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Mitochondrial DNA diversity and origin of indigenous pigs in South China and their contribution to western modern pig breeds
WANG Chen, CHEN Yao-sheng, HAN Jian-lin, MO De-lin, LI Xiu-jin, LIU Xiao-hong
2019, 18 (10): 2338-2350.   DOI: 10.1016/S2095-3119(19)62731-0
Abstract139)      PDF in ScienceDirect      
Indigenous pigs in South China are valuable genetic resources with many specific and unique characters, which have played an important role in the establishment of some western modern pig breeds.  However, the origin and genetic diversity of indigenous pigs in South China have not been fully understood.  In the present study, we sequenced 534 novel mitochondrial DNA (mtDNA) D-loop and assembled 54 complete mitogenome sequences for all 17 indigenous pig breeds from Fujian, Guangdong, Guangxi and Hainan in South China.  These data were analyzed together with previously published homologous sequences relevant to this study.  We found that all 13 coding genes of the mitogenomes were under purifying selection, but ND1 had the most variable sites and CYTB contained the most non-synonymous SNPs.  Phylogenetic analysis showed that all indigenous pigs in South China were clustered into the D haplogroup with D1a1, D1b, D1c and D1e sub-haplogroups found to be dominant.  Haplotype and nucleotide diversities of D-loop sequences ranged from 0.427 to 0.899 and from 0.00342 to 0.00695, respectively, among which all pigs in Guangdong had the lowest diversity.  The estimates of pairwise FST, gene flow (Nm) and genetic distance (Da) indicated that most of these indigenous pig breeds differentiated from each other significantly (P<0.05).  Among the western modern breeds, Berkshire and Yorkshire had significant Asian matrilineal footprints from indigenous pigs in South China, especially the Spotted pigs distributed in Guangdong and Guangxi.  The neutrality test (Fu’s FS) indicated that indigenous pigs from Fujian and Guangxi had gone through recent population expansion events (P<0.05).  It is concluded that indigenous pigs in South China were most likely derived from the Mekong region and the middle and downstream regions of Yangtze River through Guangxi and Fujian.  Our findings provide a complete and in-depth insight on the origin and distribution pattern of maternal genetic diversity of indigenous pigs in South China.
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Effects of back fat, growth rate, and age at first mating on Yorkshire and Landrace sow longevity in China
HU Bin, MO De-lin, WANG Xiao-ying, LIU Xiao-hong, CHEN Yao-sheng
2016, 15 (12): 2809-2818.   DOI: 10.1016/S2095-3119(16)61381-3
Abstract1136)      PDF in ScienceDirect      
In the present study, genetic parameters for longevity and genetic correlations with back fat (BF), average daily gain (ADG), and first mating age (FMA) were estimated from 19 300 Yorkshire and 18 378 Landrace sows from 12 farms derived from one breeding system. General linear models (GLM) were employed to estimate genetic correlations with heritability (h2). Longevity was defined by six different parameters (i.e., traits) and heritability ranged from h2=0.13 to 0.16 (P<0.05) in both swine breeds. Genetic correlations between different longevity definitions were positive and high (r=0.79 to 0.99; P<0.05). BF exhibited low positive genetic correlations (r=0.12 to 0.15; P<0.05) with longevity traits identified in both pig breeds which were dependent on trait definition, whereas ADG and FMA showed weak negative genetic correlations with longevity traits. The influence of BF, ADG, and FMA on longevity traits was examined by dividing the production and reproductive traits into several numerical groups; the influence of each longevity trait was subsequently analyzed among the different groups. The results indicated BF was the best trait to improve longevity among BF, ADG, and FMA, which showed positive effects for almost all longevity traits. For Yorkshire sows, gilts with over 18 mm BF were most desirable; Landrace with 10.6–13 mm BF were suitable for longevity. ADG was not favorable for gilt selection, because the correlation between growth rate and longevity very low. For FMA, our results indicated gilts mating before 230 days exhibited a longer life span. Therefore, we suggest farmers should select for thicker back fat and mate at an earlier age to improve sow longevity.
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