RESUMO

Paternal programming is the concept that the environmental signals from the sire's experiences leading up to mating can alter semen and ultimately affect the phenotype of resulting offspring. Potential mechanisms carrying the paternal effects to offspring can be associated with epigenetic signatures (DNA methylation, histone modification and non-coding RNAs), oxidative stress, cytokines, and the seminal microbiome. Several opportunities exist for sperm/semen to be influenced during development; these opportunities are within the testicle, the epididymis, or accessory sex glands. Epigenetic signatures of sperm can be impacted during the pre-natal and pre-pubertal periods, during sexual maturity and with advancing sire age. Sperm are susceptible to alterations as dictated by their developmental stage at the time of the perturbation, and sperm and seminal plasma likely have both dependent and independent effects on offspring. Research using rodent models has revealed that many factors including over/under nutrition, dietary fat, protein, and ingredient composition (e.g., macro- or micronutrients), stress, exercise, and exposure to drugs, alcohol, and endocrine disruptors all elicit paternal programming responses that are evident in offspring phenotype. Research using livestock species has also revealed that sire age, fertility level, plane of nutrition, and heat stress can induce alterations in the epigenetic, oxidative stress, cytokine, and microbiome profiles of sperm and/or seminal plasma. In addition, recent findings in pigs, sheep, and cattle have indicated programming effects in blastocysts post-fertilization with some continuing into post-natal life of the offspring. Our research group is focused on understanding the effects of common management scenarios of plane of nutrition and growth rates in bulls and rams on mechanisms resulting in paternal programming and subsequent offspring outcomes. Understanding the implication of paternal programming is imperative as short-term feeding and management decisions have the potential to impact productivity and profitability of our herds for generations to come.(AU)

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RESUMO

Currently, gonadotropin products (follicle stimulating hormone, FSH, and luteinizing hormone, LH) used in animal reproduction are produced by extraction and purification from abattoir-derived pituitary glands. This method, relying on animal-derived materials, carries the potential risk of hormone contamination and pathogen transmission. Additionally, chorionic gonadotropins are extracted from the blood of pregnant mares (equine chorionic gonadotropin; eCG) or the urine of pregnant women (human chorionic gonadotropin; hCG). However, recent advancements have introduced recombinant gonadotropins for assisted animal reproduction therapies. The traditional use of FSH for superovulation has limitations, including labor requirements and variability in superovulation response, affecting the success of in vivo (SOV) and in vitro (OPU/IVEP) embryo production. FSH treatment for superstimulation before OPU can promote the growth of a homogenous follicular population and the recovery of competent oocytes suitable for IVEP procedures. At present, a single injection of a preparation of long-acting bovine recombinant FSH (rFSH) produced similar superovulation responses resulting in the production of good-quality in vivo and in vitro embryos. Furthermore, the treatment with eCG at FTAI protocol has demonstrated its efficacy in promoting follicular growth, ovulation, and P/AI, mainly in heifers and anestrous cows. Currently, treatment with recombinant glycoproteins with eCG-like activity (r-eCG) have shown promising results in increasing follicular growth, ovulation, and P/AI in cows submitted to P4/E2 -based protocols. Bovine somatotropin (bST) is a naturally occurring hormone found in cows. Recombinant bovine somatotropin (rbST), produced through genetic engineering techniques, has shown potential in enhancing reproductive outcomes in ruminants. Treatment with rbST has been found to improve P/IA, increase donor embryo production, and enhance P/ET in recipients. The use of recombinant hormones allows to produce non-animal-derived products, offering several advantages in assisted reproductive technologies for ruminants. This advancement opens up new possibilities for improving reproductive efficiency and success rates in the field of animal reproduction.(AU)

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RESUMO

This review focuses on the innate immune events modulated by conceptus signaling during early pregnancy in ruminants. Interferon-tau (IFN-) plays a role in the recognition of pregnancy in ruminants, which involves more than the inhibition of luteolytic pulses of PGF2 to maintain corpus luteum function. For successful pregnancy establishment, the allogenic conceptus needs to prevent rejection by the female. Therefore, IFN- exerts paracrine and endocrine actions to regulate the innate immune system and prevent conceptus rejection. Additionally, other immune regulators work in parallel with IFN-, such as the pattern recognition receptors (PRR). These receptors are activated during viral and bacterial infections and in early pregnancy, but it remains unknown whether PPR expression and function are controlled by IFN-. Therefore, this review focuses on the main components of the innate immune response that are involved with early pregnancy and their importance to avoid conceptus rejection.(AU)

