| Swine production is the main industry of the development of animal production in Mudanjiang city. It takes very important roles in developing village economy and enriching the peasants. It becomes more and more important to study the breeding system of three-breed cross in order to improve the quality of our city's pigs and make local swine industry prosper.In the experiment the nucleus population is composed of Landrace, Yorkshire and Duroc of Dawan Breeding Pig Farm in Mudanjiang city. The method of Closed-Nucleus population Selection with Not Overlapping the Generations (CNS-NOG) has been used for these purebred pigs with modern genetic theory. In the CNS-NOG the first thing is building up the nucleus population, then closing the nucleus herd and selecting the breeding stocks not-overlapping the generations, taking up the early selection method, having seed stock from the first litter, using the complex selection index method, mating the same amount of sows for different boars, keeping out sib and half-sib mating. The quality of the pure breed hogs has been improved by this selection and also have supplied with the ideal breeding material for the following crossing. By the experiment and other research results of in-broad or out-broad experts, we got the following results that the DLY cross combination is the best one compared with others.The three-breed cross breeding system is based on the purebred selection with the crossing method for the aim of producing the crossbred lean finishing pigs. In the experiment the crossing is based on Landrace as the sire line and Yorkshire the dam line or Landrace as the dam line and Yorkshire the sire line, and the produced cross female progenies are mated by Duroc as the terminal sire to produce the lean market hogs.In the production system Dawan breeding pig farm as the nucleus herd is the head of the system, producing and spreading the two-breed cross sows to the parent farms in the counties, and in each county the parent farms, as the second centre of spreading the crossbred sow, produce the market pigs for marketing farms or farmers.After the four years selection several performances have been improved. The litter sizes of Landrace and Yorkshire have reached 11. 05 and 11. 06 heads/litter. The litter size of two -breed cross sows is 12. 02 heads/litter. The daily gain is 762. 64g, 818. 49g, 827.00g and 910.00g respectively for Landrace, Yorkshire, Duroc and the three-breed cross finishing pigs and the feed conversion is 2. 80:1, 2. 78:1, 2. 71:1 and 2. 70: 1 respectively.The three-breed cross breeding system has been set up in our city. It has become the reasonable distribution of nucleus farm, grand-parent farm, parent farm and marketing farm. There are 369 parent farms or farmers of 15 heads of two -breed cross sows in our city, it is distributed in 7 counties of our city, and 340 thousand heads of three-breed cross market hogs have been produced, which is 66. 7% of total output of market hogs of our city.The great economic benefits have been reached after the three-breed cross breeding system had been set up. The total output of production value is 716 million, the economic benefits is 280 million, the increases of output value is 108 million, and the increases of economic benefits is 139 million.The following much great social benefits have been gotten: ideal economic benefits of the three-breed cross production system, the market being prospered, improving the commercial communication, good for reforming the village production structure, taking the key role in speeding developing the main industry, and supplying up with more job opportunity for village left labours and job-lost workers in our city.In the experiment the movable model of the three-breed cross production system, which can produce 500 thousands, 600 thousands and 700 thousands of lean market hogs every year in Mudanjiang city, has been set up.Master Candidate:Cui YaruMajor:Animal Nutrition and Feed ScienceSupervisor:professor Wei Guosheng... |
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