CM 7.0 Selection for high fat 6.5 6.0 High mean o5 5.0 4.5 Control 4.0 Control mean 3.5 3.0 Low mean Selection for low fat 杜洛克背膘厚度选择实验效果 2.5 2.0 246810121416 Generations ig 2.1. Duroc generation means of backfat thickness(Hetzer and Miller, 1972)杜洛克背膘厚度选择实验效果