中国肉用西门塔尔牛育种目标性状的选择及其经济权重的测算

为了选育中国西门塔尔牛肉用品系，本研究从中国肉用西门塔尔牛育种实践出发，确定了适应当前中国肉用西门塔尔牛的育种目标性状和选择性状。采用差额法计算出各目标性状的边际效益，并通过各目标性状表型值的遗传标准差校正边际效益，得到相应育种目标性状的经济权重。结果表明，中国肉用西门塔尔牛近期的育种目标性状主要包括生长发育性状（断奶重、育肥期日增重、18月龄体重）、胴体性状（胴体品质、屠宰率、净肉率）及繁殖性状（初产年龄、产犊间隔和留群时间）。在现有市场和生产条件下，上述育种目标性状的边际效益分别为17.93元/kg、16.2元/kg、7.17元/kg、297.99元/级、497.82元/%、594.46元/%、-3.62元/d、-26.55元/d、232.75元/y，3类性状中生长发育性状、胴体性状及繁殖性状的经济权重之比为31.49%：15.86%：52.65%，约为2：1：3，繁殖性状占总经济权重最高，其次是生长发育性状和胴体性状。综上所述，在中国肉用西门塔尔牛育种过程中，繁殖性状具有最重要的地位，需加强繁殖性状的选择力度。

Selection of Objective Traits and Estimation of Economic Weights for Chinese Simmental Beef Cattle

In order to breed a beef line in Chinese Simmental cattle,this research defined breeding objective traits and selected traits according to real breeding condition of Chinese Simmental beef cattle.Using the balance method to calculate the marginal benefit of each objective trait and getting the corresponding economic weight of breeding objective traits through the standard value of the error corrected marginal benefit of breeding objective traits.The results showed that breeding objective traits mainly included growth traits (including weaning weight,fattening daily gain,18th month weight),carcass traits (including carcass quality,dressing percentage,pure meat percentage) as well as reproductive traits (including age at first calving,calving interval,stay group time).In the current market and production conditions,the marginal benefit of the breeding objective traits were 17.93 yuan/kg,16.2 yuan/kg,7.17 yuan/kg,297.99 yuan/grade,497.82 yuan/%,594.46 yuan/%,-3.62 yuan/d,-26.55 yuan/d and 232.75 yuan/y,respectively,and the ratio of relative economic weights of three kinds of traits was 31.49%:15.86%:52.65%,similar to 2:1:3,and reproductive traits occupied larger economic weight,was better than growth traits and carcass traits.The results indicated that reproductive traits played an important role in the process of breeding in Chinese Simmental beef cattle,and we needed to strengthen the selection of reproductive traits.