What measures are there to improve the fertility of sheep flocks in agricultural areas?
What measures are there to improve the fertility of sheep flocks in agricultural areas?
(Agricultural Wealth Network) What measures are there to improve the fertility of sheep flocks in agricultural areas?
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1 Select high-quality breeding sheep
There is a great degree of variation in fertility among ewes of different breeds. For example, the twin-lamb rate of China's Hu sheep, Small-tailed Han sheep, and Finland's Landrace sheep is much higher than that of other breeds, with lambing rates reaching 200%-300%. According to another report, the Qingtian goat in the Jining area of Shandong has very strong multiple-birth capacity, sometimes producing 3-5 kids per litter. The fertility of ewes is hereditary; generally, ewes that produce twins will pass this high fertility on to their offspring. Research shows that: ewes with a single lamb at first parity had average lamb counts of 1.33, 1.31, and 1.04 in the following three parities; while ewes with twins at first parity had lamb counts of 1.73, 1.71, and 1.88 in the following three parities, respectively. Therefore, introducing high-yielding breeds for crossbreeding improvement and carrying out selection and breeding of one's existing flock will, over the long term, improve the fertility of the entire flock. High-quality breeding rams can be selected through their mother's reproductive performance and progeny testing, and must come from the offspring of high-yielding ewes.
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2 Improve the feeding level of breeding rams and breeding ewes
Nutritional conditions have a great influence on the reproductive capacity of rams and ewes. Sufficient and complete nutrition can increase the libido of breeding rams, improve semen quality, and at the same time promote estrus and increase ovulation numbers in ewes. The following uses the feeding of Small-tailed Han sheep as an example.
2.1 Feeding of breeding rams
Breeding rams should be kept robust during feeding, with a body condition above medium. The forage fed at ordinary times should be nutritionally complete, and it is recommended to use high-quality forage such as alfalfa. For breeding rams mainly raised by grazing, during the non-mating season, supplement each ram daily with 0.5 kg of concentrate, 2 kg of dry grass, 0.5 kg of green feed, 5-10 g of salt, and 5-10 g of bone meal. Starting 40 days before mating, supplement daily with 0.7-0.8 kg of concentrate, gradually increasing thereafter. During the mating period, supplement daily with about 1.2 kg of concentrate, 2.5 kg of green hay, 0.5-1 kg of carrots, 2-3 eggs, 5-10 g of salt, and 5-10 g of bone meal, with appropriate grazing. Maintain about 2 hours of exercise daily, and massage the testicles every day. For breeding rams raised in housing, during the non-mating season, feed daily 2.5 kg of high-quality hay, 1.0-1.5 kg of succulent feed, and 0.8 kg of mixed concentrate; during the mating period, feed daily 1.0-1.5 kg of green feed, 1.0-2.0 kg of mixed concentrate, 2-3 eggs, 5-10 g of salt, and 5-10 g of bone meal.
2.2 Feeding of breeding ewes
Under grazing conditions, ewes in the non-pregnant period do not need supplementary feeding if they can eat their fill every day; in winter, some dry grass can be appropriately supplemented. For breeding ewes in poor body condition, short-term flushing can be carried out about 40 days before mating to promote estrus and ovulation. Be careful to keep ewes at a body condition score of 7-8. In the first 3 months of gestation, fetal development is slow, and except during the dry-grass period, no supplementary feeding is needed. In the last 2 months of gestation, the fetus grows rapidly, and the ewe's energy metabolism and material metabolism increase by 30%-40% compared with the non-pregnant period. At this time, each ewe can be supplemented daily with 0.45 kg of mixed concentrate, 1-1.5 kg of green hay, 0.5 kg of green feed, and 5-10 g of bone meal. During gestation, attention should be paid to protecting the fetus and minimizing stress on the ewe. In the lactation period, for ewes that gave birth to a single lamb, 0.3-0.5 kg of concentrate, 0.5 kg of green hay, and 1.5 kg of succulent feed should be given daily. For ewes that gave birth to twins, supplement daily with 0.4-0.6 kg of mixed feed, 1 kg of green hay, and 1.5 kg of succulent feed. In the late lactation period, because lambs no longer rely entirely on breast milk as their main nutrient source, the amount fed to ewes should be appropriately reduced.
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3 Maintain an appropriate proportion of breedable ewes in the flock
Whether the flock structure is reasonable has a great influence on the fertility of the flock. The twin-lamb rate of ewes increases with age, reaching the highest level after 1-3 years, and beginning to decline after the 6th-7th parity. The reasons for the decline in fertility of old ewes are mainly the decline of sexual function, poor egg quality, and weakened uterine function, resulting in a lower conception rate and an increase in embryonic death. Therefore, increasing the proportion of ewes of suitable age (2-5 years old) in the flock is an important measure to improve sheep fertility. On breeding sheep farms, the proportion of breedable ewes of suitable age can be increased to 60%-70%; in the vast agricultural areas, it should generally be controlled at above 40%-50%.
