One is breeding of elite sheep and the other is hybridization. These two concepts are independent and indivisible. The first is the breeding of elite mutton sheep. During the breeding of elite breeders, attention should be paid to the following issues:
First, it is necessary to establish the goal and direction of breeding.
Second, establish a standardized breeder ram breeding and management system, make reasonable use of rams, avoid inbreeding, and focus on seed selection.
Third, to strengthen the feeding and management of basic ewes, especially to strengthen the management of the late pregnancy and the maternity period, so that the pre-production ewes can be raised individually to prevent miscarriage.
Fourth, increase the capital investment and policy support for the improvement of regional breeding of elite sheep and sheep. Introduce encouraging policies and increase subsidies. All kinds of ram cultivation and introduction, breeding of reserve breeding stocks, etc., provide funding and project inclinations, and speed up the process of improving local breeder mutton breeding.
Fifth, increase the cultivation of reserve rams. Sixth, establish a breeding system for improved varieties and do a good job in the industrial development of improved varieties.
Followed by hybridization and utilization. We should first understand what crossbreeding is. Hybridization is not just the use of hybrids for production. The genetic value of a hybrid is composed of two parts. One is the “additive effect valueâ€, which is determined by the average breeding value of the parents; the second is the heterosis, which is determined by the interaction effect of the parents' genes. Only high heterosis, the genetic value of hybrids is not necessarily high. Therefore, hybridization is not a simple hybridization, but first the parental population should be purified and the breeding value should be raised. Then the hybrid combination with the highest heterosis and the best complementing effect should be selected through the combining ability test. The establishment of a supporting line is the best way to use hybrids. The two basic steps in supporting line breeding are the cultivation of specialized strains and the determination of combining ability.
Specialized strains refer to strains whose production performance is “specializedâ€. They are differentiated and bred according to breeding objectives. Each strain has outstanding advantages in certain aspects. Different strains are assigned to designated positions in different levels within the complete breeding system. Special task. The method for establishing specialized strains is generally open core group breeding. Here, the breeding steps for specialized strains are briefly introduced.
First, make clear the breeding goal. Before the establishment of specialized strains, it is necessary to determine the use of several lines to produce hybrid products and livestock, and to determine the parent and maternity.
Second, set up a basic group. The following questions should be considered when forming a basic group: First, the source of the basic group, that is, whether the specialized strain is based on pure breeding or on hybrid basis. In contrast, based on the heterogeneity of the hybrids, the establishment of the ideal hybrid parent can be faster, but the basic group size of this method is larger. Second, pay attention to the quality of the basic group. The basic group must have a wide genetic base, individuals in the basic group must have outstanding advantages, and the individual's inbreeding coefficient in the basic group should be as small as possible. Third, the number of basic groups must not be too small or too large.
Again, clearly choose the options and options. When constructing a department, the early stage should focus on genetic recombination, and in the later stage, gene homozygosis should be included; as for selection, the process should always be carried out. When selecting, it should be based on performance measurement results to improve the accuracy of the selection.
Fourth, the most important feature of the breeding of open core groups is that if new individuals are found after the establishment of the line, or that outstanding offspring are found in the breeding colony, they can be enriched in the core population to add new ideal genes and gene combinations. In the process of building a system, attention should also be paid to moderate inbreeding. Generally, the average in-breeding coefficient of 5 to 6 generations is 10% to 15%.
In the process of cultivating specialized strains, it is generally required that from the third generation onwards, each generation should carry out the determination of combining ability to test the general combining ability of the specialized strains and the position of the specialized strains in the matching hybridization, and at the same time find the most The best combination of crossbreeding is to promote the application in production. This is also the difference between the breeding of specialized strains and the breeding of traditional strains.
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