RESUMO
Background: Complete isolation of genders allows intense estrous induction and synchronization once rams are introduced in ewe flocks at the onset of the breeding season (BS). This management practice, defined as the male effect, results from a neuroendocrine process mediated by pheromones. The male effect is a straightforward procedure to induce estrous in noncycling ewes, but conditions for its use have not been fully explored. Thus, this study aimed to evaluate hormone levels and ovarian activity of postpartum ewes in anestrus which are subjected to the male effect under different male to female ratios. Material, Methods & Results: Pospartum females were selected according to body condition score and cyclicity status. Females were kept apart from males during 30 days at a distance of 10 m. Anestrus and ovulation were determined by P4 measures on days 10, 20 and 30 after isolation from males. After P4 concentration diagnosis, anestrus ewe (n = 99) were subjected to male to ewe ratios (MFR) of 1:20 (MFR20), 1:30 (MFR30) and 1:40 (MFR40). Santa Inês rams (n = 3) of proven fertility were used. Three females of each group were randomly subjected to blood collection for LH concentration analysis. Ovarian activity was performed by ultrasonography after estrus manifestation in six ewe of each group. Estrus events were observed twice a day during the BS of 35 days, and estrus [...](AU)
Assuntos
Animais , Masculino , Feminino , Fenômenos Reprodutivos Fisiológicos , Ovinos/fisiologia , Anestro , Sincronização do Estro/métodos , Período Pós-Parto , Hormônio Luteinizante , ProgesteronaRESUMO
Background: Complete isolation of genders allows intense estrous induction and synchronization once rams are introduced in ewe flocks at the onset of the breeding season (BS). This management practice, defined as the male effect, results from a neuroendocrine process mediated by pheromones. The male effect is a straightforward procedure to induce estrous in noncycling ewes, but conditions for its use have not been fully explored. Thus, this study aimed to evaluate hormone levels and ovarian activity of postpartum ewes in anestrus which are subjected to the male effect under different male to female ratios. Material, Methods & Results: Pospartum females were selected according to body condition score and cyclicity status. Females were kept apart from males during 30 days at a distance of 10 m. Anestrus and ovulation were determined by P4 measures on days 10, 20 and 30 after isolation from males. After P4 concentration diagnosis, anestrus ewe (n = 99) were subjected to male to ewe ratios (MFR) of 1:20 (MFR20), 1:30 (MFR30) and 1:40 (MFR40). Santa Inês rams (n = 3) of proven fertility were used. Three females of each group were randomly subjected to blood collection for LH concentration analysis. Ovarian activity was performed by ultrasonography after estrus manifestation in six ewe of each group. Estrus events were observed twice a day during the BS of 35 days, and estrus [...]
Assuntos
Masculino , Feminino , Animais , Anestro , Fenômenos Reprodutivos Fisiológicos , Ovinos/fisiologia , Sincronização do Estro/métodos , Hormônio Luteinizante , Período Pós-Parto , ProgesteronaRESUMO
This study was aimed to evaluate breeding seasons of different durations under contrasting climatic conditions upon reproductive performance of nulliparous does submitted to male effect. A total of 240 Anglo-Nubian females at 8 to 12 months of age were used and were kept away from all three bucks at a distance of 300 m for 60 days, which avoided any physical, visual, olfactory or hearing contact between genders. Estrus were visually detected and pregnancy rates were determined by ultrasonography 60 days after the last mating. Breeding season duration and climatic condition did not influence estrus incidence, where 70% does had estrus detected at the dry season, 80% of does cycled at the rainy season within breeding seasons of 25 days. Moreover, 80% of does cycled at the dry season and 95% at the rainy season during breeding seasons of 35 days and 45 days. After breeding seasons of 25 days, pregnancy rate was lower at the dry season (55.0%) compared to the rainy season (80.0%). Mean birth weight of resulting offspring was lower during the rainy season (2.94 kg ± 0.26) than during the dry season (3.03 kg ± 0.16). The results show that estrus onset is affected by breeding season durations and climatic conditions tested, although dry season lowered pregnancy rates. In conclusion, 25-day breeding seasons are recommended to improve standardization of offspring lots, to reduce costs with food supplementation and estrus detection, while preserving pregnancy and kidding rates.