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4 Carry out mating scientifically
4.1 Selection of mating season
The timing of mating is mainly determined by what time of lambing is most conducive to lamb survival and the health and strength of both mother and offspring. In summer, the weather is hot, the libido of rams weakens, and semen quality declines; in winter, ewes are in poor body condition and are not easy to come into estrus, or the conception rate during estrus is low. In most areas of our province, the practice adopted is mating only once a year, in autumn, that is, mating in October-November each year and lambing in March-April of the following year. The advantages of this mating arrangement are: when the ewe is pregnant, because nutritional conditions are relatively good, the birth weight of the lamb is relatively large, and after weaning the lamb can eat green grass, so it grows and develops relatively quickly, and its ability to overwinter and pass through spring in the first year is relatively strong. In addition to autumn mating, mating can also be carried out in spring, that is, in April-May each year; mating at this time requires storing enough forage and feed in winter and preparing a sheep house with good insulation.
4.2 Scientific mating methods
There are two mating methods for sheep, namely natural mating and artificial insemination. Natural mating is the most primitive method in sheep raising, that is, grazing rams and ewes of the breeding season together in one flock. It saves labor and requires no equipment. However, applying this method has many adverse effects on the fertility of the entire flock. Due to inbreeding and not knowing the blood relationship of the sheep, it brings difficulties to future selection and mating, and also produces many deformed fetuses, directly reducing the fertility of the flock. Carrying out artificial insemination can effectively improve the above shortcomings. It can expand the utilization rate of excellent rams, improve the conception rate of ewes, and is of great help in improving the fertility of the flock. If artificial insemination is not carried out, artificial assisted mating can be used, that is, grazing rams and ewes separately and testing the ewes for estrus every day during the mating season, then mating the ewes in estrus with designated rams. This is conducive to selection and mating of sheep.
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5 Strengthen management before and after lambing
Before lambing, various instruments should be disinfected, and the ewe's tail root, vulva, anus, and udder should be disinfected with 1% Lysol or 1‰ potassium permanganate solution. After the lamb is born, cut the umbilical cord briefly at a distance of 5-8 cm from the lamb's navel and disinfect it with iodine tincture. If there is a lamb with apparent death, promptly lift its hind limbs, pat its back, or let it lie flat and use both hands to press its chest rhythmically to revive it. When dystocia occurs, after checking the fetal position, manual assistance can be carried out; otherwise, find a veterinarian to perform a cesarean section. After the fetus is born, let it suckle colostrum in time, start feeding early, train it to eat grass, expel meconium, and enhance gastrointestinal motility. Newborn lambs have relatively poor resistance and should be carefully cared for. If the ewe's milk is insufficient, artificial feeding or foster care should be adopted in time.
--------------------------------------
1 Select high-quality breeding sheep
There is a great degree of variation in fertility among ewes of different breeds. For example, the twin-lamb rate of China's Hu sheep, Small-tailed Han sheep, and Finland's Landrace sheep is much higher than that of other breeds, with lambing rates reaching 200%-300%. According to another report, the Qingtian goat in the Jining area of Shandong has very strong multiple-birth capacity, sometimes producing 3-5 kids per litter. The fertility of ewes is hereditary; generally, ewes that produce twins will pass this high fertility on to their offspring. Research shows that: ewes with a single lamb at first parity had average lamb counts of 1.33, 1.31, and 1.04 in the following three parities; while ewes with twins at first parity had lamb counts of 1.73, 1.71, and 1.88 in the following three parities, respectively. Therefore, introducing high-yielding breeds for crossbreeding improvement and carrying out selection and breeding of one's existing flock will, over the long term, improve the fertility of the entire flock. High-quality breeding rams can be selected through their mother's reproductive performance and progeny testing, and must come from the offspring of high-yielding ewes.
--------------------------------------
2 Improve the feeding level of breeding rams and breeding ewes
Nutritional conditions have a great influence on the reproductive capacity of rams and ewes. Sufficient and complete nutrition can increase the libido of breeding rams, improve semen quality, and at the same time promote estrus and increase ovulation numbers in ewes. The following uses the feeding of Small-tailed Han sheep as an example.
2.1 Feeding of breeding rams
Breeding rams should be kept robust during feeding, with a body condition above medium. The forage fed at ordinary times should be nutritionally complete, and it is recommended to use high-quality forage such as alfalfa. For breeding rams mainly raised by grazing, during the non-mating season, supplement each ram daily with 0.5 kg of concentrate, 2 kg of dry grass, 0.5 kg of green feed, 5-10 g of salt, and 5-10 g of bone meal. Starting 40 days before mating, supplement daily with 0.7-0.8 kg of concentrate, gradually increasing thereafter. During the mating period, supplement daily with about 1.2 kg of concentrate, 2.5 kg of green hay, 0.5-1 kg of carrots, 2-3 eggs, 5-10 g of salt, and 5-10 g of bone meal, with appropriate grazing. Maintain about 2 hours of exercise daily, and massage the testicles every day. For breeding rams raised in housing, during the non-mating season, feed daily 2.5 kg of high-quality hay, 1.0-1.5 kg of succulent feed, and 0.8 kg of mixed concentrate; during the mating period, feed daily 1.0-1.5 kg of green feed, 1.0-2.0 kg of mixed concentrate, 2-3 eggs, 5-10 g of salt, and 5-10 g of bone meal.
