"Breeded species" is an abbreviation for fine varieties. It includes new breeds cultivated in China and improved varieties imported from abroad. Judging from the current situation in China, most of the fine rabbit breeds are introduced from abroad. However, the so-called "exotic breeds" cannot be perfect. Due to years of breeding, some have shown degeneration. For example, the US Department of Rex rabbits has been introduced for more than 20 years and it is no longer acceptable to raise it now without breeding. The measures for improved breeding are as follows: (1) Rectifying the rabbit population With the rise of the rex rabbit industry in China, a number of breeder rabbit farms have been established throughout the country. How to carry out breeding of this breed in a new rabbit farm? We believe that we should begin with the reorganization of rabbits. 1 Establish identification standards. Since a newly-built rabbit farm is only transferred to rabbits from other places, it will inevitably lack the necessary records. Therefore, at the beginning, rabbits can only be first evaluated according to the pedigree, growth and development, and appearance, and those individuals that are really poor are eliminated. . When rabbits are reared for a period of time and have obtained certain production records and breeding records, the identification criteria for breeding rabbits should be established according to records, and the rabbits should be fully identified one by one in order to group them according to their quality. In the breeding process, the rabbit population can be divided into the following three categories according to quality. a. Core group. This is composed of rabbits with the best individual quality and excellent heredity in the whole rabbit population. After the core rabbit group is formed, the breeding work will be guaranteed. The vast majority of rabbits in the future will be supplied by the core rabbit population. b. Production group. After identification, all eligible rabbits are divided into human populations. In general, most of their offspring supply breeding rabbit farms or commercial rabbit farms. If offspring are found to have particularly good individual performance, they can also be reserved for reserve rabbits. c. Elimination of groups. Rabbits identified as having poor quality are all placed in the elimination group. These rabbits have no breeding value and can be transferred to commercial rabbit farms. 2 Maintain a certain amount of basic groups. In order to ensure the quality of rabbits, it is also important to maintain a certain number of basic groups in addition to improving feeding management and raising the level of breeding techniques. The size of the rabbit population is very related to the quality of the selected rabbits. If the rabbit population is large, there will be more chances when selecting rabbits so that the best quality rabbits can be selected as species; If the same number of species of rabbits is to be selected among the smaller rabbit populations, the chance of selection is small at this time, and in order to achieve a certain number of selections, inevitably there will be phenomena of insufficiency, and as a result, the quality of breeding rabbits will be reduced. Therefore, the degree of kinship within the group of rabbits rises faster than that of rabbits. In addition, there must be a certain number of male rabbits that are far apart from each other in the rabbit population in order to avoid unnecessary intimacy. 3 The age structure of the rabbit population. In a group of rabbits, it must be composed of rabbits of various ages. Although adult rabbits have the highest reproductive performance and production performance and should have higher proportions in rabbit populations, it should also be noted that in order to rapidly improve the quality of rabbit populations in breeder farms, it is necessary to emphasize generational renewal, which is Some poor quality adult rabbits and old rabbits were eliminated from the rabbit population, and some good quality rabbits were selected from the reserve rabbits for supplementation. In the age structure of the rabbit population in rabbit farms, young rabbits and young rabbits should also occupy a considerable proportion. How many reserve rabbits should be selected each year? This should be based on the specific circumstances of each field. In general, it is determined by the number of rabbits to be renewed each year in the rabbit population and the rate of retention. The so-called retention rate refers to the number of rabbits selected from the number of rabbits that are reserved, that is, the number of reserved rabbits/reserved rabbits is 100%. For example, if you choose to reserve 25 rabbits from 100 rabbits, the retention rate should be: That is, select 1 rabbit per 4 reserved rabbits. Therefore, the smaller the retention rate, the more reserved rabbits need to be identified for each type of rabbit selected, and therefore the quality of the selected breeding rabbits is also higher. In the rabbit farm, about 30% is updated every year. (2) Rex Rabbit Breeding 1 The significance of breeding. The so-called strains refer to descendants from the same ancestor within the breed. This group of descendants not only has good general traits, but also stands out particularly in one or a few traits. They maintain a certain degree of kinship and at the same time, they are in the nature of each other. It is similar to the characteristics. For