| The complete mitochondrial D-loop region from 187 individuals in 18 Chinese cattle breeds, which include 5 northern breeds, 9 southern breeds, 3 Tibetan breeds and Germany Yellow Cattle(only 2 individuals), was sequenced and analyzed by PCR and sequencing technique. The results showed as follows:1. The region of D-loop in186 individuals in 18 breeds ranged from 909 bp to 913 bp, with the contents of 61.5% A+T and 38.5% G+C. And the length of one special sequence was 893 bp.2. There were totally 97 haplotypes sorted into 62 taurine ones, 34 zebu ones and a yak one. And there were 110 variation sites expanding from the start to the end of the D-loop region, with only 75 ones distinguishing taurine and 43 ones distinguishing zebu.3. The average haplotype diversity(Hd) was 0.926±0.016, the average number of nucleotide differences(k) was 23.116, and nucleotide diversity (π) was 0.02560±0.00034, all of which had shown very high genetic diversity in Chinese cattle breeds.4. In the Neighbor-Joining tree and network, 18 cattle breeds were mainly divided into two clades, Bos taurus(54.55%) and Bos indicus(45.45%), with an exception of CladeⅢof yak.5.With a software developed with Perl, the study for CladeⅢproved that Chinese Tibetan cattle had an introgression of yak maternally. It told that an emphasis should be placed on the origin study of Chinese cattle and this is the first time to detect yak lineage in Chinese cattle based on the complete D-loop sequence6. In Tibetan, zubu had been found with a large proportion in cattle. The rates of taurine and zebu were 64.3% and 35.7% in XigazêHumped cattle breed, and 50.0% and 50.0% in Apeijiaza cattle breed.Tibetan zebu appeared in I2 and SH2, and also all the haplotypes in SH2 appeared very distant from the core of I1, proving its special position in Chinese zebu. In the haplotype network of taurine, T2 had not been found in both Tibet taurine and Yunnan Zhaotong taurine. Both facets indicated that Tibetan cattle was an isolated type, not only for zebu but also for taurine. Yunnan Gaofeng zebu had almost the same pattern as Tibetan zebu, with an overlap in I2, being a cue to be of similar origin for both of Yunnan and Tibetan zebu, which was different from the other area in China. Combining with data of being lack of T2 in taurine, it was presumed that Tibet and Yunnan owned similar origin of cattle.7. In the haplotype network of zebu, there were two haplogroups I1 and I2. I1 had been divided into two sub-haplogroups SH1 and SH2. The most zebu in China lied in I1, only two haplotypes staying in I2.8. Here three haplogroups(T2, T3, T4) had been found in the network of taurine, with the most of T3(81.2%) for Europe origin, T2(8.9%) for Near East origin and T4(9.9%) for Northeast Asia origin. But T1 for Africa origin had not been detected.9. Chinese taurine migrated earlier than zebu in China, and also two hypotheses for the migrating routes had been developed: one for west-to-east route and the other for north-to-south route. No zebus were found in Chinese northern cattle breeds, and the proportions of zebu shrinked from south to north, proving the south-to-north route for zebu, with the origin place in Yunnan and Tibet nearby. Meanwhile, the two routes couldn't be ignored for taurine, with large possibility.
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