2.2 Feeding of breeding ewes
Under grazing conditions, ewes in the non-pregnant period do not need supplementary feeding if they can eat their fill every day; in winter, some dry grass can be appropriately supplemented. For breeding ewes in poor body condition, short-term flushing can be carried out about 40 days before mating to promote estrus and ovulation. Be careful to keep ewes at a body condition score of 7-8. In the first 3 months of gestation, fetal development is slow, and except during the dry-grass period, no supplementary feeding is needed. In the last 2 months of gestation, the fetus grows rapidly, and the ewe's energy metabolism and material metabolism increase by 30%-40% compared with the non-pregnant period. At this time, each ewe can be supplemented daily with 0.45 kg of mixed concentrate, 1-1.5 kg of green hay, 0.5 kg of green feed, and 5-10 g of bone meal. During gestation, attention should be paid to protecting the fetus and minimizing stress on the ewe. In the lactation period, for ewes that gave birth to a single lamb, 0.3-0.5 kg of concentrate, 0.5 kg of green hay, and 1.5 kg of succulent feed should be given daily. For ewes that gave birth to twins, supplement daily with 0.4-0.6 kg of mixed feed, 1 kg of green hay, and 1.5 kg of succulent feed. In the late lactation period, because lambs no longer rely entirely on breast milk as their main nutrient source, the amount fed to ewes should be appropriately reduced.
--------------------------------------
3 Maintain an appropriate proportion of breedable ewes in the flock
Whether the flock structure is reasonable has a great influence on the fertility of the flock. The twin-lamb rate of ewes increases with age, reaching the highest level after 1-3 years, and beginning to decline after the 6th-7th parity. The reasons for the decline in fertility of old ewes are mainly the decline of sexual function, poor egg quality, and weakened uterine function, resulting in a lower conception rate and an increase in embryonic death. Therefore, increasing the proportion of ewes of suitable age (2-5 years old) in the flock is an important measure to improve sheep fertility. On breeding sheep farms, the proportion of breedable ewes of suitable age can be increased to 60%-70%; in the vast agricultural areas, it should generally be controlled at above 40%-50%.
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4 Carry out mating scientifically
4.1 Selection of mating season
The timing of mating is mainly determined by what time of lambing is most conducive to lamb survival and the health and strength of both mother and offspring. In summer, the weather is hot, the libido of rams weakens, and semen quality declines; in winter, ewes are in poor body condition and are not easy to come into estrus, or the conception rate during estrus is low. In most areas of our province, the practice adopted is mating only once a year, in autumn, that is, mating in October-November each year and lambing in March-April of the following year. The advantages of this mating arrangement are: when the ewe is pregnant, because nutritional conditions are relatively good, the birth weight of the lamb is relatively large, and after weaning the lamb can eat green grass, so it grows and develops relatively quickly, and its ability to overwinter and pass through spring in the first year is relatively strong. In addition to autumn mating, mating can also be carried out in spring, that is, in April-May each year; mating at this time requires storing enough forage and feed in winter and preparing a sheep house with good insulation.
4.2 Scientific mating methods
There are two mating methods for sheep, namely natural mating and artificial insemination. Natural mating is the most primitive method in sheep raising, that is, grazing rams and ewes of the breeding season together in one flock. It saves labor and requires no equipment. However, applying this method has many adverse effects on the fertility of the entire flock. Due to inbreeding and not knowing the blood relationship of the sheep, it brings difficulties to future selection and mating, and also produces many deformed fetuses, directly reducing the fertility of the flock. Carrying out artificial insemination can effectively improve the above shortcomings. It can expand the utilization rate of excellent rams, improve the conception rate of ewes, and is of great help in improving the fertility of the flock. If artificial insemination is not carried out, artificial assisted mating can be used, that is, grazing rams and ewes separately and testing the ewes for estrus every day during the mating season, then mating the ewes in estrus with designated rams. This is conducive to selection and mating of sheep.
--------------------------------------
5 Strengthen management before and after lambing
Before lambing, various instruments should be disinfected, and the ewe's tail root, vulva, anus, and udder should be disinfected with 1% Lysol or 1‰ potassium permanganate solution. After the lamb is born, cut the umbilical cord briefly at a distance of 5-8 cm from the lamb's navel and disinfect it with iodine tincture. If there is a lamb with apparent death, promptly lift its hind limbs, pat its back, or let it lie flat and use both hands to press its chest rhythmically to revive it. When dystocia occurs, after checking the fetal position, manual assistance can be carried out; otherwise, find a veterinarian to perform a cesarean section. After the fetus is born, let it suckle colostrum in time, start feeding early, train it to eat grass, expel meconium, and enhance gastrointestinal motility. Newborn lambs have relatively poor resistance and should be carefully cared for. If the ewe's milk is insufficient, artificial feeding or foster care should be adopted in time.