Abstract: Objectives To analyze the sequence of 5' end of mtDNA D-loop region of Tibet minipigs, Bama miniature pigs and Guizhou xiang pigs and WZS pigs，to investigate genetic differentiation and the phylogenetic relationship between mini-pigs and several other breeds of Chinese domesticated pigs. Methods The fragment of 5' end of D-loop region in four breed mini-pigs were amplified and sequenced, followed by being multiple alignment compared with each other，then variation sites and haplotype were made. Genetic relationship tree between mini-pigs and other China domestic pigs were established. Results Compared with Rongchang pig，704bp sequence at 5' end of the Tibet mini-pigs D-loop had 20 polymorphic sites which deduced 26 haplotypes. There were two mainly haplotypes which have three transform sites at 305，500 and 691，one is t，a，a，respectively; another is c, g, g , respectively. Bama miniature pigs, Guizhou xiang pigs and WZS pigs had 4，4 and 3 haplotypes, respectively. Tibet mini-pigs had close relation with domestic pigs in southwest China by using phylogenetic tree. Conclusions There were genetic differentiation in Tibet mini-pigs colony and had a closely genetic relationships with southwest Chinese domestic pigs. Bama miniature pig and Guizhou xiang pig and WZS pig had less genetic differentiation that may be the results of artificial selection.

Key words: Experimental mini-pig, mtDNA, 5' end of D-loop region, Comparative research