Breeding techniques of small-tailed Han Sheep

Small-tailed Han sheep has fast growth, precocious maturity, strong fecundity, stable genetic performance and strong adaptability, so it is regarded as a famous animal breed by the state, and is praised as China's "national treasure", the world's "super sheep" and "high-legged sheep".

Estrus season

Small-tailed Han sheep belong to animals that are in estrus many times throughout the year. However, because sheep breed livestock in short days, most of them begin to estrus in the middle of August, when the sunshine changes from long to short and the temperature begins to drop, so the estrus is more in autumn. Therefore, artificial control of light can be used to determine the mating time. Every day in summer, the sheep will be dark for a period of time to shorten the photo studio, so that the breeding season can appear in advance; in autumn, the lighting time in the sheep shed can be extended to make it end before the breeding season.

Temperature has an important effect on ewes' estrus. Every autumn, if the weather clears up after the rain and the weather becomes cool, there will be a batch of estrus sheep in the flock.

Sexual stimulation has a certain effect on ewes' estrus. Putting the ram into the flock can induce the ewe to start estrus or estrus ahead of time.

Nutritional status also has a significant effect on ewes' estrus. If the nutrition is good and the body is good, the estrus starts early. Otherwise, the estrus starts late, the estrus time is short, and the estrous cycle is less.

The ram can be mated all the year round, but the sexual desire is the highest and the semen quality is good in autumn, the lowest in winter and the worst in summer. Shearing rams before hot weather is good for cooling and preventing summer infertility.

Signs of estrus

Ewes are usually excited, restless, shout, climb the wall, reach the door, shake their tails, lose appetite, eat less, the vulva is red and swollen, and the vulva and tail root adhere to secretions. Like to approach the ram and accept the ram's climb. Rams often kiss and smell the pussy of ewes and the urine that ewes spill on the ground. The estrus symptoms of small-tailed Han sheep are not obvious, especially virgin sheep, so we must pay attention to observation, it is best to test estrus with rams, in order to find ewes in time.

When testing with rams, in order to prevent illegal mating, the rams should be dealt with:

1. Tie the test cloth. Use a piece of 40cm × 35cm white cloth and tie it with four corners and hang it under the belly of the sheep.

2. Displacement of penis. So that it can only climb and not mate.

Duration of estrus

The time from the beginning of estrus symptoms to the end of estrus symptoms is the duration of estrus. The estrus duration of small-tailed Han sheep was 1.5-2 days, with an average of 44 hours.

Estrous cycle

Ewes have a series of periodic changes in their sexual organs and the whole organism from the previous estrus to the next estrus. This recurrent sexual activity is called the estrous cycle. According to the changes of maternal ovary, reproductive tract and vulva, an estrous cycle can be divided into four stages: proestrus, estrus, metestrus and estrous phase. The estrous cycle of small-tailed Han sheep was 15-21 days, with an average of 18 days.

Ewes are called postpartum estrus if they can still be in estrus during the breeding season. The time of postpartum estrus is 20-60 days postpartum. The average was 35 days.

Mating season

The mating season should be determined according to the estrus season, planned lambing times and lambing time. If you want to give birth to lambs from January to February, you need to breed from August to September, and if you want to produce lambs from March to April, you need to mate from October to November.

The lambs from August to September every year and the lambs from January to February of the following year are winter lambs. Winter lambs have the advantages of important birth, rapid growth, high survival rate and good uniformity, so winter lambs should be arranged as far as possible in places where conditions permit.

Mating time

Sheep ovulate at 8-24 hours after the onset of estrus, and the fertilisable life span of the ovulated eggs is about 12 hours, and the suitable time for fertilization is 8-20 hours after estrous. Therefore, the suitable time for mating is 8-20 hours after estrus. At this time, the input sperm and the ovum can meet synchronously at one and three places on the fallopian tube. In order to ensure the conception rate, repeated mating is often carried out in practice, that is, ewes detected in the morning are mated once in the morning and once in the afternoon, and ewes detected in the afternoon are mated once in the evening and once again in the next morning. The interval between the two mating is 8 to 16 hours. Generally, one estrus can be matched twice.

Mating method

1. Free mating: that is, male and ewe are usually raised in mixed herds. after ewe is in estrus, rams mate freely. The advantage is to save labor and materials, as long as the male-female ratio is appropriate, the ram is energetic, semen quality, conception rate is also quite high. The disadvantages are that rams chase ewes and affect fattening; lambing periods are different, so it is not convenient to manage; inbreeding is inevitable, resulting in inbreeding decline; it is impossible to know the expected delivery date; and it is easy to spread reproductive tract diseases. The way to overcome the above shortcomings is to raise the rams separately during the non-mating period, and to arrange and exchange rams for each group of ewes in a planned way during the mating period.

2. Artificial assisted mating: it can make ewes mate with rams in a planned way. This method is beneficial to improve the utilization rate of ram, select and match reasonably, and determine the expected delivery date. The method is to raise the rams and ewes separately, and when the ewes are in estrus, choose a suitable ram for mating. By using this method, it is necessary to timely and accurately grasp the ewe's estrus and try the estrus as much as possible to ensure that the timing of mating is not lost.

3. Artificial insemination: it is an advanced breeding technique that uses workers' insemination equipment to take the semen of rams, after quality inspection, vitality determination, dilution and other treatment, and then transferred to the reproductive organs of ewes to make them pregnant. Artificial insemination can improve the utilization rate of superior bred rams. Males can match 10 to 15 ewes in one semen collection and 300 to 500 ewes in one breeding season. In this method, a ram can only match a few ewes a day, and a breeding season can only match about 100 ewes. As the breeding ram and ewe do not have direct contact, the transmission of some diseases can be avoided.