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RESUMO

Background: Fetal attachments, placentation and embryonic development have been widely discussed in rodents such as agoutisand cavies, as well as research on glycosaminoglycans (GAGs) in rats and rabbits. Moreover, studies on buffalo, cattle and sheep aredescribed in ruminants, and work has also been reported in sheep with GAGs in placentoma. However, further studies are needed inthis regard, since there are reports of economic losses associated with reproductive failures described for cattle such as changes in thechorion and allantois, and in sheep in which changes between the transition from vitelline to allantois circulation have been discussed.Review: In relation to embryonic development, detailed studies have been described in rodents such as rats (12 days old), desertmouse (15 days old) and agoutis at 30 days. Macroscopic structures such as the cephalic region, nose, optic vesicle, cervical curvature, thoracic and pelvic limbs were observed, as well as microscopic structures such as the pituitary, lung, heart, brain cavity, liver,retina, and ossification regions. There are reports of buffalo and cattle studies in ruminants describing early embryonic development.However, the research in the case of sheep is limited, meaning there is only the ultrasound examination, such as gestational diagnosisand morphometric measurement of the embryonic vesicle. Still, studies with umbilical funicular and placental development of sheepwith different gestational ages can be highlighted. Regarding extraembryonic annexes, four important structures which contributeto embryonic maintenance have been reported. These are called the chorion, amnion, allantois and yolk sac, respectively, and areresponsible for originating the placenta, embryonic protection, collecting metabolic waste and early embryonic nutrition. In...(AU)

Assuntos

RESUMO

Background: Fetal attachments, placentation and embryonic development have been widely discussed in rodents such as agoutisand cavies, as well as research on glycosaminoglycans (GAGs) in rats and rabbits. Moreover, studies on buffalo, cattle and sheep aredescribed in ruminants, and work has also been reported in sheep with GAGs in placentoma. However, further studies are needed inthis regard, since there are reports of economic losses associated with reproductive failures described for cattle such as changes in thechorion and allantois, and in sheep in which changes between the transition from vitelline to allantois circulation have been discussed.Review: In relation to embryonic development, detailed studies have been described in rodents such as rats (12 days old), desertmouse (15 days old) and agoutis at 30 days. Macroscopic structures such as the cephalic region, nose, optic vesicle, cervical curvature, thoracic and pelvic limbs were observed, as well as microscopic structures such as the pituitary, lung, heart, brain cavity, liver,retina, and ossification regions. There are reports of buffalo and cattle studies in ruminants describing early embryonic development.However, the research in the case of sheep is limited, meaning there is only the ultrasound examination, such as gestational diagnosisand morphometric measurement of the embryonic vesicle. Still, studies with umbilical funicular and placental development of sheepwith different gestational ages can be highlighted. Regarding extraembryonic annexes, four important structures which contributeto embryonic maintenance have been reported. These are called the chorion, amnion, allantois and yolk sac, respectively, and areresponsible for originating the placenta, embryonic protection, collecting metabolic waste and early embryonic nutrition. In...

Assuntos

RESUMO

O cultivo in vitro de folículos (CIVF), também conhecido como Ovário Artificial, representa uma excelente ferramenta para aumentar nossa compreensão a respeito do controle da foliculogênese inicial, que é crucial para otimizar o uso futuro de um grande número de oócitos imaturos inclusos em folículos pré-antrais (FPs) (principalreserva ovariana) em técnicas de reprodução assistida em humanos, bem como em outras espécies de mamíferos, incluindo os ruminantes. Até o momento, os melhores resultados de CIVF foram relatados em camundongos com a produção de crias vivas a partir de folículos primordiais cultivados in vitro. No entanto, em outras espécies como os ruminantes, esses resultados têm se limitado à produção de um número variável de oócitos maturos e baixas porcentagens de embriões após o cultivo in vitro de folículos pré-antrais secundários tardios isolados de ovários de cabras, búfalas e ovelhas. A presente revisão apresenta e discute os principais achados, limitações e perspectivas da foliculogênese in vitro em ruminantes com foco nas espécies bovinas, caprinas e ovinas.(AU)

