New Primitive Marking (Bider) in Mongolian Native Horse and Equus przewalskii

Abstract

The incidence of Bider (Bi marking) in Mongolian native horses was 0.010, and that according to districts was the highest (0.032) in Tov Aimag. Bi marking was frequently observed in bay (0.482) and chestnut horses (0.351), and was also observed in gray and roan horses. The incidence of Bi marking was high (0.842) in horses with a dorsal strip (DS) as a primitive marking. In 164 Equus przewalskii, the incidence of Bi marking was 0.396, which was about 40 times the incidence in Mongolian native horses. Bi marking was observed in both males and females in the two species, showing autosomal inheritance. Analysis of the mode of inheritance based on the incidence of Bi marking in foals according to various crossing combinations showed the complete dominance of Bi marking in both species. Thus, it was concluded that Bi marking occurs in Bi/Bi and Bi/- genotypes. This Bi marking differs from DS, leg stripes (LS) and shoulder stripes (SS), and is considered to be a type of primitive marking peculiarly occurring in Mongolian native horse and Equus przewalskii. The high incidence of Bi marking in Equus przewalskii (0.396), and the results of crossing between Mongolian native horses and Equus przewalskii performed in Mongolia, suggest introgression of the Bi marking gene from Equus przewalskii to Mongolian native horses.