Inheritance of Fertility in Cattle Inseminated Artificially

Abstract

Higher conception rates were obtained in both virgin heifers and cows when the following estrus characteristics were present at insemination: good standing heat, presence of heat mucus, intense red color of the internal portion of the vagina, easy cervical passage with a pipette, good uterine contractions, normal ovaries and follicles, and soft follicles. Precise determination of these estrus characteristics was difficult, and heritability estimates ranged from 0 to 0.24. Consequently, an improvement in fertility by selection of these characteristics would be uncertain. Heritability and repeatability estimates of nonreturn rates after first insemination in virgin heifers in herds with low fertility were 0.17 and 0.23, respectively, and nearly zero in herds with good fertility. Thus, the use of nonreturns to first insemination for virgin heifers in herds with low fertility appears to be more valuable for fertility improvement through selection, because 1) these data can be obtained very easily and 2) this measurement determines the fertility complex better than other traits evaluated. © 1969, American Dairy Science Association. All rights reserved.