The so-called three-way crossbreeding of pigs refers to the use of two breeds for a single cross, followed by the second hybrid of a F1 hybrid sow and a third breed boar, and finally the three-way hybrid as a commercial pig. Ternary hybridization, because of its greater use of genetic complementarity and the heterosis of reproductive performance of hybrid sows, has been widely used in domestic and international commercial pig production. 1. Selection of species for reserve boars When carrying out three-way crossbreeding, the first male parent should choose breeds with superior reproductive performance and meat production performance, such as Changbai, Yorkshire, etc.; the terminal male parent should select excellent meat production performance. The species with lower reproductive performance. Such as Duroc, Hampshire and so on. 2. Selection of reserve boar individuals Reserve boars should have the following conditions: 1 good shape, strong physique. The reserve boar has a good combination of shoulders and chests, a moderate size of the abdomen, a flat back, well-kept legs, and a firm, compact body. A phylogenetic review confirmed that her ancestors or siblings had no genetic disorder. Appearance has the typical characteristics of the variety. 2 Rapid growth and development, excellent carcass traits. The selection can be based on the performance of the reserve boar's own score and the compatriot's performance for the fattening test. 3 Healthy reproductive function. To check the development of boar testes requires good growth, the same size, neat symmetry, feel solid but not hard to feel, should not cryptorchidism, monotesticular, hernia and foreskin expansion and other diseases. 3. Selection of gilts Reserve gilts should have the following conditions: 1 fast growth. To choose individuals and their siblings with fast growth and high feed utilization. Before the restriction of feeding, it is necessary to refer to the results of their own, but also refer to the results of compatriots. After the restriction of feeding, reference is made to the results of compatriots used for finishing. 2 high reproductive performance. The gilts are to select the offspring of high-yield sows with a large number of calves, a high rate of rearing, and major weaners. The external genital organs develop normally, the estrus cycle is regular, and the estrus symptoms are obvious. 3 typical body appearance characteristics. The coat color, head shape and ear shape have corresponding typical characteristics. Have enough nipples and neatly arranged. 4. Selection of breeding boar sources In actual production, the majority of breeding mother pigs only breed boars of a single species. The best way to solve the problem of less boar varieties is to use artificial insemination techniques.
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