calving date

14 cows were divided into the control and treatment groups on the basis of parity and expecting calving date.

本实验选用14头年龄、胎次、产奶量、乳成分基本一致的奶牛，分为对照组和试验组。

The correlation values between maternal additive genetic effects of growth traits and calving date were from 0.01 to 0.20.Significant influences of herd and sire on almost all growth traits were found;

母体加性遗传效应与配种-产犊天数的相关值为0.01～0.20，两者间没有什么必然的关联。公牛效应是影响生长性状的重要因素。

50 cows were divided into experiment group and control group according to milk yield, calving date and lactation.

实验选用了50头奶牛，根据产奶量、泌乳天数和胎次相近的原则分为试验组和对照组。