Purebred sheep breeding and hybridization techniques

The breeding of sheep includes pure breeding and crossbreeding. Thoroughbred breeding and crossbreeding require pure breeders. With good breeders, good quality offspring can be bred.

It is necessary to strengthen cultivation, create reasonable feeding conditions, ensure normal development, and give full play to heritability in order to select and breed truly excellent breeding sheep.

First, select species

In the breeding process, breeding sheep with good production performance are constantly bred to expand breeding, so as to achieve the purpose of improving economic efficiency. Therefore, selection is the prerequisite and foundation for breeding.

(I) The basis for selection

Selection is based on body appearance, production performance, offspring quality, and ancestry. It is based on individual identification of sheep.

1, body appearance

Body appearance is very important in purebred breeding. Any sheep that does not meet the characteristics of this breed cannot be selected as a target. In addition, body size has a direct relationship with production performance and cannot be ignored. If the body size is neglected, the production performance depends entirely on the actual production performance measurement, which takes time and causes waste. For example, some aspects of meat production performance and reproductive performance can be solved by body type selection.

2, production performance

The production performance refers to the aspects of body weight, slaughter rate, fecundity, lactation force, precocity, wool yield, lamb skin quality.

The production performance of the sheep can be passed on to the offspring through genetics, so selecting the breeding sheep with good production performance is the key link in breeding. However, it is impossible to outperform other varieties in all aspects, and the main advantages should be highlighted.

3, descendants

Whether or not the sheep itself has good performance is a prerequisite for seed selection, but this is only one aspect, and more importantly, whether its excellent performance is passed on to future generations. If good performance cannot be passed on to future generations, it cannot be used as a seed. At the same time, in the selection process, we must continue to select those with good performance as a reserve species.

4, pedigree

The pedigree is the pedigree, which is an important basis for the selection of breeding sheep. It not only provides information on the production performance of the breeding parent, but also records the ancestry of the sheep and is very helpful for the correct selection of breeding sheep.

(B) Method of selecting seeds

1, identification

Selection is based on the identification of sheep. There are two types of sheep identification: individual identification and grade identification. All of them are accurately graded according to the identification item and grade standard. Individual identification requires itemized entry by item, and level identification does not make specific individual records. Only the level number is written. The sheep for individual identification included special grades, first-grade rams and other rams at various levels, adult rams and male lambs to be sold, special ewes, and ewes designated as descendants for testing and their lambs. In addition to the individual identification, all were graded. The grade criteria can be set according to the requirements of breeding objectives.

The identification of sheep is generally performed when the physical appearance and performance of the animal are fully demonstrated and it is possible to make correct judgments. The ram usually reaches adulthood and the ewes are measured for performance after the first lambing. In order to cultivate good lambs, we must identify the first-born and weaned babies at the age of 6 months and at the age of 1 year. The suede-type lambs are identified when the quality of the lambskin and suede are the best. The quality of offspring should also be identified, mainly through the determination of various production performance. The identification of offspring quality is an important basis for selection. All those who do not meet the requirements of the timely phase out, combined with the standard as a kind of use. In addition to quizzes on identifications and descendants, considerations such as adaptability and disease resistance of breeding sheep and descendants should also be examined.

2, review the blood lineage

By examining pedigrees, one can draw conclusions about the kinship between the chosen breeder and his ancestors. The pedigree review requires a detailed record, and all self-bred breeders should make detailed records. When purchasing sheep, they must ask the sales organization and individuals for card information. In the absence of records, they can only use the sheep's individual identification as the basis for selection, and cannot be vetted.

3, choose to stay behind sheep

In order for the selection work to proceed smoothly, it is necessary to choose to reserve the reserve sheep. The selection of reserve breeding sheep should be conducted from the following aspects. The first is to choose nests (see ancestors). From the excellent male and female mating offspring, the whole litter is selected among the well-developed lambs. Ewes need more than second-born lambs. The second is the selection of individuals, to choose to stay in the birth weight and growth at each stage of fast growth, body size, heat early lamb choice. The third is the selection of future generations. It depends on the production performance of the offspring produced by the breeding sheep. Is it passed on to the offspring the excellent performance of the parental generation? No one can inherit the inheritance of this aspect.

The number of reserve ewes is generally 3-5 times the number needed, and the number of reserve rams is also greater than the number needed to prevent the unqualified sheep from being used for breeding in the breeding process.

(III) Selection criteria

According to the breeding goal, the seedlings should be selected according to the standard on body appearance, production performance, body weight, meat production, lambing rate, milk yield, precocity, hair production performance, and performance.

Second, matching

The seed selection is the choice of the sheep's quality. The selection of the breeding sheep also consolidates the effect of seed selection through matching. Therefore, selection is the continuation of seed selection and is an important aspect of the organic connection in breeding work.

(A) The principle of matching

1. Matching should be closely combined with seed selection. The selection needs to consider the need for selection and provide necessary information for it; the selection should be matched with the seed selection so that the beneficial traits of both parents are fixed and passed on to future generations.

2. Use the best ram to choose the best ewes, but the quality and performance of the ram must be higher than that of the ewes. The poor ewes should also mate with the better rams as much as possible. In order to improve the offspring to a certain degree, generally, the second and third-grade rams cannot be used for breeding, and male and female ewes with the same disadvantages are not allowed to be selected.

3, to expand the use of a good ram, it is best to test after descendants, before the hereditary unconfirmed, matching can be based on the sheep's physical appearance and production performance.

4. The merits and demerits of breeding sheep should be judged according to the quality of offspring, so detailed and systematic records are required.

