Examination Of The Halothane Gene For Porcine Breeding Stock In Shanghai Area

The halothane gene is one of the early-detected genes that influence porcine meat quality and located on the chromosome 6, its recessive homozygote is associated with increased susceptibility to Porcine Stress Syndrome.The halothane genotype of the main pig-breeding farm from the year 2003 to 2005 in Shanghai area was detected by the PCR-RFLP technique in this study, the study has included 2128 breeding pigs from eight breeds, such as Large white, Landrace, Duroc, Shanghai white, Pudong white, Shawutou, Meishan, and Fengjing. The results are as following:1,From the year 2003 to 2005, the halothane genotype frequency of homozygous normal(NN), heterozygous animals(Nn) and homozygous halothane gene(nn) was 88.82%, 10.86% and 0.32% respectively in the main pig-breeding farm in Shanghai area, and the halothane gene frequency of n and N was 5.75% and 94.25% respectively. The halothane gene frequency of the year 2003,2004 and 2005 was 3.89%, 6.24% and 9.64% respectively, and with the annual increase of 60.41% and 147.81% for 2004 and 2005 respectively.2,From the year 2003 to 2005, the halothane genotype frequency of homozygous normal(NN), heterozygous animals(Nn) and homozygous halothane gene(nn) was 87.89%, 11.80% and 0.31% respectively for the early imported population of Large white, Landrace and Duroc, and 95.62%, 4.38% and 0% for the new imported population, and the halothane gene frequency of early vs. newly imported population for n and N was 6.21% vs. 2.19% and 93.79% vs. 97.81% respectively, and the n gene frequency of early imported population is 183.56% of that of the new imported population, this result suggested that the early imported population is probably a main way leading to the gradual increase of halothane gene among the pig-breeding farm in Shanghai area for the past years.3,From the year 2003 to 2005 in the pig-breeding farm in Shanghai area, the Duroc breed has the highest genotype frequency of heterozygous animals(Nn) and homozygous halothane gene(nn),than followed by the Large white and Landrace, these two breeds have only very lower frequency of heterozygous animals, and no homozygous halothane animals. Moreover, among the five lines in Duroc breed in Shanghai, the first three highest lines for halothane gene frequency are Taiwan, Taiwan-American and American line with a 15.58%, 10.16% and 3.18% respectively.4,In addition, there are a certain percentage of Nn genotype and in genotype in the old American and Denmark Line breed, while the newly introduced New American line and New Denmark line have only homozygous halothane normal genotype (NN), and no Nn and nn genotype.5,From year 2003 to 2004, the halothane genotype frequency of homozygous normal(NN), heterozygous animals(Nn) and homozygous halothane gene(nn) in Shanghai White line pigs are 92.42%, 6.06% and 1.52% respectively, and the halothane gene n and N are 4.55% and 95.45% respectively.6,In contrast, 4 excellent native breeds of Pudong white, Shawutou, Meishan and Fengjing in Shanghai are all homozygous halothane normal (NN) animals, it has indicated that the 4 native breeds all have good meat-quality traits.In conclusion, we should reduce the halothane gene frequency among the breeding populations, and eliminate all homozygous halothane gene of Duroc breeding pigs, control the service of the heterozygous pigs (Nn), and in the same time we should also reduce the Nn and nn genotypes in Landrace and Large white, therefore we can produce the safe and excellent commercial pigs by the three way hybridization model of "Duroc×Landrace×Yorkshire" in Shanghai area.