The genetic trends of reproduction traits and production traits were favorable. The genetic trends of TNB, NBA, LBW for Yorkshire, Landrace and Duroc were 0.0038, 0.0583, 0.0677, 0.0024, 0.0359, 0.0235, 0.0032, 0.0421, 0.0187, respectively.

• 各性状的遗传趋势：繁殖性状TNB、NBA、LBW的遗传趋势大约克、长白、杜洛克分别为0.；0038、0