Thompson J R, Freeman A E, Berger P J
J Dairy Sci. 1980 Sep;63(9):1462-80. doi: 10.3168/jds.S0022-0302(80)83105-5.
Relationships of transmitting ability for dystocia with transmitting abilities for type and production in Holstein bulls were estimated. Genetic correlations between dystocia transmitting ability with Predicted Difference (PD) were: milk .00, fat .00, test -.02, and dollars .00. Genetic correlations for transmitting ability of dystocia were -.28 with Predicted Difference Type and -.23 with Type Production Index. Correlation indicated improved conformation will increase dystocia. The relationship of transmitting abilities from Mating Appraisal for Profit with dystocia indicated that scale (size) has a major effect on the type-dystocia relationship. Large size results in both high type classification and increased dystocia. Correlations of rump and center support with dystocia were also in excess of .20.
评估了荷斯坦公牛难产传递能力与类型和生产传递能力之间的关系。难产传递能力与预测差异(PD)之间的遗传相关性为:产奶量0.00、脂肪量0.00、体型评分-0.02和经济效益0.00。难产传递能力与预测差异类型的遗传相关性为-0.28,与类型生产指数的遗传相关性为-0.23。相关性表明体型改善会增加难产率。利润配种评估的传递能力与难产之间的关系表明,体型(大小)对类型-难产关系有主要影响。大体型导致高类型评分和难产率增加。臀部和中心支撑与难产的相关性也超过0.20。