Heritability estimates of pregnancy rate in beef cows under natural mating.

摘要: Observations of 3,029 matings over 17 yr on an Ozark upland range were used to estimate heritability pregnancy rate in Angus, Hereford and Polled cows. Pregnancy rate, the percentage cows exposed that produced a live calf spring, was transformed using empirical logit transformation then analyzed for each breed separately by weighted least squares mixed model procedure. A numerator relationship matrix sires incorporated into sire account relationships among sires. Variation years significantly affected all three breeds. Age dam Angus groups. Paternal half-sib estimates from observed binary data (h2b) calculated first-calf heifers mature breed. Respective h2b .17 .09 group, .04 .01 group .05 group. The when records probit scale (h2) +/- .003 .02 .001 .002 0 cows, respectively. Heritability this study are agreement with literature, indicating little opportunity improvement selection within