the treatment of conditions which are detrimental to bitches fertility. Another reason is that domestic dogs can also act as experimental models to several species of wild dogs and to man. This has been associated with a greater availability of estrus-induction pharmacological drugs, such as dopamine agonists, GnRH analogue and protocols with gonadotropin, such as eCG. Efficient manipulation of the estrous cycles is of great importance for the improvement of the reproductive biotechnology in this species. Notwithstanding the advances in research, the drugs have not yet been sufficiently tested in order to have their action fully understood, nor to identify their strengths and weakness. This literature review aims to expand the information on subject, addressing aspects related to the reproductive physiology and endocrinology in bitches, as well as the main modulators of the estrous cycle, pointing out their effects and differences and providing information for the creation of new efficient protocols for induction of estrus in those animals.(AU)

Indução do estro e métodos para controle das fases do ciclo estral em cadelas / Induction of estrus and methods for control of estrous cycle in bitches

Os estudos referentes à manipulação do ciclo estral em cadelas aumentaram significativamente ao longo dos anos. Com a criação comercial de cães ganhando destaque a nível internacional, há uma busca por incrementação no manejo reprodutivo desses animais, bem como o tratamento de condições prejudiciais à fertilidade na cadela, outro motivo é o fato dos cães domésticos também poderem atuar como modelos experimentais para várias espécies de canídeos silvestres e para o homem. Isso tem sido associado a uma maior disponibilidade de fármacos indutores de estro, como agonistas dopaminérgicos, análogos do GnRH e protocolos com gonadotrofinas, a exemplo do eCG. A manipulação eficiente do ciclo estral é de grande valia para o aperfeiçoamento das biotecnologias da reprodução nessa espécie e, mesmo com o avanço das pesquisas, os fármacos ainda não foram suficientemente testados para se obter o conhecimento das suas completas ações, bem como para apontar seus pontos fortes e fracos. Essa revisão de literatura tem como objetivo ampliar as informações a respeito do assunto, abordando aspectos relacionados à fisiologia e endocrinologia reprodutiva na cadela, as particularidades do ciclo estral canino, descrevendo as alterações anatômicas, citológicas e hormonais, bem como os principais moduladores do ciclo estral de cadelas, apontando seus efeitos e controvérsias e proporcionando o surgimento de protocolos eficientes para a indução do estro nesses animais.

Studies on the manipulation of estrous cycle in bitches have increased significantly over the years. With the commercial breeding of dogs gaining prominence internationally, there has been a need for improvement of the reproductive management of these animals, as well as the treatment of conditions which are detrimental to bitches’ fertility. Another reason is that domestic dogs can also act as experimental models to several species of wild dogs and to man. This has been associated with a greater availability of estrus-induction pharmacological drugs, such as dopamine agonists, GnRH analogue and protocols with gonadotropin, such as eCG. Efficient manipulation of the estrous cycles is of great importance for the improvement of the reproductive biotechnology in this species. Notwithstanding the advances in research, the drugs have not yet been sufficiently tested in order to have their action fully understood, nor to identify their strengths and weakness. This literature review aims to expand the information on subject, addressing aspects related to the reproductive physiology and endocrinology in bitches, as well as the main modulators of the estrous cycle, pointing out their effects and differences and providing information for the creation of new efficient protocols for induction of estrus in those animals.

Single injection of eCG/hCG leads to successful estrous synchronization in the collared peccary (Pecari tajacu Linnaeus, 1758).

The establishment of protocols for the control of the ovarian function of collared peccaries is recommended for the development of assisted reproductive techniques. The goals were to (1) compare a gonadotropin combination with prostaglandin analogue to synchronize timing of onset of estrus among animals, and (2) elucidate the effects of the most desirable protocol for performing an artificial insemination study and macroscopic evaluation of the ovaries. Three of five females treated with a double administration of 120 µg prostaglandin (cloprostenol) at a 9-day interval expressed symptoms of estrus 9 days after the second injection. One female presented estrus after 6 days, whereas other did not respond to the treatment. All females (5/5) treated with a single dose containing 400 IU eCG and 200 IU hCG manifested estrus 6 days after the hormone injection. In a second experiment, ten females that were estrous synchronized using eCG/hCG, were artificially inseminated with fresh semen and monitored for pregnancy every 30 days. Although there was no detection of fetuses by ultrasonic examination, seven females (7/10) had greater than basal progesterone values for 60 days after the treatments were imposed. Ovaries from two females treated with eCG/hCG were collected 6 days post-injection. There was confirmation of an ovarian stimulation as a result of the presence of 88 and 25 antral follicles, as well as three and eight hemorrhagic structures in ovaries of each female, respectively. It, therefore, is proposed that eCG/hCG can be used as an effective treatment for estrous synchronization in collared peccaries.