The in vitro follicle culture (IVFC), also known as artificial ovary, represents an outstanding tool to increase our understanding of the control of early folliculogenesis which is crucial to optimize the future use of a large, number of immature oocytes enclosed in preantral follicles (PFs) (main ovarian reserve) in assisted reproductive techniques in humans as well as in others mammalian species including the ruminants. To date, the best results of IVFC were reported from mice with the production of live offspring from primordial follicles cultured in vitro. However, in other ruminant species, these results have been limited to the production of a variable number of mature oocytes and low percentages of embryos after in vitro culture of goat, buffalo and sheep isolated late secondary preantral follicles. The present review presents and discusses the main findings, limitations, and prospects of in vitro folliculogenesis in ruminants focusing on bovine, caprine, and ovine species.(AU)

Assuntos

RESUMO

The use of ACP® as a means of maintenance in the stages of multiple ovulation and embryo transfer, has not yet been reported in the literature, although ACP® is a plant fluid rich in nutrients. Thus, the objective was to compare the efficiency of ACP® as a substitute for embryo maintenance medium during MOTE biotechnology in goats and sheep. For this, three donor goats, Anglo-Nubian breed and three donor sheep, Dorper breed were used. Fifteen recipient females of each species were used. The donors were submitted to the superovulation protocol and inseminated, and later the embryos were collected. After harvesting, the embryos were submitted to the control maintenance medium, TQC Holding® or ACP® maintenance medium. The recipients were synchronized simultaneously with the donors, and after 30 days the pregnancy diagnosis was made. It was obtained 10% of pregnant in goats and 75% of pregnant in sheep, whose embryos were submitted to the ACP® maintenance medium before the innovation. It is concluded that the means of maintenance of ACP® embryos did not negatively influence the embryonic quality and the development of pregnancy in small ruminants.(AU)

Assuntos

RESUMO

The objective was to evaluate the maturation rates of goat oocytes submitted to slow freezing in conventional medium for IVM. For this purpose, cumulus-oocyte complexes aspirated from pubic goat ovaries were classified morphologically and slowly frozen with 1.5 M ethylene glycol. After thawing the cryopreserved oocytes, those classified as viable were matured in conventional in vitro maturation medium. Evaluating the maturation rate, the percentage of matured oocytes in the group that underwent the cryopreservation process is significantly lower (17.6%) when compared to the control group (69.2%), also showing a high percentage of immature oocytes. Several oocyte injuries were found, caused by the studied cryopreservation method, interfering with their oocyte competence. Even with nuclear maturation rates, observed through the extrusion of the first polar corpuscle, the morphologies were altered in most oocytes, and further studies using new techniques and / or other cryoprotectants are necessary.(AU)

Assuntos

RESUMO

Em decorrência da necessidade de aproveitamento de matrizes e reprodutores de alto mérito genético biotecnologias reprodutivas como a Multipla Ovulação e Transferência de Embriões (MOTE) vêm sendo cada vez mais utilizada, garantindo assim a produtividade mesmo diante de obstáculos. Nos últimos anos essa atividade vem apresentando um acentuado desenvolvimento e aprimoramento, principalmente em caprinos e ovinos que se constituem espécies de extrema importância para a Região Nordeste do Brasil, por serem uma das culturas mais vantajosas quando comparado com as demais culturas como a pecuária e por se tratar de uma atividade sustentável do ponto de vista ambiental, sociocultural e econômico. Dentre os principais fatores que ainda afetam o desempenho e sucesso dos programas de Transferência de Embriões (TE) em pequenos ruminantes podemos destacar a seleção de fêmeas doadoras e receptoras, variabilidade de resposta aos protocolos de superovulação, regressão prematura de corpo lúteo (CL), necessidade de etapas cirúrgicas como a laparotomia e laparoscopia e baixa disponibilidade de mão de obra especializada. Nesse sentido, este artigo aborda as principais etapas da produção in vivo de embriões em pequenos ruminantes bem como os desafios e as perspectivas de cada etapa a serem enfrentadas na Região Nordeste do Brasil.(AU)

