?Selected new strains of Duroc by partial-closure selection on generation substitution. a base group was established in 1991. Each year 1 generation was selected, and so far 4 generation have been selected and tested.

• 杜洛克猪新品系采用不完全封闭的群体继代选育法选育，于1991年开始组建基础群，一年一个世代，至今已完成4个世代的测定与选择，各项性能指标已达到育种目标。