Sistemas de inseminação artificial em dois dias com observação de estro ou em tempo fixo para vacas de corte amamentando / Artificial insemination systems within two days of estrus detection or at fixed time for suckled beef cows

O objetivo do presente experimento foi investigar se a realização exclusiva da inseminação artificial em tempo fixo (IATF), empregando como indutor da ovulação o benzoato de estradiol (BE), proporciona taxas de prenhez semelhantes a uma associação de IA convencional e IATF com GnRH, em vacas de corte no pós-parto. Duzentos e cinqüenta vacas amamentado receberam um pessário vaginal contendo 250mg de acetato de medroxi-progesterona (MAP) e uma injeção intramuscular (IM) de 5mg de BE no dia 0. O pessário vaginal permaneceu por sete dias. No dia 6, foram aplicadas 400UI de gonadotrofina coriônica eqüina por via IM e 5mg de análogo de prostaglandina na submucosa vulvar, realizando nesse momento o desmame por 96h. Após a retirada dos pessários (dia 7), as vacas foram distribuídas em dois grupos. No grupo BioRep (n=150), as fêmeas foram observadas duas vezes por dia para detecção de estro por 48h e inseminadas 12h após sua manifestação. Os animais que não manifestaram estro nesse período receberam uma injeção IM de 100mg de GnRH, sendo submetidas à IATF, 16 a 18h após. No grupo BE (n=100), as vacas receberam uma injeção de 1mg de BE IM no dia 8 e foram inseminadas em tempo fixo no dia 9. A porcentagem de prenhez no grupo BioRep (54,7 por cento) foi maior (P<0,01) do que no grupo BE (33,3 por cento). Em vaca amamentando, a observação de estro por dois dias associada à IATF, utilizando GnRH para induzir a ovulação, proporcionou taxas de prenhez superiores ao uso exclusivo de IATF com BE.

This experiment was aimed at comparing two estrus induction protocols for cows in post partum period, using either GnRH and two-day artificial insemination (AI) or estradiol benzoate (EB) and fixed-time artificial insemination (TAI). A total of 250 suckled beef cows received a vaginal device containing 250mg of medroxyprogesterone acetate (MPA) and an injection of 5mg of EB intramuscularly (IM) on day 0. The vaginal device was removed on day 7. On day 6, cows were injected with 400IU eCG (IM) and 5mg prostaglandin analog (into vulvar submucosa) and calves were removed for 96 hours (h). After removing the vaginal devices (day 7), cows were divided in two groups. In the BioRep group (n=150), estrus detection was carried out twice a day during 48h and the animals were inseminated 12h after detection. Cows which were not detected in estrus received 100mg of GnRH IM and were inseminated 16 to 18h later. In EB group, cows were injected IM with 1mg of EB on day 8 and were inseminated on day 9 without estrus detection. The pregnancy rate was higher (P<0.01) in the BioRep group (54.7 percent) than in the EB group (33.3 percent). In suckled cows, two days of estrus detection associated to fixed-time insemination using GnRH to induce ovulation allowed the attainment of higher pregnancies rates than exclusively TAI using EB.

