RESUMO
The identification of mutations in the genes encoding bone morphogenetic protein 15 (BMP15) and growth and differentiation factor 9 (GDF9) associated with phenotypes of sterility or increased ovulation rate in sheep aroused interest in the study of the role of local factors in preantral and antral folliculogenesis in different species. An additive mutation in the BMP15 receptor, BMPR1b, which determines an increase in the ovulatory rate, has been introduced in several sheep breeds to increase the number of lambs born. Although these mutations indicate extremely relevant functions of these factors, the literature data on the regulation of the expression and function of these proteins and their receptors are very controversial, possibly due to differences in experimental models. The present review discusses the published data and preliminary results obtained by our group on the participation of local factors in the selection of the dominant follicle, ovulation, and follicular atresia in cattle, focusing on transforming growth factors beta and their receptors. The study of the expression pattern and the functionality of proteins produced by follicular cells and their receptors will allow increasing the knowledge about this local system, known to be involved in ovarian physiopathology and with the potential to promote contraception or increase the ovulation rate in mammals.(AU)
Assuntos
Animais , Feminino , Peptídeos e Proteínas de Sinalização Intercelular/análise , Proteína Morfogenética Óssea 15/análise , Folículo Ovariano/crescimento & desenvolvimento , Oócitos/químicaRESUMO
Estradiol cypionate (EC) or GnRH have been widely used for ovulation induction in timed embryo transfer (TET). EC administration increases the proportion of cows that show estrus, whereas GnRH promotes more synchronized ovulations. The aim of the present study was to evaluate the potential beneficial effects of combining EC and GnRH in TET. In experiment 1, no difference was observed on serum progesterone concentrations on Day 6 and 13 after GnRH treatment between GnRH and EC+GnRH groups. In experiment 2, pregnancy per embryo transfer (P/ET) did not differ (p = 0.69) between GnRH (62.8%) and EC+GnRH (58.7%) groups. In conclusion, combining EC and GnRH for ovulation induction does not increase progesterone secretion and pregnancy rate after TET in cattle.(AU)
Assuntos
Animais , Feminino , Gravidez , Indução da Ovulação/veterinária , Hormônio Liberador de Gonadotropina/análogos & derivados , Estradiol/análogos & derivados , Transferência Embrionária/instrumentaçãoRESUMO
Diversos hormônios podem ser utilizados em protocolos que visam otimizar biotécnicas reprodutivas como a inseminação artificial (IA) e inseminação artificial em tempo fixo (IATF), que exigem controle preciso do ciclo estral e da ovulação. Alguns hormônios possuem ação central no eixo hipotalâmico-hipofisário, como o hormônio liberador de gonadotrofinas (GnRH) e os ésteres de estradiolcomo o benzoato (BE) e o cipionato de estradiol (CE), enquanto outros como a gonadotrofina coriônica humana (hCG) e o hormônio luteinizante (LH) apresentam ação local, a nível ovariano. Atualmente os protocolos mais utilizados para indução da ovulação utilizam GnRH e estrógenos. Recentemente, foi demonstrado que as prostaglandinas possuem efeitos positivos na indução do processo ovulatório, mas seu mecanismo de ação não está totalmente esclarecido. A presente revisão tem por objetivo abordar os principais indutores da ovulação utilizados em protocolos para controle do ciclo estral em bovinos, relatando o período de ocorrência das ovulações após a sua aplicação.(AU)
Several hormones may be used in protocols aimed to optimize reproductive biotechniques such as artificial insemination (AI) and fixed-timed artificial insemination (FTAI) which require precise control of the estrous cycle and the ovulation. Some hormones act on the hypothalamic-pituitary axis, such as the gonadotrophin releasing hormone (GnRH) and estradiol esters such as estradiol benzoate (EB) and cypionate (EC), whereas others act directly on the ovaries, such as human chorionic gonadotrophin (hCG) and luteinizing hormone (LH). Currently, the most commonly used protocols for ovulation induction use GnRH or estrogen. Prostaglandins have recently been shown to have positive effects on induction of the ovulatory process, but their mechanism of action is not fully understood. The present review aims to address the main ovulation inducers used in protocols to control the estrous cycle in cattle, emphasizing the period between their administration and the occurrence of ovulation.(AU)
Assuntos
Animais , Feminino , Bovinos , Bovinos/fisiologia , Indução da Ovulação/métodos , Indução da Ovulação/veterinária , Hormônios Esteroides Gonadais/análiseRESUMO
A eficiência reprodutiva na bovinocultura é essencial para a produtividade e lucratividade do sistema. O ambiente uterino tem importância fundamental para o estabelecimento e manutenção da gestação em diferentes espécies e pode ser influenciado pela ação de diversos hormônios. Sabe-se que as concentrações fisiológicas de estrógeno possuem efeito sobre a imunidade, estrutura e funcionalidade uterina. Alguns autores utilizaram administrações de estrógeno, em doses isoladas, como profilaxia ou terapia em casos de infertilidade, entretanto, não foram observados efeitos benéficos ou até mesmo houve um aumento da contaminação bacteriana. Porém, outros estudos que utilizaram repetidas doses de estrógeno demonstraram efeitos positivos no desempenho reprodutivo em vacas repetidoras. Ainda, protocolos de inseminação artificial em tempo fixo (IATF) com suplementação de estrógeno ou com período prolongado de proestro têm possibilitado maiores taxas de prenhez e menos perdas gestacionais. Com base nisso, se faz necessário a realização de pesquisas que abordem o efeito do estrógeno sobre a fertilidade em condições controladas. O objetivo desta revisão é discutir aspectos relacionados a exposição ao estrógeno para prevenção ou terapia de transtornos reprodutivos com foco no ambiente uterino.
