Research On The Optimization Of Breeding Schemes For Quality Pig

Optimization of breeding schemes for quality pig was studied through four parts: fixing on the breeding goal, constructing and optimizing crossbreeding system, optimizing breeding schemes for pure line breeding and reproduction population. Aim of this study was offering theory base and practice guarantee for quality pig breeding and production in China, and improving pork's competition power. Quality pig was that it has high yield, good quality and big safety. Concrete research method was: calculating economic coefficients of objective traits and simplified integrative breeding value of breeding goal for quality pig through constructing model based on balancing method and system analysis method, constructing and selecting the best crossbreeding system for quality pig through simulating biological economics process, optimizing breeding schemes of pure line breeding and reproduction population in crossbreeding system for quality pig by gene-flow method through fixing model, and putting forward other problems in breeding quality pig by referencing practice in swine production. The result is: 1, Integrated breeding value of quality pig should include five objective traits, that is litter size born alive, days at body weight 100kg, feed conversion efficiency, estimated lean meat percentage and content of intramuscular fat. Selective traits for that objective character should include litter size born alive, days at body weight 100kg, back fat alive, eye muscle alive and content of intramuscular fat. Marginal profits for the above five objective traits respectively are 8.06, -0.87, -86.32, 10.78 and 48.51. Goal traits for sire line in sire breed are not include litter size born alive. Marginal profits for all objective traits but litter size born alive in dam line of dam breed are 1/2 smaller than those in sire line of dam breed. Economic coefficient is equal to the product of marginal profit and expressed discounted value for objective trait. It was thought through analyzing simplified integrated breeding value that content of intramuscular fat, feed conversion efficiency, and estimated lean meat percentage used as objective traits in integrated breeding value was most significant. 2, In 10 crossbreeding systems, economic efficiency and meat quality were most excellent for Duroc ×(Large White ×specialized dam line B of Jihe White ), and combinations of three matched lines composed by two foreign pig breed and one Chinese cultivated pig breed containing Chinese local pig descent were most probably bred for quality pig. 3, When breeding schemes of pure line breeding and reproduction population in crossbreeding system were being optimized, breeding plan period 60 pig-years (1 pig year = 6 months ) was the best. At present status when other factors were fixed, the best proportion of breeding group in pure line breeding and reproduction population respectively was 0.160, 0.136 and 0.088 for sire line in sire breed, sire line in dam breed and dam line in dam breed, female/male ratio 20 for breeding group was the better, used period 2 pig-years for male was the best, increasing fee for trait testing would decrease breeding benefit. Size of the breeding group should not be very small and the number of male should not be very little, so as to preventing inbreeding depression. In the research limited scope, when the three factor were integrated optimized, the best situation, sequenced as breeding group proportion, used period of male and the end is female/male ratio, was 0.185, 2 and 25 for sire line in sire breed, 0.139, 2 and 25 for sire line in dam breed, and 0.104, 2 and 25 for dam line in dam breed. After integrated optimized, for sire line in sire breed, breeding benefit was increased by 127.03% and yearly genetical increase of integrated breeding value was improved by 49.43%, for sire line in dam breed, that was 119.95% and 47.79%, and for dam line in dam breed, that was 93.67% and 45.19%. 4, Other factors should be noted while breeding quality pig, such as sanitation and safe of pork, veterinary safe on pig farm, environmental protection, management on pig farm and improving meat quality by feed and nutrition method.