ABSTRACT
Background: The male effect is an attractive strategy to increase herd production by concentrating mating events and deliveries and further allowing the adoption of genetic improvement programs. It holds similar efficiency to those chemically based estrous synchronization methods, but has the advantage of being a natural method. The work was aimed to evaluate the influence of male effect on estrous induction and synchronization, pregnancy and prolificacy of nulliparous Santa Inês and Morada Nova ewes raised in Semiarid and Zona da Mata regions of Pernambuco state. Materials, Methods & Results: Santa Inês (n = 80) and Morada Nova (n = 80) females, with age from 11 to 12 months, after being evaluated and selected, were identified with plastic ear tags, weighted and maintained isolated from males, during 30 days before experiment onset, without any physical, visual, olfactive and auditive contact. Estrous events were observed twice a day (6:00 and 16:00 h) by trained personnel, during a breeding season of 60 days, and estrous were considered synchronized when detected, within first five days of breeding season. Rams of Santa Inês (n = 2) and Morada Nova (n = 2) breeds were selected based upon reproductive capacity by an andrology exam, and were marked on the externum bone region with a wax and ink (4:1) mixture, and were marked in female lots in order to identify females in [...]
Subject(s)
Animals , Sexual Behavior, Animal/physiology , Estrus/physiology , Fertility/physiology , Sheep/physiology , Estradiol/analysis , Reproductive Physiological Phenomena , Genetic EnhancementABSTRACT
Background: The male effect is an attractive strategy to increase herd production by concentrating mating events and deliveries and further allowing the adoption of genetic improvement programs. It holds similar efficiency to those chemically based estrous synchronization methods, but has the advantage of being a natural method. The work was aimed to evaluate the influence of male effect on estrous induction and synchronization, pregnancy and prolificacy of nulliparous Santa Inês and Morada Nova ewes raised in Semiarid and Zona da Mata regions of Pernambuco state. Materials, Methods & Results: Santa Inês (n = 80) and Morada Nova (n = 80) females, with age from 11 to 12 months, after being evaluated and selected, were identified with plastic ear tags, weighted and maintained isolated from males, during 30 days before experiment onset, without any physical, visual, olfactive and auditive contact. Estrous events were observed twice a day (6:00 and 16:00 h) by trained personnel, during a breeding season of 60 days, and estrous were considered synchronized when detected, within first five days of breeding season. Rams of Santa Inês (n = 2) and Morada Nova (n = 2) breeds were selected based upon reproductive capacity by an andrology exam, and were marked on the externum bone region with a wax and ink (4:1) mixture, and were marked in female lots in order to identify females in [...](AU)
Subject(s)
Animals , Sheep/physiology , Sexual Behavior, Animal/physiology , Estrus/physiology , Fertility/physiology , Reproductive Physiological Phenomena , Genetic Enhancement , Estradiol/analysisABSTRACT
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)
Subject(s)
Animals , Goats , Ruminants , Reproduction , Estrus , Estrus Synchronization , Estrus Detection , Dry Season , Rainy SeasonABSTRACT
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.