Sistemas de inseminação artificial em dois dias com observação de estro ou em tempo fixo para vacas de corte amamentando / Artificial insemination systems within two days of estrus detection or at fixed time for suckled beef cows

O objetivo do presente experimento foi investigar se a realização exclusiva da inseminação artificial em tempo fixo (IATF), empregando como indutor da ovulação o benzoato de estradiol (BE), proporciona taxas de prenhez semelhantes a uma associação de IA convencional e IATF com GnRH, em vacas de corte no pós-parto. Duzentos e cinqüenta vacas amamentado receberam um pessário vaginal contendo 250mg de acetato de medroxi-progesterona (MAP) e uma injeção intramuscular (IM) de 5mg de BE no dia 0. O pessário vaginal permaneceu por sete dias. No dia 6, foram aplicadas 400UI de gonadotrofina coriônica eqüina por via IM e 5mg de análogo de prostaglandina na submucosa vulvar, realizando nesse momento o desmame por 96h. Após a retirada dos pessários (dia 7), as vacas foram distribuídas em dois grupos. No grupo BioRep (n=150), as fêmeas foram observadas duas vezes por dia para detecção de estro por 48h e inseminadas 12h após sua manifestação. Os animais que não manifestaram estro nesse período receberam uma injeção IM de 100mg de GnRH, sendo submetidas à IATF, 16 a 18h após. No grupo BE (n=100), as vacas receberam uma injeção de 1mg de BE IM no dia 8 e foram inseminadas em tempo fixo no dia 9. A porcentagem de prenhez no grupo BioRep (54,7 por cento) foi maior (P<0,01) do que no grupo BE (33,3 por cento). Em vaca amamentando, a observação de estro por dois dias associada à IATF, utilizando GnRH para induzir a ovulação, proporcionou taxas de prenhez superiores ao uso exclusivo de IATF com BE.(AU)

This experiment was aimed at comparing two estrus induction protocols for cows in post partum period, using either GnRH and two-day artificial insemination (AI) or estradiol benzoate (EB) and fixed-time artificial insemination (TAI). A total of 250 suckled beef cows received a vaginal device containing 250mg of medroxyprogesterone acetate (MPA) and an injection of 5mg of EB intramuscularly (IM) on day 0. The vaginal device was removed on day 7. On day 6, cows were injected with 400IU eCG (IM) and 5mg prostaglandin analog (into vulvar submucosa) and calves were removed for 96 hours (h). After removing the vaginal devices (day 7), cows were divided in two groups. In the BioRep group (n=150), estrus detection was carried out twice a day during 48h and the animals were inseminated 12h after detection. Cows which were not detected in estrus received 100mg of GnRH IM and were inseminated 16 to 18h later. In EB group, cows were injected IM with 1mg of EB on day 8 and were inseminated on day 9 without estrus detection. The pregnancy rate was higher (P<0.01) in the BioRep group (54.7 percent) than in the EB group (33.3 percent). In suckled cows, two days of estrus detection associated to fixed-time insemination using GnRH to induce ovulation allowed the attainment of higher pregnancies rates than exclusively TAI using EB.(AU)

Efeito da somatotrofina bovina (bST-r), do implante de progestágeno e do desmame por 72 horas na indução do estro e na taxa de prenhez em vacas

This study aimed to assess the efficiency of hormonal treatment in the postpartum fertility of nursing beef cows. Seventy-three cows (Hereford x Nellore) raised extensively, with body condition ranging from 2 to 4 were randomly allotted in three groups. The GSED group, with 25 cows, received an intravaginal device (ID) of 250mg of medroxiprogesteron acetate and 500mg of recombinant bovine somatotropin (bST-r; day 0). After the ID withdrawal (day 7), the cows received 0.5mg of estradiol cipionate; their calves were temporarily weaned for 72 hours. In the SED group, 25 cows received a similar treatment, however, somatotropin was not used. In the control group, 23 cows were temporarily separated from their calves for 72 hours and did not receive any hormonal treatment. The cows were put together with the bulls for 30 days just after ID withdrawal. The cows were weighted and assessed for body condition at day 0 and just after bulls withdrawal. The cows lost weight in an average of 0.648 kg/day, and 56.5%, 33.3%, and 26.1% of estrous rates were observed, respectively for the GSED, SED and control groups (GSED vs. SED, P=0.0001; GSED vs. control, P=0.0007; SED vs. control, P=0.53). The pregnancy rates were 21.7%, 8.3%, and 13.0%, respectively for the GSED, SED and control groups (P=0.16). The results showed that the hormonal program associated with temporary 72-hour calf removal did not increase conception rate of cows that loosed weight from 50 to 70 days postpartum.

