Calving difficulty has an obvious negative impact on the profitability of a herd through increased calf, heifer and cow mortality, slower re-breeding performance and considerable additional labour and veterinary expense.

Whilst many large studies have consistently shown birth weight to be the most important genetic factor influencing calving difficulty, there are other aspects that also need to be considered, including calf shape, dam pelvic area and dam calving “will”. BREEDPLAN Calving Ease EBVs attempt to take all the factors affecting calving difficulty into consideration and allow the best possible genetic improvement to be made in ease of calving.

Interpreting Calving Ease EBVs

BREEDPLAN produces two Calving Ease EBVs; these are Calving Ease Direct & Calving Ease Daughters.

(i) Calving Ease Direct

Calving Ease Direct EBVs are estimates of genetic differences in the ability of a sires’ calves to be born unassisted from two year old heifers. The Calving Ease Direct EBVs are reported as differences in the percentage of unassisted calvings.

Higher, more positive, Calving Ease Direct EBVs are more favourable. For example, a bull with a Calving Ease Direct EBV of +5.0% would be expected, on average, to produce 3% fewer difficult calvings from two year old heifers than a bull with a Calving Ease Direct EBV of –1.0% (6% difference between the sires, then halved as they only contribute half the genetics).

(ii) Calving Ease Daughters

Calving Ease Daughters EBVs are estimates of genetic differences in the ability of a sire’s two year old daughters to calve without assistance. The Calving Ease Daughters EBVs are also reported as differences in the percentage of unassisted calvings.

Higher, more positive, Calving Ease Daughters EBVs are more favourable. For example, a bull with a Calving Ease Daughters EBV of +4.0% would be expected to on average produce two year old daughters that have 3% less calving problems than the daughters of a bull with a Calving Ease Daughters EBV of –2.0%.

While Calving Ease Direct EBVs are of importance for all beef producers, the Calving Ease Daughters EBV should also be considered in self-replacing herds.

For more information regarding Calving Ease EBVs, please contact staff at your BREEDPLAN processing centre.