关键词: 21 天妊娠率, 发情揭发率, 受胎率, 线性回归方程

Abstract: [Objective] To establish a more intuitive,rapid and convenient breeding evaluation method to provide scientific theoretical support for efficient breeding evaluation of dairy cows.[Method] Relevant reproductive data were collected and collated from 6 large-scale pastures with different breeding modes in southern and northern Xinjiang,and the correlation between 21-day pregnancy rate,estrus disclosure rate and conception rate was analyzed. A linear regression equation with estrus disclosure rate and conception rate as variables was established,and the key factors affecting the pregnancy of dairy cows were comprehensively and objectively evaluated.[Result] The 21-day pregnancy rate of adult cows was positively correlated with estrus detection rate and conception rate （P < 0.01）,and the correlation regression equation was established. For young cows, Y=-0.532+0.906X+0.599Z,R²=0.990. Adult cows：Y=-0.282+0.701X+0.415Z,R²=992 （where Y is the 21-day gestation rate,X is the conception rate,and Z is the estrus detection rate）.[Conclusion] Breeders can use the regression equation to predict the relevant indicators,quickly,accurately and conveniently improve the two key indicators of estrus detection rate and conception rate,providing an accurate basis for the monthly breeding assessment of pasture,and providing a feasible path and program for realizing efficient breeding of dairy cows in pasture.

Key words: 21-day pregnancy rate, estrus disclosure rate, conception rate, linear regression equation