example, in the case of rex rabbits, when the general performance is good, some hairs are very dense, and some have a good body shape and constitution. In this way, it is possible to use their respective advantages to cultivate different strains with large hair density, large body size, good constitution, and superior quality of skin sheet, such as hair-dense and bulky systems. Later, through cross-breeding, several excellent properties can be brought together, and due to the distant genetic relationship between strains, improper inbreeding can also be avoided. The strain has great significance in the breeding of improved varieties. Because all breeds of Rex rabbits are the result of a combination of several economical traits, such as the Rex Rabbit, large size, high hair density, and capillary; German Rex rabbits, large size, large hair density, slightly coarse hair; US Department of Rex rabbit hair Thin, small body, high reproductive rate. In addition, it is also affected by reproductive performance. Although the quality of the selected rabbits is generally good, it cannot be perfect. Some of them are more prominent in these traits, and some of them are more prominent in those traits. The number of individual rabbits of the above-mentioned type is rapidly expanded to become a rabbit group, i.e., a strain. By subsequent cross-breeding of these strains having different superior traits, it is possible to concentrate these excellent characteristics in the offspring, thereby maintaining And improve the quality of this species. In addition, strains also play a significant role in controlling relative mating within breeds. Although individuals within a strain often maintain a certain degree of kinship, the genetic relationships between breeds are generally far apart, so when breeds are established several After strains, the phenomenon of forced mating can be avoided. 2 breed breeding methods. a. "Faculty ancestors" construction method. This method firstly finds male bunnies with excellent phenotype and genetic properties in the rabbit population. As a “familiar ancestor†of the created strain, it strictly meets the requirements of the variety. It also has unique genetic stability and no hidden undesired genes. Then select 5 to 10 females that have no kinship and common characteristics to mate with them. In order to quickly consolidate the excellent characteristics of this type of male rabbit in the offspring, and to avoid the occurrence of inbreeding recession, moderate mating can generally be used. When this excellent breed male rabbit breeds a large number of offspring and a considerable number of individuals in the offspring have the same excellent characteristics of the male rabbit, the male rabbit and its superior offspring together constitute a strain. In order for this strain to continue, male rabbits with outstanding performance must be selected from its descendants as successors to the family. The basic work of breed breeding is still strict seed selection and selection, so the work can only be done when there are a large number of individuals within the strain. b. Subpopulation breeding methods. Also known as systematic breeding method, it is mainly based on phenotypic selection to establish strains. It is based on production performance and body appearance. Select the basic group. The basic group is composed of male and female males with excellent performance. These rabbits do not require the same phenotype, because they are selected by breeding rabbits with various advantages. Finally, it is possible to combine these advantages. Concentrated together to form a high product line. In order to prevent the rapid increase in pro-community during the establishment of the system, there must be a certain number of male and female rabbits in the basic group, of which no less than 10 male rabbits, and they are required to have no kinship between them, the number of female rabbits and male rabbits Keep it at 5 to 10:1. After the basic group is formed, it is locked and breeding, and a random mating method is carried out in the group so that each male rabbit and each female rabbit have a chance of mating. Later, in their descendants, the same number of excellent male and female rabbits were selected to form a new basic group, that is, one generation was replaced. Generally, the original basic group is counted as the zero generation, the new basic group composed of their descendants is a generation, and the new basic group composed later is the second generation and the third generation. Which generation is considered to be a finished product line depends on the specific situation. Generally speaking, it can be completed after five or six generations. This method is simple and easy to use and can be used in rural areas. If it is a rabbit breeder, the family will be able to take on the tasks of building breeding, and the environmental conditions will be the same, so the breeding effect will be better. c. In-transit building. It is to select rabbits with rich genetic basis and good quality. Through high inbreeding, additive gene effects are accumulated and non-additive effect genes are homozygous. Then, based on this selection and selection, breed into inbred lines. The advantages of in-situ construction are short time and significant effects; the disadvantages are that homozygous recessive genes may be homozygous and the introduced viability is reduced. 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