• Asian-Australasian Journal of Animal Sciences
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• v.13 no.9
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• pp.1193-1195
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• 2000

The polymorphisms of six microsatellites were investigated in four indigenous pig breeds (Erhualian, Tongcheng, Qingping and Wannanhua) and three introduced breeds (Large White, Landrace and Duroc) in China, and the genetic variations within and among populations were analyzed. The results showed that genetic diversity of Chinese indigenous pig breeds is higher than that of the introduced pig breeds. The clustering of seven breeds is consistent with their geographical distribution approximately. Estimated time of breed divergence ranged from 653 to 1856 years.

• Asian-Australasian Journal of Animal Sciences
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• v.17 no.4
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• pp.441-444
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• 2004

The genetic diversities and relationships of 10 Chinese indigenous pig breeds and three exotic pig breeds have been evaluated using 26 microsatellites recommended by the Food and Agriculture Organization & the International Society of Animal Genetics (FAO-ISAG). The allele frequencies, genetic heterozygosity (H) and polymorphism information content (PIC) have been calculated. The results showed that genetic diversity of Chinese indigenous pig breeds is higher than that of the introduced pig breeds. The clustering of 10 breeds is generally consistent with their geographical distribution.

• Asian-Australasian Journal of Animal Sciences
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• v.16 no.2
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• pp.161-164
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• 2003

The polymorphism of the growth hormone gene in 12 pig breeds (total n=475) was detected by PCR-Apa I-RFLP, and allele A (449 bp, 101 bp and 55 bp) or allele B (316 bp, 133 bp, 101 bp and 55 bp) were observed. In these pig breeds, we found that European pig breeds had high frequencies of allele B, while Chinese native pig breeds had high frequencies of allele A. In addition, the role of porcine GH was investigated in 117 Nanchang White pigs and 361 Large Yorkshire pigs. Eight traits about growth and carcass were recorded for analyzing associations between GH gene polymorphism and performance quantitative traits. In the Nanchang White pigs, no significant difference was observed between different genotypes and different growth and carcass traits. In Large Yorkshire pigs, those with BB genotype had more lean percentage than pigs with AA genotype (p<0.05). Based on these results, we conclude that the GH locus should be further investigated in commercial breeds to determine its suitability for use in marker-assisted selection programmes.

• Asian-Australasian Journal of Animal Sciences
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• v.16 no.7
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• pp.939-945
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• 2003

Seventeen Chinese indigenous pig breeds and three introduced pig breeds had been carried out by means of vertical polyacrylamide gel electrophoresis (PAGE). According to the results, eight serum protein loci were highly polymorphic except Pi-2 and Cp. The polymorphism information content (PIC) of Hpx was the highest (0.5268), while that of Cp was the lowest (0.0257). The population genetic variation index showed that about 84% genetic variation existed in the population, and the rest of 16% distributed between the populations. The genetic variation of Yimeng black pig and Duroc were the highest and the lowest, respectively. The genetic variation of Chinese indigenous pig breeds was much more than that of exotic groups. Genetic distance results showed that Chinese indigenous pig breeds were classified into four groups with the three introduced pig breeds clustered into another group. The results also supported the geographic distribution of Chinese indigenous pig breeds in certain extent.

• Asian-Australasian Journal of Animal Sciences
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• v.27 no.9
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• pp.1263-1269
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• 2014