Assuntos
Animais , Cabras , Estro , Reprodução , Ruminantes , Sincronização do Estro , Detecção do Estro , Estação Chuvosa , Estação SecaRESUMO
This study was aimed to evaluate breeding seasons of different durations under contrasting climatic conditions upon reproductive performance of nulliparous does submitted to male effect. A total of 240 Anglo-Nubian females at 8 to 12 months of age were used and were kept away from all three bucks at a distance of 300 m for 60 days, which avoided any physical, visual, olfactory or hearing contact between genders. Estrus were visually detected and pregnancy rates were determined by ultrasonography 60 days after the last mating. Breeding season duration and climatic condition did not influence estrus incidence, where 70% does had estrus detected at the dry season, 80% of does cycled at the rainy season within breeding seasons of 25 days. Moreover, 80% of does cycled at the dry season and 95% at the rainy season during breeding seasons of 35 days and 45 days. After breeding seasons of 25 days, pregnancy rate was lower at the dry season (55.0%) compared to the rainy season (80.0%). Mean birth weight of resulting offspring was lower during the rainy season (2.94 kg ± 0.26) than during the dry season (3.03 kg ± 0.16). The results show that estrus onset is affected by breeding season durations and climatic conditions tested, although dry season lowered pregnancy rates. In conclusion, 25-day breeding seasons are recommended to improve standardization of offspring lots, to reduce costs with food supplementation and estrus detection, while preserving pregnancy and kidding rates.(AU)
Assuntos
Animais , Cabras , Ruminantes , Reprodução , Estro , Sincronização do Estro , Detecção do Estro , Estação Seca , Estação ChuvosaRESUMO
The objective of this study was to identify the migration period of the genital tubercle and the period of visualization of external genital structures in fetuses of the Dorper breed of sheep derived from natural mating and from fresh, frozen and vitrified embryo transfer. Transrectal ultrasound was performed using a double-frequency linear transducer (6.0 and 8.0 MHz) to monitor 130 ewe fetuses distributed in the four treatments regarding embryo origin. The accuracy of the ultrasound was 100% in this experiment. The fetuses originated from controlled natural mating (NM) and from fresh (FrE), frozen (FE) and vitrified (VE) embryo transfer, with embryos collected 7 days after breeding. Migration of the genital tubercle occurred earlier (P<0.05) in NM (42.21+/-2.86 days) than in FrE (43.98+/-3.00 days), FE (44.97+/-1.83 days) and VE (44.58+/-1.97 days). Visualization of the scrotal bag, prepuce and vulva occurred, respectively, earlier (P<0.05) in NM (45.22+/-1.25, 45.95+/-1.53 and 45.01+/-1.03 days) than in FrE (48.91+/-1.92, 48.52+/-1.41 and 47.41+/-1.41 days), FE (49.97+/-1.08, 49.18+/-2.00 and 47.64+/-1.82 days) and VE (50.12+/-1.66, 49.27+/-1.61 and 47.93+/-1.92 days). The results show that fetal sexing can be accomplished from the 50th day onward in fetuses produced by natural mating and from the 55th day onward in fetuses derived from fresh, frozen and vitrified embryos. It can also be concluded that real-time ultrasonography is a reliable tool for fetal sex determination in sheep taking into account both the location of the genital tubercle and the identification of external genital structures.
Assuntos
Clonagem de Organismos/métodos , Transferência Embrionária/métodos , Transferência Embrionária/veterinária , Análise para Determinação do Sexo/métodos , Carneiro Doméstico/embriologia , Ultrassonografia Pré-Natal/métodos , Ultrassonografia Pré-Natal/veterinária , Animais , Feminino , Gravidez , Prenhez , Reprodutibilidade dos Testes , Técnicas de Reprodução Assistida , Ovinos , Ultrassonografia/métodosRESUMO
This study aimed to assess the opacification period and diagnostic quality of ioversol 240 mg I/ml in the thoracic and lumbar regions after intracisternally injected, and evaluate its effects on the nervous system by clinical and neurological examinations. Thirty clinically normal non-descript dogs without sex distinction, weighing 9-12 kg were divided into three groups of 10 animals each. All the animals were anaesthetized using diazepam and thiopental sodium. Ioversol was injected at a dose of 0.5ml/kg. Cervical radiographs after 5 minutes to confirm injection of the contrast, and thoracolumbar radiographs after 30, 40, 50 and 60 minutes to evaluate the opacification period were taken. Clinical and neurological examinations were performed daily until 7, 14 and 28 days for groups I, II and III respectively. Adverse reactions such as pedal movements, preconvulsive behavior, muscular spasms, apnea, dyspnea, and vomit anxiety were observed during the myelographic procedure only. Ioversol showed good radiopacity, diffusion and miscibility with the cerebrospinal fluid. Reduction of costs also was possible since it can be autoclaved. Opacification period with diagnostic value was of 60 minutes in 60 percent of thoracic radiographs and in 80 percent of lumbar radiographs. Ioversol showed low incidence of clinical and neurological alterations. It is concluded that ioversol 240 mg I/ml is appropriate and safe to be used for myelography in dogs