1- Department of Animal Science Research, Agricultural and Natural Resources Research and Education Center of Khorasan Razavi Province, Agricultural Research, Education and Extension Organization (AREEO), Mashhad, Iran
2- Department of Animal Science, Faculty of Agriculture, Birjand University, Birjand, Iran
2- Department of Animal Science, Faculty of Agriculture, Birjand University, Birjand, Iran
Abstract: (358 Views)
Extended Abstract
Background: Goat husbandry, as one of the earliest forms of livestock farming, plays a crucial role in fulfilling human nutritional demands. With the growing global population and the consequent rise in demand for animal-derived products, enhancing reproductive efficiency in goats has become increasingly important. In modern goat production systems, breeding programs are central to maximizing economic returns. Reproductive performance is widely recognized as a primary determinant of profitability in livestock enterprises. Therefore, improvements in reproductive traits can substantially enhance the productivity and profitability of goat herds. Strategies to improve reproductive efficiency may include increasing prolificacy (multiple births per kidding), the number of viable offspring per kidding, or the total number of kiddings throughout a doe’s productive lifespan. Such improvements can be achieved through both genetic selection and environmental management practices, including optimized nutrition, housing, and health care. Estrus synchronization has been globally recognized as an effective technique for reproductive management in small ruminants. This method not only improves kidding rates but also facilitates the production of uniform-age kids and enables year-round breeding independent of seasonality. The present study was designed to evaluate the effects of two estrus synchronization protocols—Controlled Internal Drug Release (CIDR) and prostaglandin—on the reproductive performance of native and non-native goat breeds.
Methods: This study was conducted using a completely randomized design involving 90 clinically healthy does, which were randomly assigned to six groups of 15 animals each. The experimental design was based on a combination of three goat breeds (Saanen, Murcia, and Mahabadi) and two synchronization protocols (CIDR and prostaglandin). The CIDR protocol involved the insertion of intravaginal devices containing 300 mg of progesterone for 10 days. In the prostaglandin protocol, two intramuscular injections were administered seven days apart. At the time of CIDR removal or following the second prostaglandin injection, all does received 400 IU of Pregnant Mare Serum Gonadotropin (PMSG) intramuscularly. Estrus detection was carried out between 24 and 54 h post-treatment, and females showing estrus behavior were introduced to fertile bucks for natural mating. Standing estrus and the acceptance of mounting were used as criteria for estrus. Pregnancy was diagnosed 34 days after buck introduction using ultrasonography (8 MHz bovine probe). Reproductive performance parameters, including estrus onset, pregnancy rate, kidding rate, twinning rate, and stillbirth rate, were recorded afterward. Additionally, kid weights at birth, weaning, and three months of age were measured to assess growth performance.
Results: Both synchronization methods effectively induced estrus, but significant breed-specific differences were observed. Data analysis revealed that treatments significantly affected average daily weight gain (P < 0.05), with the highest gain in Mahabadi goats under CIDR and prostaglandin protocols. Estrus rates were 100% across all groups, but CIDR yielded a significantly shorter estrus onset than prostaglandin (P < 0.05). Ovarian indices, such as Graafian follicle counts during estrus, varied among the groups. Saanen goats under CIDR had the highest mean Graafian follicle count, while Murcia goats under prostaglandin showed the lowest. This pattern persisted in other reproductive metrics, including follicle counts at device removal/injection and corpus luteum counts 10 days post-pregnancy. Ovulation rates in non-native breeds were 100% for both methods, whereas Mahabadi goats showed 93% (CIDR) and 96% (prostaglandin) rates. Saanen goats achieved the highest pregnancy rates with both methods, while Mahabadi performed better with CIDR. Notably, prostaglandin reduced stillbirths to 0% in Saanen and Murcia breeds. For kid traits, Mahabadi kids had significantly higher birth weights
(P < 0.05), and weaning/three-month weights were superior in the Mahabadi and Saanen breeds compared to the Murcia.
Conclusion: The results demonstrate that both CIDR and prostaglandin protocols are effective for estrus synchronization in goats, though their efficiency varies across breeds. The CIDR protocol was particularly advantageous for Saanen and Mahabadi goats, reducing estrus onset time and improving pregnancy rates. In contrast, prostaglandin was more beneficial for Murcia goats, primarily due to its ability to eliminate stillbirths. Saanen goats exhibited superior reproductive performance under both treatments, whereas Mahabadi goats, despite producing kids with higher birth weights, showed only moderate reproductive efficiency. These findings underscore the importance of considering breed-specific responses when selecting estrus synchronization strategies and highlight the need to align reproductive management protocols with targeted breeding.
