Author : Neramit Sookmanee

Summary : Three experiments were conducted to study molecular markers in swine. The first experiment delt with estimation of genetic variation between and among native swine in the Philippines and Thailand using Amplified Fragment Length Polymorphism (AFLP). Blood samples were also collected from 9 native pigs coming from UPLB-UA Farm and from 16 native pigs in 4 provinces of Thailand, namely: Nakornpathom, Nakornratchasima, Ubolratchatani, and Khon Kaen. The mixing of DNA genomics in the Philippine and Thailand population for 12 primer pairs AFLP produced 209 scored bands which ranged from 10 (Er+CGT/Ms+CAC and Er+CGT/Ms+CAA to 28 (Er+CAG/Ms+CAC). The similarity coefficient between the Philippines and Thailand population ranged from 0.67 (Er+CAG/Ms+CTG) to 0.91 (Er+CGT/Ms+CAG) which an average of 0.78. The Er+CAG and Er+CAT primer chosen to analyse five native pigs from UPLB-UA Farm were found to have similarity coefficient, ranging from 0.69 to 0.96. The similarity coefficient among Thailand native pigs ranged from 0.80 to 1.00. In the second experiment, the incidence of Malignant Hyperthermia (MH). Halothane (HAL) gene in Landrace breed from the Philippines and Thailand was studied using blood samples from forty six Landrace pigs coming from 4 farms in the Philippines and 89 Landrace pigs from 5 farms in Thailand. This study demonstrated that the DNA-based test for the Cytosine to Thymine mutation at nucleotide 1843 could be used for the diagnosis of the MH status pigs. The DNA-based test could distinguish three genotypes (NN, Nn, and nn). The most appropriate primer was 315 bps PCR products. The incidence of MH gene of Landrace pigs in Thailand was higher than in the Philippines with gene (n) frequency of 18 percent. The heterozygous carrier frequenncy (Nn) was 32 percent. The Belgian Landrace from the Philippines had the highest Nn frequency (50 percent) and gene (n) frequency of 25 percent while the Canadian Landrace from Thailand had the highest Nn genotypic frequency (50 percent). The Belgian Landrace had the highest gene (n) frequency (30 percent) among Landrace strains in the Thailand. The Taiwanese Landrace had the lowest in both Nn and n frequency. The third experiment was conducted to find the genetic diversity and estimate the genetic variation among Landrace strains from the Philippines and Thailand. Twelve primer combinations were selected for the AFLP production of the 353 fragments detected 14.16 percent were polymorphic. The number of polymorphic fragments varied from 0 (Er+ACC/Ms+ATG) to 9 (Er+TAC/Ms+CAG) with an average of 4.17 loci per primer pair. The primer pairs, Er+ACC/Ms+ACT, Er+ACC/Ms+ACT, Er+AAC/Ms+ACC, Er+CGT/Ms+AGG and Er+CGA/Ms+TAG were found to be informative markers. The average polymorphism in Philippines and Thailand landrace were 3.97 percent, 8.22 percent, and 3.40 percent for American, Belgian and Canadian Landrace, respectively. On the five primer pairs selected the total number of scored fragment was 98 of which 44.90 percent were polymorphic. The Er+AAC/Ms+ACC and Er+TAC/Ms+CAG had polymorphism higher than the rest of the primer pairs. The diversity among American, Belgian and Canadian Landrace were 1.17, 2.42 and 1.00 loci per pair, respectively. On the average diversity between Philippines and Thailand Landrace was 4.17 loci per primer pair. The American, Belgian and Canadian Landrace from the Philippine had 7.8, 4.4, and 1.40 loci per primer pair, respectively. On the other hand, the American, Belgian, and Canadian Landrace in Thailand had 5.4, 2.60, and 3.60 loci per primer pair, respectively.