Reproductive efficiency in cattle is essential for the productivity and profitability of the system. The uterine environment has a fundamental importance for pregnancy establishment and maintenance in different species and can be influenced by the action of several hormones. It is well established that physiological concentrations of estrogen have effect on the uterine immunity, structure and functionality. Some authors evaluated estrogen administration, in single doses, for prophylaxis or therapy of infertility; however, no beneficial effects were observed, and, in some cases, there was an increase in bacterial contamination. Conversely, other studies using repeated doses of estrogen demonstrated positive effects on reproductive performance in repeat breeder cows. Furthermore, timedartificial insemination (TAI) protocols using estrogen or with prolonged proestrus are associated with increased pregnancy rates and seem to prevent pregnancy losses. Based on this, it is necessary to perform studies evaluating the effect of estrogen on fertility under controlled conditions. The objective of this review is to discuss aspects related to the exposure to estrogens to prevent or overcome reproductive disorders focusing on the uterine environment.
Assuntos
Feminino , Animais , Bovinos , Estrogênios/análise , Estrogênios/análogos & derivadosRESUMO
Diversos hormônios podem ser utilizados em protocolos que visam otimizar biotécnicas reprodutivas como a inseminação artificial (IA) e inseminação artificial em tempo fixo (IATF), que exigem controle preciso do ciclo estral e da ovulação. Alguns hormônios possuem ação central no eixo hipotalâmico-hipofisário, como o hormônio liberador de gonadotrofinas (GnRH) e os ésteres de estradiolcomo o benzoato (BE) e o cipionato de estradiol (CE), enquanto outros como a gonadotrofina coriônica humana (hCG) e o hormônio luteinizante (LH) apresentam ação local, a nível ovariano. Atualmente os protocolos mais utilizados para indução da ovulação utilizam GnRH e estrógenos. Recentemente, foi demonstrado que as prostaglandinas possuem efeitos positivos na indução do processo ovulatório, mas seu mecanismo de ação não está totalmente esclarecido. A presente revisão tem por objetivo abordar os principais indutores da ovulação utilizados em protocolos para controle do ciclo estral em bovinos, relatando o período de ocorrência das ovulações após a sua aplicação.
Several hormones may be used in protocols aimed to optimize reproductive biotechniques such as artificial insemination (AI) and fixed-timed artificial insemination (FTAI) which require precise control of the estrous cycle and the ovulation. Some hormones act on the hypothalamic-pituitary axis, such as the gonadotrophin releasing hormone (GnRH) and estradiol esters such as estradiol benzoate (EB) and cypionate (EC), whereas others act directly on the ovaries, such as human chorionic gonadotrophin (hCG) and luteinizing hormone (LH). Currently, the most commonly used protocols for ovulation induction use GnRH or estrogen. Prostaglandins have recently been shown to have positive effects on induction of the ovulatory process, but their mechanism of action is not fully understood. The present review aims to address the main ovulation inducers used in protocols to control the estrous cycle in cattle, emphasizing the period between their administration and the occurrence of ovulation.