As a result of the need to use matrices and breeders with high genetic merit, reproductive biotechnologies such as Multiple Ovulation and Embryo Transfer (MOTE) have been increasingly used, thus guaranteeing productivity even in the face of obstacles. In recent years, this activity has shown a marked development and improvement, especially in goats and sheep, which are extremely important species for the Northeast Region of Brazil, as they are one of the most advantageous crops for this region when compared to other crops such as livestock and because it is a sustainable activity from an environmental, socio-cultural and economic point of view. Among the main factors that still affect the performance and success of Embryo Transfer (ET) programs in small ruminants we can highlight the selection of donor and recipient females, variability in response to superovulation protocols, premature corpus luteum (CL) regression, need for surgical steps such as laparotomy and laparoscopy and low availability of specialized labor. In this sense, this article addresses the main stages of invivo embryo production in small ruminants as well as the challenges and perspectives of each stage to be faced in the Northeast Region of Brazil.(AU)

Assuntos

RESUMO

Em decorrência da necessidade de aproveitamento de matrizes e reprodutores de alto mérito genético biotecnologias reprodutivas como a Multipla Ovulação e Transferência de Embriões (MOTE) vêm sendo cada vez mais utilizada, garantindo assim a produtividade mesmo diante de obstáculos. Nos últimos anos essa atividade vem apresentando um acentuado desenvolvimento e aprimoramento, principalmente em caprinos e ovinos que se constituem espécies de extrema importância para a Região Nordeste do Brasil, por serem uma das culturas mais vantajosas quando comparado com as demais culturas como a pecuária e por se tratar de uma atividade sustentável do ponto de vista ambiental, sociocultural e econômico. Dentre os principais fatores que ainda afetam o desempenho e sucesso dos programas de Transferência de Embriões (TE) em pequenos ruminantes podemos destacar a seleção de fêmeas doadoras e receptoras, variabilidade de resposta aos protocolos de superovulação, regressão prematura de corpo lúteo (CL), necessidade de etapas cirúrgicas como a laparotomia e laparoscopia e baixa disponibilidade de mão de obra especializada. Nesse sentido, este artigo aborda as principais etapas da produção in vivo de embriões em pequenos ruminantes bem como os desafios e as perspectivas de cada etapa a serem enfrentadas na Região Nordeste do Brasil.

As a result of the need to use matrices and breeders with high genetic merit, reproductive biotechnologies such as Multiple Ovulation and Embryo Transfer (MOTE) have been increasingly used, thus guaranteeing productivity even in the face of obstacles. In recent years, this activity has shown a marked development and improvement, especially in goats and sheep, which are extremely important species for the Northeast Region of Brazil, as they are one of the most advantageous crops for this region when compared to other crops such as livestock and because it is a sustainable activity from an environmental, socio-cultural and economic point of view. Among the main factors that still affect the performance and success of Embryo Transfer (ET) programs in small ruminants we can highlight the selection of donor and recipient females, variability in response to superovulation protocols, premature corpus luteum (CL) regression, need for surgical steps such as laparotomy and laparoscopy and low availability of specialized labor. In this sense, this article addresses the main stages of invivo embryo production in small ruminants as well as the challenges and perspectives of each stage to be faced in the Northeast Region of Brazil.

Assuntos

RESUMO

O cultivo in vitro de folículos (CIVF), também conhecido como Ovário Artificial, representa uma excelente ferramenta para aumentar nossa compreensão a respeito do controle da foliculogênese inicial, que é crucial para otimizar o uso futuro de um grande número de oócitos imaturos inclusos em folículos pré-antrais (FPs) (principalreserva ovariana) em técnicas de reprodução assistida em humanos, bem como em outras espécies de mamíferos, incluindo os ruminantes. Até o momento, os melhores resultados de CIVF foram relatados em camundongos com a produção de crias vivas a partir de folículos primordiais cultivados in vitro. No entanto, em outras espécies como os ruminantes, esses resultados têm se limitado à produção de um número variável de oócitos maturos e baixas porcentagens de embriões após o cultivo in vitro de folículos pré-antrais secundários tardios isolados de ovários de cabras, búfalas e ovelhas. A presente revisão apresenta e discute os principais achados, limitações e perspectivas da foliculogênese in vitro em ruminantes com foco nas espécies bovinas, caprinas e ovinas.

The in vitro follicle culture (IVFC), also known as artificial ovary, represents an outstanding tool to increase our understanding of the control of early folliculogenesis which is crucial to optimize the future use of a large, number of immature oocytes enclosed in preantral follicles (PFs) (main ovarian reserve) in assisted reproductive techniques in humans as well as in others mammalian species including the ruminants. To date, the best results of IVFC were reported from mice with the production of live offspring from primordial follicles cultured in vitro. However, in other ruminant species, these results have been limited to the production of a variable number of mature oocytes and low percentages of embryos after in vitro culture of goat, buffalo and sheep isolated late secondary preantral follicles. The present review presents and discusses the main findings, limitations, and prospects of in vitro folliculogenesis in ruminants focusing on bovine, caprine, and ovine species.