Comprehensive information on genetic diversity and introgression is desirable for the design of rational breed improvement and conservation programs. Despite the concerns regarding the genetic introgression of Western pig breeds into the gene pool of the Korean native pig (KNP), the level of this admixture has not yet been quantified. In the present study, we genotyped 93 animals, representing four Western pig breeds and KNP, using the porcine SNP 60K BeadChip to assess their genetic diversity and to estimate the level of admixture among the breeds. Expected heterozygosity was the lowest in Berkshire (0.31) and highest in Landrace (0.42). Population differentiation ($F_{ST}$) estimates were significantly different (p<0.000), accounting for 27% of the variability among the breeds. The evidence of inbreeding observed in KNP (0.029) and Yorkshire (0.031) may result in deficient heterozygosity. Principal components one (PC1) and two (PC2) explained approximately 35.06% and 25.20% of the variation, respectively, and placed KNP somewhat proximal to the Western pig breeds (Berkshire and Landrace). When K = 2, KNP shared a substantial proportion of ancestry with Western breeds. Similarly, when K = 3, over 86% of the KNP individuals were in the same cluster with Berkshire and Landrace. The linkage disquilbrium (LD) values at $r^2_{0.3}$, the physical distance at which LD decays below a threshold of 0.3, ranged from 72.40 kb in Landrace to 85.86 kb in Yorkshire. Based on our structure analysis, a substantial level of admixture between Western and Korean native pig breeds was observed.

• Asian-Australasian Journal of Animal Sciences
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• v.19 no.11
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• pp.1541-1545
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• 2006

The polymorphism of insulin-like growth factor I receptor (IGFIR) gene in 12 pig breeds (total n = 593) was detected by PCR-SacII-restriction fragment length polymorphism and allele A (379 bp) or allele B (235 bp and 144 bp) observed. In the studied breeds, it was found that European pigs principally carried allele A, while Chinese native pig breeds principally carried allele B. In addition, the role of pig IGFIR was investigated in 156 Wanbai pigs and 212 Large Yorkshire pigs. Growth related variables including body weight at birth, 2-, 4- and 6-mo of age and backfat thickness and lean percentage estimated by ultrasonography at 6-mo of age were recorded in analyzing the association between IGFIR gene polymorphism and growth traits. AA-genotype pigs exhibited greater (p<0.05) body weights (BW) at birth, 2- and 6-mo of age, but not at 4-mo of age, than those of the BB-genotype in Wanbai and Yorkshire breeds. Moreover, in the Yorkshire breed, AA-genotype pigs had less backfat thickness (p<0.05) and greater lean percentage (p<0.01) than the BB genotype. Based on these results, it is necessary to do more studies on IGFIR before introducing the IGFIR locus into breeding programs.

• Asian-Australasian Journal of Animal Sciences
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• v.28 no.4
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• pp.457-466
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• 2015

Taoyuan pig is a native Taiwan breed. According to the historical record, the breed was first introduced to Taiwan from Guangdong province, Southern China, around 1877. The breed played an important role in Taiwan's early swine industry. It was classified as an indigenous breed in 1986. After 1987, a conserved population of Taoyuan pig was collected and reared in isolation. In this study, mitochondrial DNA sequences and 18 microsatellite markers were used to investigate maternal lineage and genetic diversity within the Taoyuan pig population. Population differentiation among Taoyuan, Asian type, and European type pig breeds was also evaluated using differentiation indices. Only one D-loop haplotype of the Taoyuan pig was found. It clustered with Lower Changjiang River Basin and Central China Type pig breeds. Based on the polymorphism of microsatellite markers, a positive fixation index value ($F_{IS}$) indicates that the conserved Taoyuan population suffers from inbreeding. In addition, high $F_{ST}$ values (>0.2105) were obtained, revealing high differentiation among these breeds. Non-metric multi-dimensional scaling showed a clear geometric structure among 7 breeds. Together these results indicate that maternally Taoyuan pig originated in the Lower Changjiang River Basin and Central China; however, since being introduced to Taiwan differentiation has occurred. In addition, Taoyuan pig has lost genetic diversity in both its mitochondrial and nuclear genomes.

• Asian-Australasian Journal of Animal Sciences
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• v.33 no.2
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• pp.212-218
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• 2020

