Establishment Of Cross-breeding System Among Huanong-Wenshi Well-bred Pigs Of Guangdong Province

The decision of enhancing the swine-raising industry was bought out by Guangdong Huanong-wenshi Company in 1998, which would supply 1,000,000 commercial pigs and 50,000 pigs to the market, and in order to achieve the plan, a complete crossbreeding system of well-bred boars has to be established as the fundamental base.Many pig breeds have been involved in this breeding system, such as new Danish Landrance and old Danish Landrance, new Canadian Yorkshire, Taiwan's Duroc and American Duroc and French Pietrain, which were from our company,other four original pig farms in China and original pig farms in FranceOpen-population selection from generation to generation was done, and so did the vast measurement of the productive performance. Selection, cultivation of the nuclear herd was carried on by stage selection, BLUP evaluation index, comprehensive evaluation on the spot and selected mating, furthermore, the ESR gene in dam line and HAL gene in sire line was used for MAS (Markers-Assisted Selection). Finally, four different specialized strains were established.After measuring the combining ability, the specialized strains were divided into two specific dam lines (HN151, HN161) and two sire lines (HN111, HN121). The aims were to improve carcass traits and growth traits in sire lines whose heritability was high, reproductive performance in dam lines was favored. The four-line cross system was the best for commercial pigs after evaluating each multilane cross system.The alleles A and B at locus of ESR gene distributed differently in the three strains, the gene frequency of A was 0.96 in HN121, 0.91 in HN151 and 0.76 in HN161 respectively. The boars were selected by the genotype of HAL by PCR-RFLP; the frequency of the stress gene HAL was low enough to meet the breeding needs.After 6 years selection, the main economic traits of the specialized lines HN121, HN151 and HN161 were mostly higher than the demands in the breeding project. The variance of phenotype value of each trait was low; litter size was 9.36, 11.17 and 11.22, respectively. The days to reach 100kg were 166.17, 156.56 and 156.78 days, respectively.. The backfat thickness after adjustment to 100kg was 14.61, 14.98 and 14.58mm. After adaptation of the specialized line HN111for three years, the French original boars and sows were excellent in commercial performance; the backfat thickness after adjustment to 100kg was 12.97mm on average, the average days to reach 100kg was 159.05, the uniformity of conformation was high.Among the two dam lines, HN161 was selected as female parents of dam lines and HN151 as the male parents of dam lines. And when the female parents were limited, some sows of HN151 were also selected as candidate female parents of dam lines. Among the two sire lines, HN121 was chosen as male parent of dam line, and HN111 as male parent of sire line to produce the boars line HN212 which were in great body type, well developed muscle and high lean percentage. The days to reach 100kg of HN212 were 155.1, which was the shortest one. The backfat thickness was 13.08mm, and the feed conversion rate was 2.52. The integrated commercial indexes of HN111 were higher than HN212, and the latter had superiority in anti-stress, so HN212 was adapted to apply in the humid and fuggy south China.The four-line cross system had higher performance than the traditional three-line cross system, such as growth, feed conversion rate and lean percentage etc. The days to reach 100kg of HN401 were 145.1, the backfat thickness alive was 13.19mm and the feed conversion rate was 2.36. According to the examination of Guangdong mensuration center, the meat quality was more excellent, the meat color was 3.4, the meat marbling was 2.4 while PSE and DFD meat free. The carcass performance was fine, lean percentage, average backfat thickness, eye muscle area and the ham ratio was 67.21%, 17.6mm, 52.84cm~2, 32.6% respectively.There is an obvious hybrid effect of four-line cross system.After 6 years hard work, the high quality swine breeding system was completed. There were 1120 basic sows in the original pig farms, 3750 basic sows, grandparent farms which could provide 4870 pure sows and 60,000 hybrid sows that would give birth to 1,300,000 commercial stocks. High economical effects and social effects were gained. 3,000 boars and 800,000 commodity pigs were sold in 2004, the production value was nearly 900 million RMB with 150 million RMB benefit of the enterprise, 100million RMB benefit of the farmers and 5,000 RMB customer benefit.