Collecting Calving Difficulty Scores
Calving difficulty scores, in association with birth weight and gestation length information, are used to calculate Calving Ease Direct and Calving Ease Daughters EBVs within the TransTasman Angus Cattle Evaluation (TACE).
Calving difficulty should be measured at or shortly following birth by visually scoring the degree of calving difficulty on the following scale of 1 – 6.
If females are regularly checked during calving (e.g. on a daily basis), it is reasonable to assume that a calf who has been born without assistance between visits can be scored as unassisted (no difficulty) even though the calving was not observed.
- Calving difficulty scores should be recorded for the whole calf drop. Collecting “occasional” scores, or only collecting calving difficulty scores for a subset of calves is of no value and can lead to the calculation of biased Calving Ease EBVs.
- Record calving difficulty scores for all calves rather than just difficult or easy births. Recording calving difficulty scores for dead calves is particularly important.
- There needs to be some level of calving difficulty in the herd for the scores to be used effectively in the TACE analysis. That is, simply scoring all births in a herd with a calving difficulty score of [1] will not identify any genetic differences in ease of calving.
- A birth management group should be recorded if there are different treatments of the females prior to calving that may affect calving difficulty. For example, where one group of cows have had different feed availability, or where the level of calving difficulty has been affected by special circumstances (e.g. premature calves, the dam was sick etc.)
- A calving difficulty score of [2] should be allocated where calves are born unassisted but some degree of calving difficulty is evident. For example, stillborn calves where the head is swollen and it is obvious the calf has died as a result of a difficult calving.
- When calculating the Calving Ease EBVs, calving difficulty scores of [3] and [4] are grouped together. Calving difficulty scores [5] & [6] are excluded from the TACE analysis as the problems are considered non-genetic in origin.
- In addition to calving difficulty scores, birth weight and gestation length information is also included in the calculation of Calving Ease EBVs. Breeders wishing to optimise the accuracy of their Calving Ease EBVs should also consider collecting this information and submitting it to the TransTasman Angus Cattle Evaluation.
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