The result of the analysis by SmaI-RFLP shows that: AA, AB genotype frequency of Mai-wa yaks is 0.5667, 0.4333 respectively, and that of Jiu-long yaks is 0.8387, 0.1613 respectively, and no BB genotype is observed.

• 两牦牛品种表现为从和AB两种基因型；其中九龙牦牛AA、AB基因型频率分别为0.；8387、0