Significant problems also arise when only a selection of animals in a contemporary group are performance recorded. For example, only the performance for the best animals in the contemporary group is submitted to BREEDPLAN. In this situation, the performance information for an animal will only be compared with the “selection” that has been recorded. If this “selection” is not an accurate reflection of the entire contemporary group, then BREEDPLAN can not make adequate comparisons and the EBVs produced may be biased or misleading.
The table below provides an illustration of the problems caused by selective recording.
| Animal | 200 Day Weight (1) | 200 Day Weight (2) |
| A1 A2 A3 A4 A5 A6 A7 A8 A9 A10 |
255 238 261 205 187 265 237 195 258 228 |
255 238 261 X X 265 237 X 258 X |
| Average | 233kg | 252kg |
The problem caused by selective recording is demonstrated if we consider animal A7. In the first scenario, all 10 calves in the contemporary group have been recorded and A7 is 4 kg heavier than the average of the group (237 kg vs 233 kg). This is an accurate reflection of how this animal ranks compared to his peers.
However, in the second scenario, the weights for the lightest 4 calves have not been recorded. A7 is now 15 kg lighter than the “average” of the group (237 kg vs 252 kg). The selective recording of this group has resulted in the performance of A7 being compared against a misleading average. As BREEDPLAN can only calculate EBVs based on the information that has been recorded, the subsequent EBVs that are calculated from this performance will also be misleading (i.e. biased).
What should be done is:
- Adopt a whole herd recording strategy
- Record all calves with your breed society
- Always record performance for all calves in a contemporary group and submit this performance to BREEDPLAN
- Record performance on all available animals (i.e. heifers, bulls & steers, rather than just bulls).