Genetic variation and covariation in beef cow and bull fertility.

Single-sire natural mating data from a beef cattle herd in tropical Australia were used to estimate heritabilities of cow fertility (hc2), heritabilities of bull fertility (hb2) and genetic correlations between cow and bull fertility (rg) within each of six genotypes. Estimates of hc2 and hb2 were low, averaging .11 and .08, respectively. The pooled estimate of rg was 0.16, indicating that cow and bull fertility are favorably genetically correlated and therefore that cow fertility could be genetically improved by indirect selection on bull fertility, or some more heritable component of bull fertility.