(b) Matching methods

1, quality matching

Homogeneous selection and mating of male and female sheep with the same production characteristics or advantages is aimed at consolidating and improving the common advantages. Homogeneous selection enables future generations to maintain and develop their original characteristics, and the use of hereditary tends to be stable. However, overemphasizing the advantages of homogenous matching can easily lead to unilateral overdevelopment, weakening the constitution and reducing the viability. Therefore, the homogenous matching in the breeding process can be determined according to the actual needs of the breeding work.

Heterogeneous selection, selection of male and female sheep with different advantages for mating, or breeding of good rams and ewes with certain disadvantages, the purpose of which is to use the rights of future generations to combine the advantages of parents, or to overcome the ewes Some disadvantages. The advantages and disadvantages of this matching method are to some extent the opposite of the homogenous matching.

2, the specific application of quality selection

Individual selection is based on the individual identification of the sheep. It is mainly based on the individual identification, production performance, blood energy and offspring quality and other conditions to determine mating both sides. For those ewes that fully meet the breeding direction and achieve the desired performance. You can choose two types of rams. One is homogenous matching, which makes its descendants have better and more stable quality; the second is to carry out heterogenous matching in order to obtain offspring with different quality of parents.

The grade selection is to select rams according to the comprehensive characteristics of each level of ewes, in order to obtain common advantages and common defects.

Kinship matching is the matching of sheep with a certain blood relationship. The role of distant relatives is genetic stability, which is an advantage, but kin selection can easily lead to lower viability of offspring, lambs are weak, physical size is smaller, and production performance is reduced. For kinship mating, the following measures should be taken to prevent the occurrence of adverse consequences. First, strict selection and elimination. It must be matched according to the physique and appearance, so that strong and strong male and female ram breeding can reduce adverse consequences. The offspring generated by the kin selection will be carefully identified, and those who are physically strong and robust will be selected to continue to grow sheep. Individuals with weak physique and low viability should be eliminated. The second is blood renewal, which is to select the offspring that are sibling-matched and have no kinship, and to breed the same variety under different conditions. This will enable them to obtain offspring with strong viability and good production performance.

Third, purebred breeding

(A) Breeding

Strain is a genetically stable group composed of individuals with common characteristics in the breed and related to each other.

1, establish a basic group

To establish a basic group, one is based on kinship groups and the other is trait groups. According to ancestry groups, the pedigrees were firstly analyzed for pedigrees, and the characteristics of the descendants of the ram were ascertained. Descendants of elite rams were selected to establish basic groups, but their descendants did not possess the characteristics of the traits and should not remain in the basic group. This group approach is used in low heritability. According to trait grouping, the basic group is established based on the performance of the traits. This method is based on individual performance groups regardless of blood. The trait group was adopted when the heritability of the herd was high.

2, establish a strain

After the basic group is established, the basic group is generally closed, only the male and female are selected for breeding in the basic group, and the unqualified individuals are eliminated from generation to generation. Each generation is selected according to the characteristics of the breed. The best rams try their best to increase the utilization rate, and the poor quality is unworthy or poorly matched. The kinship mating is indispensable in the formation of the line, generally only for a few generations of inbreds, and later turned to outbreeding, until the outstanding characteristics and genetic stability of the purebred strain has been bred.

(B) Blood Update

Blood renewal is the introduction of another herd of sheep that directs the same lineage with identical genetic and productive performance, but not the same source. Since the male and female of the sauce belongs to the same strain, it is still pure breeding.

Blood update is performed under the following conditions.

One is when there is a negative consequence of inbreeding in a flock or sheep farm due to the small number of sheep.

The second is that when new varieties are introduced into the environment, production performance will be reduced.

Third, when the quality of the sheep reaches a certain level, production performance, adaptability, etc., appear stagnant. In blood renewal, the introduced sheep have no shortcomings in terms of constitution, productivity, and adaptability.

IV. Hybrid Improvement

Hybridization methods mainly include introduction and hybrid hybridization, and economic hybridization.

1, the introduction of hybridization

When some disadvantages cannot be improved in breeding within this species, introduction of hybridization can be used. The introduction of hybridization should be carried out in the same direction of production. The improved species is crossed with the original ewes once and then backcrossed 1-2 times to obtain offspring containing 1/4-1/8 of external blood for self-breeding. Introduction and hybridization are widely used in the sheep industry, and their success or failure depends to a large extent on the selection of breeding rams and the selection of breeding and the breeding conditions of lambs. When introducing a cross, it is important to select the individual species. Therefore, we must select rams that have passed the test of the descendants and have good physical appearance and strong breeding ability. We must also create certain breeding and management conditions for the hybrid sheep and carry out careful matching. In addition, we must strengthen the selection and breeding of the original varieties in order to ensure a good supply of backcrossed sheep.

1. Progressive hybridization

Progressive hybridization is also referred to as absorption hybridization to improve hybridization. After the improved ram hybrids with the local ewes, the first-generation hybrids will be established. After each generation, the ewes produced will continue to be bred with the original improved ram, and the production performance of the 3-5 hybrids will be basically the same. The improved varieties are similar. Hybridization should stop when the hybrid offspring basically reaches the target. Crossbred male and female ewes that meet the requirements can cross.

3, economic hybrid

Economic hybrids use two generations of hybrids to provide products rather than seed. Generation hybrids have heterosis, so they have strong viability, fast growth, and economic applications in fat lamb production. The advantage of economic hybrids is that the first-generation hybrid male lambs grow fast, and the production of commercial meat is of great significance. Its first-generation hybrid ewes can be used not only as mutton sheep but also as a seed to increase production performance.

V. Breeding plans and records

Breeding must be planned. Breeding plans must be developed in conjunction with the environment and feeding management conditions and market needs. To develop breeding objectives, introduction, breeding, and determination of production performance. At the same time, it is well documented during the breeding process that it provides a reliable basis for breeding.

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