In goats belonging to the different breeds and sub breed, the genetic polymorphism at the determinant locus of blood potassium was revealed by flame spectrophotometer method. The kalemic systems in those breeds were characterized by a polymorphism of middle level due to the existence of the two phenotypes and of three genotypes. The polymorphic character of this system is given by the distributional discontinuity of potassium ions in whole blood; the discontinuous space range were 10-34 m eq/L in the Mongolian native, 0.38-20.3 m eq/L in the Govigurbansaihan and 10.27-15.8 m eq/L in the AltainUlaan breeds.The animals with potassium ion concentration below the discontinuity space are of LK type (with low potassium) and those with ionic concentration above the discontinuity space are of HK type (with high potassium). The blood potassium level is determined by two alleles; KL and Kh, being in incomplete dominance relationship; the allele KL, responsible for low potassium, is dominant compared to its recessive Kh allele which causes high levels of blood potassium. These two alleles at the Ks locus, located on an autosomal chromosome, determine three genotypes; dominant homozygote (KLKL), heterozygote (KLKh), and recessive homozygote (KhKh). In the Mongolian native breed, the allele Kh was less frequent (20%) than its dominant KL (80%), in the Govi Gurban Saihan breed,and the frequency of the alleles were also 5 and 95%, respectively. The phenotype LK (80-100%) achieved a much higher frequency than the phenotype HK (5-20%) in those breeds. Consequently, the recessive homozygosis and heterozygosis recorded an equal frequency (50%, 50%) in the Mongolian native breed, and the frequency of recessive homozygosis were slightly higher than heterozygosis (66%>34%) in the Govi Gurban Saihan.
Key words: Blood potassium, genetic polymorphism, adaptation, goat.