Objective: Agu pigs are indigenous to the Okinawa prefecture, which is the southernmost region of Japan. Agu pigs were exposed to a genetic bottleneck during the 20th century, due to the introduction of European pig breeds. The objective of this study was to elucidate the genetic structure of Agu pigs and to determine their relationships with those of five European breeds, two Chinese breeds and Ryukyu wild boar using microsatellite markers. Methods: A total of 203 DNA samples from 8 pig breeds were used in this study. Genotyping was performed using 21 microsatellite markers distributed across 17 chromosomes. Results: Numbers of effective alleles in Agu pigs were fewer than in European breeds and Ryukyu wild boar. Among domestic pigs, Agu pigs had the lowest heterozygosity (0.423) and highest inbreeding coefficient (F_IS = 0.202), indicating a severe loss of heterozygosity in Agu pigs possibly due to inbreeding. Neighbor-joining tree analysis was performed based on Reynolds' genetic distances, which clustered Agu pigs with Duroc pigs. However, principal component analysis revealed a unique genetic position of the Agu pig, and the second principal component separated Agu pigs from all other breeds. Structure analysis with the optimal assumption of seven groups (K = 7) indicated that Agu pigs form an independent cluster from the other breeds. In addition, high and significant F_ST values (0.235 to 0.413) were identified between Agu pigs and the other breeds. Conclusion: This study revealed a substantial loss of genetic diversity among Agu pigs due to inbreeding. Our data also suggest that Agu pigs have a distinctive genetic structure, although gene flows from European breeds were observed.

• Journal of Animal Science and Technology
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• v.55 no.5
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• pp.467-473
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• 2013

This study compared the pork quality and muscle fiber characteristics between the Jeju black pig (JBP) and domesticated pig breeds, including three-way crossbred (Landrace ${\times}$ Yorkshire ${\times}$ Duroc, LYD), Berkshire (B), Duroc (D), Landrace (L), Meishan (M), and Yorkshire (Y) pigs. JBP had the lowest carcass weight among the pig breeds (p<0.05) and its NPPC marbling score was lower than the other domesticated pig breeds (p<0.05), except for M. M had the highest value for backfat thickness among the pig breeds (p<0.05), whereas its NPPC marbling score was the lowest (p<0.05). The pH values were higher in JBP and B at 45 min and 24 h postmortem, respectively, but LYD and M had the lowest pH values at 45 min and 24 h postmortem, respectively (p<0.05). M had a higher lightness and lower redness than the other breeds (p<0.05). Moreover, M had the highest drip loss among the pig breeds (p<0.05), whereas D had the lowest drip loss and the highest redness (p<0.05). In terms of muscle fiber characteristics, JBP and LYD had the largest type IIB fibers (p<0.05). The fiber number and area composition of type I fibers were higher in JBP than the others (p<0.05) however type IIA fibers were lowest in JBP among the pig breeds (p<0.05). Overall, our results indicate that JBP provided better pork quality compared with M, but the carcass trait and pork quality of JBP were not better than LYD and D, respectively.

• Animal Bioscience
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• v.34 no.7
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• pp.1123-1133
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• 2021

Objective: Shandong indigenous pig breeds are important Chinese pig resources. Their progressive population decline in recent decades has attracted attention towards their conservation. Conservation genetics of these indigenous breeds are essential for developing a conservation and utilization scheme. Methods: A high-density single nucleotide polymorphism (HD-SNP) chip-based comparative analysis of genetic characteristics was performed for seven Shandong indigenous pig breeds in the context of five Western commercial breeds. Results: The results showed that Shandong indigenous pig breeds varied greatly in genetic diversity, effective population size, inbreeding level, and genetic distance with the Western commercial breeds. Specifically, Laiwu and Dapulian displayed low genetic diversity, and had a genetically distant relationship with the Western commercial breeds (average F statistics [F_ST] value of 0.3226 and 0.2666, respectively). Contrastingly, the other five breeds (Yantai, Licha, Yimeng, Wulain, and Heigai) displayed high genetic diversity within breed and had some extent of mixture pattern with the Western commercial breeds, especially Duroc and Landrace (F_ST values from 0.1043 to 0.2536). Furthermore, intensive gene flow was discovered among the seven Shandong indigenous breeds, particularly Wulian, Licha, and Heigai, as indicated by the large cluster formed in the principal component analysis scatterplot and small population differentiation (average of 0.1253) among them. Conclusion: Our study advances the understanding of genetic characteristics of Shandong indigenous breeds and provides essential information for developing an appropriate conservation and utilization scheme for these breeds.