Background: Goat husbandry, as one of the earliest forms of livestock farming, plays a crucial role in fulfilling human nutritional demands. With the growing global population and the consequent rise in demand for animal-derived products, enhancing reproductive efficiency in goats has become increasingly important. In modern goat production systems, breeding programs are central to maximizing economic returns. Reproductive performance is widely recognized as a primary determinant of profitability in livestock enterprises. Therefore, improvements in reproductive traits can substantially enhance the productivity and profitability of goat herds. Strategies to improve reproductive efficiency may include increasing prolificacy (multiple births per kidding), the number of viable offspring per kidding, or the total number of kiddings throughout a doe’s productive lifespan. Such improvements can be achieved through both genetic selection and environmental management practices, including optimized nutrition, housing, and health care. Estrus synchronization has been globally recognized as an effective technique for reproductive management in small ruminants. This method not only improves kidding rates but also facilitates the production of uniform-age kids and enables year-round breeding independent of seasonality. The present study was designed to evaluate the effects of two estrus synchronization protocols—Controlled Internal Drug Release (CIDR) and prostaglandin—on the reproductive performance of native and non-native goat breeds.
Methods: This study was conducted using a completely randomized design involving 90 clinically healthy does, which were randomly assigned to six groups of 15 animals each. The experimental design was based on a combination of three goat breeds (Saanen, Murcia, and Mahabadi) and two synchronization protocols (CIDR and prostaglandin). The CIDR protocol involved the insertion of intravaginal devices containing 300 mg of progesterone for 10 days. In the prostaglandin protocol, two intramuscular injections were administered seven days apart. At the time of CIDR removal or following the second prostaglandin injection, all does received 400 IU of Pregnant Mare Serum Gonadotropin (PMSG) intramuscularly. Estrus detection was carried out between 24 and 54 h post-treatment, and females showing estrus behavior were introduced to fertile bucks for natural mating. Standing estrus and the acceptance of mounting were used as criteria for estrus. Pregnancy was diagnosed 34 days after buck introduction using ultrasonography (8 MHz bovine probe). Reproductive performance parameters, including estrus onset, pregnancy rate, kidding rate, twinning rate, and stillbirth rate, were recorded afterward. Additionally, kid weights at birth, weaning, and three months of age were measured to assess growth performance.
Results: Both synchronization methods effectively induced estrus, but significant breed-specific differences were observed. Data analysis revealed that treatments significantly affected average daily weight gain (P < 0.05), with the highest gain in Mahabadi goats under CIDR and prostaglandin protocols. Estrus rates were 100% across all groups, but CIDR yielded a significantly shorter estrus onset than prostaglandin (P < 0.05). Ovarian indices, such as Graafian follicle counts during estrus, varied among the groups. Saanen goats under CIDR had the highest mean Graafian follicle count, while Murcia goats under prostaglandin showed the lowest. This pattern persisted in other reproductive metrics, including follicle counts at device removal/injection and corpus luteum counts 10 days post-pregnancy. Ovulation rates in non-native breeds were 100% for both methods, whereas Mahabadi goats showed 93% (CIDR) and 96% (prostaglandin) rates. Saanen goats achieved the highest pregnancy rates with both methods, while Mahabadi performed better with CIDR. Notably, prostaglandin reduced stillbirths to 0% in Saanen and Murcia breeds. For kid traits, Mahabadi kids had significantly higher birth weights
(P < 0.05), and weaning/three-month weights were superior in the Mahabadi and Saanen breeds compared to the Murcia.
Conclusion: The results demonstrate that both CIDR and prostaglandin protocols are effective for estrus synchronization in goats, though their efficiency varies across breeds. The CIDR protocol was particularly advantageous for Saanen and Mahabadi goats, reducing estrus onset time and improving pregnancy rates. In contrast, prostaglandin was more beneficial for Murcia goats, primarily due to its ability to eliminate stillbirths. Saanen goats exhibited superior reproductive performance under both treatments, whereas Mahabadi goats, despite producing kids with higher birth weights, showed only moderate reproductive efficiency. These findings underscore the importance of considering breed-specific responses when selecting estrus synchronization strategies and highlight the need to align reproductive management protocols with targeted breeding.
Keywords: Breed-specific response, Birth weight, Pregnancy rate, Reproductive indices, Survival rate
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