小型ヤギいわゆるシバヤギの遺伝子構成

Genetic surveys were carried out on the miniature “Shiba” goats which have been raised in Nagasaki Prefecture, Japan. Recently, in the prefecture the number of “Shiba” goats has been markedly decreased to totally about 190 which are kept now only in two towns. Morphological genetic traits were observed to have been coming homogenous in Nagasaki Prefecture, and homogeneity of the traits in the colonies kept in National Institute of Animal Industry and in Stock Farm of University of Tokyo, especially in the latter, was remarkably high. The “Shiba” goats have white coat color, horns and supernumerary teats, but not wattles. Electrophoretic examinations of genetic variations at 27 blood protein loci revealed that variability in the “Shiba” goat populations were lower than that of the Japanese Saanen breed, and that the amount of gene flow from the Saanen breed into the “Shiba” goats was estimated to be smaller than into the present-day Okinawa meat goats. The genetic variability of the colony in Stock Farm of University of Tokyo was observed to be conspicuously low. From the results of pedigree analysis such a decay of genetic variability was postulated to come about from unavoidable inbreeding resulted from smallness both in numbers of foundation animals and in effective population size of the colony.