Este trabalho teve por objetivo avaliar a eficiência de tratamentos hormonais sobre a fertilidade de vacas de corte no pós-parto com diferentes condições corporais, durante a estação de monta de outono. Setenta e três vacas pluríparas cruzadas (Hereford x Nelore) criadas extensivamente, com condição corporal entre 2 e 4, foram pesadas e distribuídas em três grupos experimentais. O grupo GSED, constituído por 25 vacas, recebeu pessário vaginal (dia 0) contendo 250mg de acetato de medroxiprogesterona e 500mg de somatotropina bovina recombinante (bST-r). Na retirada dos pessários (dia 7), as vacas receberam 0,5mg de cipionato de estradiol e procedeu-se o desmame temporário dos bezerros por 72 horas. No grupo SED, 25 vacas receberam tratamento semelhante ao grupo GSED, porém não receberam bST-r. No grupo-controle, as 23 vacas somente foram separadas dos seus bezerros por 72h. Quando da retirada dos pessários as vacas foram colocadas com touros por 30 dias. Os animais foram pesados e avaliados quanto à condição corporal no início do experimento e na retirada dos touros (dia 37). Foi constatada perda média de peso de 0,648 kg/dia e os percentuais de estro foram de 26,1%, 33,3% e 56,5%, respectivamente, para os grupos controle, SED e GSED. O diagnóstico de gestação, realizado pela palpação retal 60 dias após a retirada dos touros, indicou percentuais de prenhez de 13,0%, 8,3% e 21,7%, respectivamente, para os grupos controle, SED e GSED (P=0,16), demonstrando que os programas hormonais adotados não foram eficientes no incremento das taxas de prenhez de vacas que perdiam peso entre 50 e 70 dias após o parto.

Effect of the association between GnRH, PGF2a and calf removal on the return to cycllcity of nelore cows in post-partum anestrous / Efeito da associação entre GnRH, PGF2a e desmame temporário sobre o restabelecimento da ciclicidade de vacas Nelore em anestro pós-parto

The objective was to test the efficiency of the association between GnRH, PGFp and temporary calf removal on the return to ciclicity. One hundred and fifty Nelore cows with calf on foot were randomly and equally alloted into different experimental groups and artificially inseminated (AI) 12 hours alter standing estrous, detected by teasers and visual observation. The females were initially treated with 0.25 mg of gonadorelin (G) or with 0.02 rng of buserelin (B) associating (C) or not (S) with temporary calf removal of 48 hours. The females that associated did not respond to one of these treatments in the interval of 14 days, received 0.25 mg of cloprostenol at the 15th day, with observation of estrous for more 120 hours. Alter administration of both GnRH, 30.0% (G+CDT), 20.0% (G+SDT), 40.0% (B+CDT) and 23.3% (B+SDT) exhibited estrous, with no difference observed between the groups. From the females that received cloprostenol, 40.0% (G+CDT), 29.2% (G+SDT), 77.8% (B+CDT) and 34.8% (B+SDT) responded to the treatment within 120 hours, with no difference observed among the groups. From ali the females treated with this estrous induction program, 73.3% (G+CDT), 43.3% (G+SDT), 86.7% (B+CDT), 50.0% (B+SDT) and 30.0% (Control) exhibited estrous in a period of 20 days, showing that the percentages of groups G+CDT and B+GDT were higher (P s 0,05) than the Control group, and that those 01

