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Calving Ease (Direct & Daughters) EBV Explained

EBVs are provided for calving ease, an important characteristic for cattle. Calving difficulty has an obvious negative impact on the profitability of a herd through increased calf and heifer mortality, slower re-breeding performance and considerable additional labour and veterinary expense. EBVs for traits related to calving ease are calculated from three main sources of information - calving difficulty score, birth weight and gestation length data.

BREEDPLAN produces two calving ease EBVs – Calving Ease Direct & Calving Ease Daughters.

Calving Ease Direct

Calving Ease (DIR) EBVs are estimates of genetic differences in the ability of a sire’s calves to be born unassisted from 2 year old heifers. The EBVs are reported as differences in the percentage of unassisted calvings.

Higher, more positive, Calving Ease (DIR) EBVs are more favourable. For example, a bull with an EBV of +5.0% would be expected, on average, to produce 3% fewer difficult calvings from 2 year old heifers than a bull with an EBV of –1.0% (6% difference between the sires, then halved as they only contribute half the genetics).

Calving Ease Daughters

Calving Ease (DTRS) EBVs are estimates of genetic differences in the ability of a sire’s daughters to calve at 2 years of age without assistance. The EBVs are also reported as differences in the percentage of unassisted calvings.

Higher, more positive, Calving Ease (DTRS) EBVs are more favourable. For example, a bull with an EBV of +4.0% would be expected to on average produce daughters that have 3% less calving problems when calving at 2 years of age than the daughters of a bull with an EBV of –2.0%.