Assuntos

RESUMO

The use of ACP® as a means of maintenance in the stages of multiple ovulation and embryo transfer, has not yet been reported in the literature, although ACP® is a plant fluid rich in nutrients. Thus, the objective was to compare the efficiency of ACP® as a substitute for embryo maintenance medium during MOTE biotechnology in goats and sheep. For this, three donor goats, Anglo-Nubian breed and three donor sheep, Dorper breed were used. Fifteen recipient females of each species were used. The donors were submitted to the superovulation protocol and inseminated, and later the embryos were collected. After harvesting, the embryos were submitted to the control maintenance medium, TQC Holding® or ACP® maintenance medium. The recipients were synchronized simultaneously with the donors, and after 30 days the pregnancy diagnosis was made. It was obtained 10% of pregnant in goats and 75% of pregnant in sheep, whose embryos were submitted to the ACP® maintenance medium before the innovation. It is concluded that the means of maintenance of ACP® embryos did not negatively influence the embryonic quality and the development of pregnancy in small ruminants.

Assuntos

RESUMO

The objective was to evaluate the maturation rates of goat oocytes submitted to slow freezing in conventional medium for IVM. For this purpose, cumulus-oocyte complexes aspirated from pubic goat ovaries were classified morphologically and slowly frozen with 1.5 M ethylene glycol. After thawing the cryopreserved oocytes, those classified as viable were matured in conventional in vitro maturation medium. Evaluating the maturation rate, the percentage of matured oocytes in the group that underwent the cryopreservation process is significantly lower (17.6%) when compared to the control group (69.2%), also showing a high percentage of immature oocytes. Several oocyte injuries were found, caused by the studied cryopreservation method, interfering with their oocyte competence. Even with nuclear maturation rates, observed through the extrusion of the first polar corpuscle, the morphologies were altered in most oocytes, and further studies using new techniques and / or other cryoprotectants are necessary.

Assuntos

RESUMO

Esta revisão reporta os recentes avanços da Inseminação Artificial em caprinos (IA) no Brasil nas últimas duas décadas. Estes avanços foram pautados primariamente no estudo e conhecimento dos eventos reprodutivos de cabras submetidas a diferentes formas de controle do ciclo estral e ovulação. Estas abordam principalmente o desenvolvimento e caracterização precisa de protocolos de indução e sincronização de estro em cabras durante a estação de anestro fisiológico e de acasalamento natural. Paralelamente, foi desenvolvida a Técnica Embrapa de IA cervical em caprinos por meio da imobilização cervical. Associadamente, os estudos caracterizaram a relação do muco cervical e o momento ideal para execução da IA com diferentes tipos de sêmen. Protótipos e um Kit de IA foram desenvolvidos e testados em condições de laboratório e de campo no âmbito do programa nacional de melhoramento genético de caprinos leiteiros – CapraGene®. Fatores que interferem na taxa de gestação após a IA foram identificados e classificados. Estudos com base em ultrassonografia transretal revelaram a prevalência de desordens reprodutivas caracterizando os principais problemas associados à subfertilidade ou infertilidade na cabra. Todos estes estudos permitiram consolidar uma das mais produtivas e aplicadas coleções de conhecimento sobre IA em caprinos dos últimos 20 anos no Brasil.

This review reports the advances of goat Artificial Insemination (AI) in Brazil in the last two decades. These advances were based primarily on the study and knowledge of the reproductive events of goats subjected to different methods of control of the estrous cycle and ovulation. These approaches are mainly related to the development and precise characterization of protocols of estrus induction and synchronization in goats during either the natural breeding or nonbreeding season. In parallel, the Embrapa Technique of cervical AI through cervical immobilization in goats was developed. In association, the studies characterized the cervical mucus and the ideal moment for AI execution with different types of semen. Prototypes and an AI kit were developed and tested at both laboratory and field conditions in the national dairy goat breeding program - CapraGene®. Factors affecting the pregnancy rate after AI were identified and classified. Studies based on transrectal ultrasonography have revealed the prevalence of reproductive disorders characterizing the major problems associated with subfertility or infertility in the goat. All these studies allowed to consolidate one of the most productive and applied collections of AI knowledge in goats of the last 20 years in Brazil.

