Selection of sub-populations to preserve with high priorities for the conservation of genetic diversity in the Japanese Black cattle population

自1991年牛肉进口限制自由化以来，日本国内高品质牛肉的生产得到了更多的重视，日本黑牛的肉质（特别是“牛肉大理石花纹”）通过育种动物的遗传评价系统得到了显着改善。然而，由于集中使用少数具有牛肉大理石花纹高遗传价值的品种，遗传多样性急剧下降是该品种日益严重的问题。在本研究中，为了保护日本黑人群体的遗传多样性，评估了需要优先保护的亚群（即地方菌株）。采用Weitzman方法和核心集方法对当地25个主要人群的家系和身体测量数据进行分析。两种方法的结果强烈表明，应优先保护中部地区的5个传统种群（兵库县、鸟取县、冈山县、广岛县和岛根县）和九州地区的3个区域性种群（大分县、宫崎县和鹿儿岛）。有研究认为，多系轮作配种可以有效地保护日本黑群体的遗传多样性。本研究的结果有望为旋转配合的应用提供基本信息。

Since liberalization of beef import restriction in 1991, domestic production of high-quality beef has received more emphasis in Japan, and meat quality (especially, ‘beef marbling') of Japanese Black cattle has been remarkably improved by the genetic evaluation system of breeding animals. However, due to the intensive use of a few sires with high genetic merit of beef marbling, drastic decline of genetic diversity is an increasing problem of this breed. In the present study, the sub-populations (i.e., local strains) to preserve with high priorities were assessed to conserve the genetic diversity in the Japanese Black population. Two different methods, i.e., the Weitzman's method and the core set method, were applied to the pedigree and body measurement data obtained from 25 major local populations. The results from the two methods strongly suggest that the five traditional populations in Chugoku district (Hyogo, Tottori, Okayama, Hiroshima and Shimane) and the three regional populations in Kyusyu district (Oita, Miyazaki and Kagoshima) should be preserved with high priorities. It has been proposed that rotational mating system with several sire lines could be efficient for the conservation of genetic diversity in the Japanese Black population. The result obtained from this study is expected to give basic information for the application of the rotational mating.