| This paper involves two studies: (1) Study on the breeding goals for multiple crossbreeding system of CRP; (2) Study on the optimization for breeding programs for multiple crossbreeding system of CRP.In this study of breeding goal, a model integrated with difference method and system analysis was used to calculate the marginal profits of the traits which included number born alive (NBA, pig), adjusted 21-days litter weight (LW21,kg), piglet survival rate(PLSR%,%), feed gain ratio (F/G, kg/kg), average daily gain (ADG, g), estimated lean meat percentage (LEAN%,%), day to 100 kg (D100, day), meat quality index (MQI,%) and backfat(BF, cm) in three breeding lines. The results showed that in the situation of predicted market and production condition, the marginal profits for A line were 2. 51, 1.14, 0.10, 0.15, -48.41, 7.42, -1.02, 0.99 and -10. 49 RMB respectively, for C line were 1.43, 0.58, 0.06, 0.09, -24.73, 5.46, -0.55, 0. 55 and - 5.62 RMB respectively, for B line were 2. 35, 0. 64, 0. 05, 0.11, -27. 61, 4.17, -0. 52, 0. 55 and - 6. 70 RMB respectively. By adjusted with the genetic standard deviation, the relative economic weights for A line were 6.29, 8.29, 0.63, 11.90, -12.10, 11.13, -13.26, 2.22, and - 5. 33 RMB respectively, for C line were 3. 58,4.19,0. 35,6. 81, -6.18, 8.19, -7.10, 1. 24 and - 2. 86 RMB respectively, and for B line were 5.87,4.64, 0. 28, 5.12, -6. 90,6. 25, -6. 75,1. 24and - 3. 40 RMB respectively, by the analysis for simplified total breeding value, D100 which was involved in the total breeding value was most meaningful. While total breeding value included LW21, D100, ADQ and BF, it had a high accuracy. The correlation between simplified breeding value and whole total breeding value was 0. 9935. By the optimization for selection index, while the selection index only included ADG and BF, it had a high correlation (0. 7164) with total breeding value. By involving all eight traits, the correlation was 0.7728.75For the Optimization of present breeding programs of multiple crossbreeding system of CRP, A special PC-program ZPLAN was modified and adapted to particular situation . The method to improve present breeding programs were proposed. The influence of some control factors on breeding gain and breeding profit was studied on the base of optimum breeding programs. These factors were different population size, production lifetime of boar and sow, ratio of female/male in the production system, the test plan of genetic evaluation on the breeding values, Results involved:(1) The present breeding program can gain better breeding profits, but not reach the optimum breeding efficiency in proportion of herd, ratio of female/male and test plan. The programs which production life time of boar and sow in three breeding lines was one year, Proportions of B line, C line, A line, GP and PS were 1%, 0.5%, 1%, 7.5% and 90%, Ratio of female/male in three breeding lines, GP and PS were 10,30 and 40,Pigs for replacement in three breeding lines were all tested, and three males was tested per litter, can reach highest genetic gain and breeding profits.(2) Under the condition of unchanging total population size, increasing the population proportion of breeding lines could improve genetic gain per year, but to breeding profits, increasing faster in earlier than later. While proportion of A, C and B line were 1%, 0. 6% and 1. 2%, breeding profits would reach the most.(3) Increasing production lifetime could prolong generation interval, which increased selection intensity but decreased genetic gain per year and breeding profits. When the lifetime of boar and sow was one year, the breeding profits attached the most.(4) Increasing ratio by female/male in three breeding lines could increase breeding return, decrease breeding cost and increase breeding profits. The influence of sex ratio to breeding profits was most in B line, the latter was in C line and A line.(5) Increasing the proportion of tested population in three breeding lines could improve genetic gain and increase breeding profits. T...
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