Assuntos

RESUMO

A vitrificação é uma alternativa viável ao método de criopreservação clássica e consiste na utilização de altas concentrações de agente crioprotetores e rápida congelação, tendo como principal vantagem à não formação de cristais de gelo. Esta técnica é acessível por apresentar facilidade, rapidez e baixo custo para sua produção, não necessitando de grandes equipamentos, apresentando-se com grande potencial a ser explorado. Portanto, objetivouse com esta revisão descrever as principais características da vitrificação, bem como os resultados obtidos com sêmen de em caprinos e ovinos e as perspectivas para a utilização desta técnica.

Vitrification is a viable alternative to the classical cryopreservation method and consists in the use of high concentrations of cryoprotectants and fast freezing, having as the main advantage the absence of ice crystals formation. The feasibility of this technique is related to be easy, fast and with low cost of execution, since no expensive equipment is needed, presenting a high potential for investigation. Therefore, the objective of this review was to describe the characteristics of vitrification, as well as the results obtained with sheep and goat semen, and the perspectives for the adoption of this technique.

Assuntos

RESUMO

A biotécnica de múltipla ovulação e transferência de embriões (MOTE) em pequenos ruminantes tem aplicações que se estendem da pesquisa básica à aplicada. Porém, ainda existem etapas no processo da biotécnica que reduzem sua eficiência e restringem sua utilização, a exemplo da necessidade de procedimentos cirúrgicos. Em caprinos, já é possível realizar a MOTE sem nenhuma intervenção cirúrgica e com resultados satisfatórios. Todavia, em ovinos, as particularidades anatômicas da cérvix dificultam sua transposição, fazendo com que etapas cirúrgicas ainda sejam necessárias. Com foco nessa limitação, tem-se estudado e descrito técnicas para a dilatação cervical e métodos para triagem de doadoras de embrião com maior facilidade para transposição cervical. Assim, a colheita não cirúrgica, principalmente na espécie ovina, vem se tornando uma realidade exequível em condições de campo e pesquisa.

In small ruminants, the multiple ovulation and embryo transfer (MOET) has applications in basic and applied research. However, there are still drawbacks in this biotechnology hampering its applicability and efficiency, as the need of surgical intervention. In goats, it is possible to perform MOET without any surgical procedure and with satisfactory results. Although, in sheep, the anatomical features of the cervix make transcervical transposition challenging, leading to a wider use of surgical steps in this specie. In the attempt to overcome these limitations, techniques for cervical dilation and methods for screening donors with cervices that can be easily transposed have been studied and described. Therefore, the nonsurgical embryo collection, mainly in the ovine species, has become feasible under field and research conditions.

Assuntos

RESUMO

A vitrificação é uma alternativa viável ao método de criopreservação clássica e consiste na utilização de altas concentrações de agente crioprotetores e rápida congelação, tendo como principal vantagem à não formação de cristais de gelo. Esta técnica é acessível por apresentar facilidade, rapidez e baixo custo para sua produção, não necessitando de grandes equipamentos, apresentando-se com grande potencial a ser explorado. Portanto, objetivouse com esta revisão descrever as principais características da vitrificação, bem como os resultados obtidos com sêmen de em caprinos e ovinos e as perspectivas para a utilização desta técnica.(AU)

Vitrification is a viable alternative to the classical cryopreservation method and consists in the use of high concentrations of cryoprotectants and fast freezing, having as the main advantage the absence of ice crystals formation. The feasibility of this technique is related to be easy, fast and with low cost of execution, since no expensive equipment is needed, presenting a high potential for investigation. Therefore, the objective of this review was to describe the characteristics of vitrification, as well as the results obtained with sheep and goat semen, and the perspectives for the adoption of this technique.(AU)

