Concept of pure breeds and breeders becoming extinct 纯种和纯种育种者的概念逐渐消失 Specialized Sire Dam lines 专门化 父系和 母系 Selection for. growth Litter size carcass Growth carcass 选择 生长和胴体产仔数, 生长和胴体Concept of pure breeds and breeders becoming extinct! 纯种和纯种育种者的概念逐渐消失 Specialized Sire & Dam Lines 专门化 父系 和 母系 Selection for: Growth Litter size, & carcass Growth & carcass 选择: 生长和胴体 产仔数, 生长和胴体