Objetivou-se testar a eficiência da associação entre GnRH, PGFp e desmame temporário sobre o restabelecimento da ciclicidade de vacas Nelore em anestro pós-parto. Foram utilizadas 150 fêmeas com cria ao pé, as quais foram aleatoriamente e equitativamente distribuídas em cinco grupos experimentais e artificialmente inseminadas (IA) após 12 horas do início do estro, detectado por rufiões e observação visual. As fêmeas foram inicialmente tratadas com 0,25 mg de gonadorelina (G) ou com 0,02 mg de buserelina (B) associando-se (C) ou não (S) o desmame temporário (DT) de 48 horas. As fêmeas que não responderam ao tratamento no período de 14 dias, receberam 0,25 mg de cloprostenol na submucosa vulvar no 150 dia, observando-se o estro por mais 120 horas. Após a administração de ambos os GnRH, 30,0% (G+CDT), 20,0% (G+SDT), 40,0% (B+CDT) e 23,3% (B+SDT) apresentaram estro, não se constatando diferença entre os grupos. Das fêmeas que receberam o cloprostenol, 40,0% (G+CDT), 29,2% (G+SDT), 77,8% (B+CDT) e 34,8% (B+SDT) responderam ao tratamento em 120 horas, não se registrando também diferença entre os grupos. De todas as fêmeas tratadas, 73,3% (G+CDT), 43,3% (G+SDT), 86,7% (B+CDT), 50,0% (B+SDT) e 30,0% (Controle) apresentaram estro no período de 20 dias, verificando-se que as porcentagens dos grupos G+CDT e B+CDT foram maiores (P :5 0,05) do que a do grupo Controle e que as dos grupos G+S

Effect of the association between GnRH, PGF2a and calf removal on the return to cycllcity of nelore cows in post-partum anestrous / Efeito da associação entre GnRH, PGF2a e desmame temporário sobre o restabelecimento da ciclicidade de vacas Nelore em anestro pós-parto

The objective was to test the efficiency of the association between GnRH, PGFp and temporary calf removal on the return to ciclicity. One hundred and fifty Nelore cows with calf on foot were randomly and equally alloted into different experimental groups and artificially inseminated (AI) 12 hours alter standing estrous, detected by teasers and visual observation. The females were initially treated with 0.25 mg of gonadorelin (G) or with 0.02 rng of buserelin (B) associating (C) or not (S) with temporary calf removal of 48 hours. The females that associated did not respond to one of these treatments in the interval of 14 days, received 0.25 mg of cloprostenol at the 15th day, with observation of estrous for more 120 hours. Alter administration of both GnRH, 30.0% (G+CDT), 20.0% (G+SDT), 40.0% (B+CDT) and 23.3% (B+SDT) exhibited estrous, with no difference observed between the groups. From the females that received cloprostenol, 40.0% (G+CDT), 29.2% (G+SDT), 77.8% (B+CDT) and 34.8% (B+SDT) responded to the treatment within 120 hours, with no difference observed among the groups. From ali the females treated with this estrous induction program, 73.3% (G+CDT), 43.3% (G+SDT), 86.7% (B+CDT), 50.0% (B+SDT) and 30.0% (Control) exhibited estrous in a period of 20 days, showing that the percentages of groups G+CDT and B+GDT were higher (P s 0,05) than the Control group, and that those 01

Objetivou-se testar a eficiência da associação entre GnRH, PGFp e desmame temporário sobre o restabelecimento da ciclicidade de vacas Nelore em anestro pós-parto. Foram utilizadas 150 fêmeas com cria ao pé, as quais foram aleatoriamente e equitativamente distribuídas em cinco grupos experimentais e artificialmente inseminadas (IA) após 12 horas do início do estro, detectado por rufiões e observação visual. As fêmeas foram inicialmente tratadas com 0,25 mg de gonadorelina (G) ou com 0,02 mg de buserelina (B) associando-se (C) ou não (S) o desmame temporário (DT) de 48 horas. As fêmeas que não responderam ao tratamento no período de 14 dias, receberam 0,25 mg de cloprostenol na submucosa vulvar no 150 dia, observando-se o estro por mais 120 horas. Após a administração de ambos os GnRH, 30,0% (G+CDT), 20,0% (G+SDT), 40,0% (B+CDT) e 23,3% (B+SDT) apresentaram estro, não se constatando diferença entre os grupos. Das fêmeas que receberam o cloprostenol, 40,0% (G+CDT), 29,2% (G+SDT), 77,8% (B+CDT) e 34,8% (B+SDT) responderam ao tratamento em 120 horas, não se registrando também diferença entre os grupos. De todas as fêmeas tratadas, 73,3% (G+CDT), 43,3% (G+SDT), 86,7% (B+CDT), 50,0% (B+SDT) e 30,0% (Controle) apresentaram estro no período de 20 dias, verificando-se que as porcentagens dos grupos G+CDT e B+CDT foram maiores (P :5 0,05) do que a do grupo Controle e que as dos grupos G+S