Assuntos

RESUMO

A biotécnica de múltipla ovulação e transferência de embriões (MOTE) em pequenos ruminantes tem aplicações que se estendem da pesquisa básica à aplicada. Porém, ainda existem etapas no processo da biotécnica que reduzem sua eficiência e restringem sua utilização, a exemplo da necessidade de procedimentos cirúrgicos. Em caprinos, já é possível realizar a MOTE sem nenhuma intervenção cirúrgica e com resultados satisfatórios. Todavia, em ovinos, as particularidades anatômicas da cérvix dificultam sua transposição, fazendo com que etapas cirúrgicas ainda sejam necessárias. Com foco nessa limitação, tem-se estudado e descrito técnicas para a dilatação cervical e métodos para triagem de doadoras de embrião com maior facilidade para transposição cervical. Assim, a colheita não cirúrgica, principalmente na espécie ovina, vem se tornando uma realidade exequível em condições de campo e pesquisa.(AU)

In small ruminants, the multiple ovulation and embryo transfer (MOET) has applications in basic and applied research. However, there are still drawbacks in this biotechnology hampering its applicability and efficiency, as the need of surgical intervention. In goats, it is possible to perform MOET without any surgical procedure and with satisfactory results. Although, in sheep, the anatomical features of the cervix make transcervical transposition challenging, leading to a wider use of surgical steps in this specie. In the attempt to overcome these limitations, techniques for cervical dilation and methods for screening donors with cervices that can be easily transposed have been studied and described. Therefore, the nonsurgical embryo collection, mainly in the ovine species, has become feasible under field and research conditions.(AU)

Assuntos

RESUMO

Esta revisão reporta os recentes avanços da Inseminação Artificial em caprinos (IA) no Brasil nas últimas duas décadas. Estes avanços foram pautados primariamente no estudo e conhecimento dos eventos reprodutivos de cabras submetidas a diferentes formas de controle do ciclo estral e ovulação. Estas abordam principalmente o desenvolvimento e caracterização precisa de protocolos de indução e sincronização de estro em cabras durante a estação de anestro fisiológico e de acasalamento natural. Paralelamente, foi desenvolvida a Técnica Embrapa de IA cervical em caprinos por meio da imobilização cervical. Associadamente, os estudos caracterizaram a relação do muco cervical e o momento ideal para execução da IA com diferentes tipos de sêmen. Protótipos e um Kit de IA foram desenvolvidos e testados em condições de laboratório e de campo no âmbito do programa nacional de melhoramento genético de caprinos leiteiros CapraGene®. Fatores que interferem na taxa de gestação após a IA foram identificados e classificados. Estudos com base em ultrassonografia transretal revelaram a prevalência de desordens reprodutivas caracterizando os principais problemas associados à subfertilidade ou infertilidade na cabra. Todos estes estudos permitiram consolidar uma das mais produtivas e aplicadas coleções de conhecimento sobre IA em caprinos dos últimos 20 anos no Brasil.(AU)

This review reports the advances of goat Artificial Insemination (AI) in Brazil in the last two decades. These advances were based primarily on the study and knowledge of the reproductive events of goats subjected to different methods of control of the estrous cycle and ovulation. These approaches are mainly related to the development and precise characterization of protocols of estrus induction and synchronization in goats during either the natural breeding or nonbreeding season. In parallel, the Embrapa Technique of cervical AI through cervical immobilization in goats was developed. In association, the studies characterized the cervical mucus and the ideal moment for AI execution with different types of semen. Prototypes and an AI kit were developed and tested at both laboratory and field conditions in the national dairy goat breeding program - CapraGene®. Factors affecting the pregnancy rate after AI were identified and classified. Studies based on transrectal ultrasonography have revealed the prevalence of reproductive disorders characterizing the major problems associated with subfertility or infertility in the goat. All these studies allowed to consolidate one of the most productive and applied collections of AI knowledge in goats of the last 20 years in Brazil.(AU)

Assuntos

RESUMO

The in vitro follicle culture (IVFC) represents an outstanding tool to enhance our understanding of the control of folliculogenesis and to allow the future use of a large number of immature oocytes enclosed in preantral follicles (PFs) in assisted reproductive techniques in humans as well as in others mammalian species including the ruminants. So far, the best results of IVFC were reported from mice with the production of live offspring from primordial follicles cultured in vitro. Live birth has been obtained after the in vitro culture of bovine early antral follicles. However, in other ruminant species, these results have been limited to the production of a variable number of mature oocytes and low percentages of embryos after in vitro culture of goat, buffalo and sheep isolated secondary preantral follicles. The present review presents and discusses the main findings, limitations, and prospects of in vitro folliculogenesis in ruminants focusing on bovine, caprine, and ovine species.(AU)

Assuntos