Assuntos
Feminino , Animais , Bovinos , Bovinos/fisiologia , Hormônios Esteroides Gonadais/análise , Indução da Ovulação/métodos , Indução da Ovulação/veterináriaRESUMO
A eficiência reprodutiva na bovinocultura é essencial para a produtividade e lucratividade do sistema. O ambiente uterino tem importância fundamental para o estabelecimento e manutenção da gestação em diferentes espécies e pode ser influenciado pela ação de diversos hormônios. Sabe-se que as concentrações fisiológicas de estrógeno possuem efeito sobre a imunidade, estrutura e funcionalidade uterina. Alguns autores utilizaram administrações de estrógeno, em doses isoladas, como profilaxia ou terapia em casos de infertilidade, entretanto, não foram observados efeitos benéficos ou até mesmo houve um aumento da contaminação bacteriana. Porém, outros estudos que utilizaram repetidas doses de estrógeno demonstraram efeitos positivos no desempenho reprodutivo em vacas repetidoras. Ainda, protocolos de inseminação artificial em tempo fixo (IATF) com suplementação de estrógeno ou com período prolongado de proestro têm possibilitado maiores taxas de prenhez e menos perdas gestacionais. Com base nisso, se faz necessário a realização de pesquisas que abordem o efeito do estrógeno sobre a fertilidade em condições controladas. O objetivo desta revisão é discutir aspectos relacionados a exposição ao estrógeno para prevenção ou terapia de transtornos reprodutivos com foco no ambiente uterino.(AU)
Reproductive efficiency in cattle is essential for the productivity and profitability of the system. The uterine environment has a fundamental importance for pregnancy establishment and maintenance in different species and can be influenced by the action of several hormones. It is well established that physiological concentrations of estrogen have effect on the uterine immunity, structure and functionality. Some authors evaluated estrogen administration, in single doses, for prophylaxis or therapy of infertility; however, no beneficial effects were observed, and, in some cases, there was an increase in bacterial contamination. Conversely, other studies using repeated doses of estrogen demonstrated positive effects on reproductive performance in repeat breeder cows. Furthermore, timedartificial insemination (TAI) protocols using estrogen or with prolonged proestrus are associated with increased pregnancy rates and seem to prevent pregnancy losses. Based on this, it is necessary to perform studies evaluating the effect of estrogen on fertility under controlled conditions. The objective of this review is to discuss aspects related to the exposure to estrogens to prevent or overcome reproductive disorders focusing on the uterine environment.(AU)
Assuntos
Animais , Feminino , Bovinos , Estrogênios/análogos & derivados , Estrogênios/análiseRESUMO
Background: Diarrhea generates economic impacts due high morbidity and mortality losses, and results in delayed physical development and treatment costs. The therapy consists in using broad-spectrum antibiotics, such as drugs belongingto the quinolones group, as the enrofloxacin. It is currently available on the market a single dose enrofloxacin, whichreaches plasma peak concentration five hours after the injection, and in 30 minutes reaches the therapeutic concentrationsin plasma. The aim of this study was to evaluate the clinical, haematological and biochemical parameters in calves withdiarrhea treated with a single dose of a fast action response enrofloxacin.Materials, Methods & Results: For this study, 10 heifers with 1 day of life were classified according appearance of diarrhea clinical symptoms in two experimental groups: Sickness Group (SG) n = 5 and Healthy Group (HG) n = 5. For theSG, the adopted therapeutic protocol was a single dose (7.5 mg / kg / IM) of a fast action enrofloxacin and the GS animalswere not treated. During the first five weeks of life, the animals were clinically monitored (heart rate, respiratory rate, rectaltemperature and capillary refill time) and blood samples were collected for hemogram and biochemical analysis of albumin(ALB), total protein (TP) and globulin (GLO), and determination of the relations ALB:GLO and TP:fibrinogen. Besides,the growth measures were used to obtain the average daily gain (ADG) of weight, height, chest girth and rump width.From the diagnosis of diarrhea, the animals were monitored daily for 3 consecutive days by clinical examination and bloodcollection for hemogram. The statistical analyzes were performed by using version 9.0 SAS software. The ADG of weight,height, chest girth, rump width and concentrations of blood metabolites (ALB, TP, GLO, ALB:GLO, TP:Fibrinogen) didnot differ between the groups during the first five weeks of life. Frequencies of heart rate (HR)...
Assuntos
Animais , Bovinos , Enrofloxacina/administração & dosagem , Enrofloxacina/análise , Fibrinogênio , Rotavirus , Animais Recém-Nascidos , Antibacterianos , Testes Hematológicos/veterináriaRESUMO
Background: Diarrhea generates economic impacts due high morbidity and mortality losses, and results in delayed physical development and treatment costs. The therapy consists in using broad-spectrum antibiotics, such as drugs belongingto the quinolones group, as the enrofloxacin. It is currently available on the market a single dose enrofloxacin, whichreaches plasma peak concentration five hours after the injection, and in 30 minutes reaches the therapeutic concentrationsin plasma. The aim of this study was to evaluate the clinical, haematological and biochemical parameters in calves withdiarrhea treated with a single dose of a fast action response enrofloxacin.Materials, Methods & Results: For this study, 10 heifers with 1 day of life were classified according appearance of diarrhea clinical symptoms in two experimental groups: Sickness Group (SG) n = 5 and Healthy Group (HG) n = 5. For theSG, the adopted therapeutic protocol was a single dose (7.5 mg / kg / IM) of a fast action enrofloxacin and the GS animalswere not treated. During the first five weeks of life, the animals were clinically monitored (heart rate, respiratory rate, rectaltemperature and capillary refill time) and blood samples were collected for hemogram and biochemical analysis of albumin(ALB), total protein (TP) and globulin (GLO), and determination of the relations ALB:GLO and TP:fibrinogen. Besides,the growth measures were used to obtain the average daily gain (ADG) of weight, height, chest girth and rump width.From the diagnosis of diarrhea, the animals were monitored daily for 3 consecutive days by clinical examination and bloodcollection for hemogram. The statistical analyzes were performed by using version 9.0 SAS software. The ADG of weight,height, chest girth, rump width and concentrations of blood metabolites (ALB, TP, GLO, ALB:GLO, TP:Fibrinogen) didnot differ between the groups during the first five weeks of life. Frequencies of heart rate (HR)...(AU)