We do the following initial selection procedures (please refer to the 2 articles selection procedures with our 14 month old heifers before we put them to the bull:
- Adaptability and functional efficiency are first priorities
- Selection for frame size that best meets our environment
- Pelvic measurements which were done at 12 months are taken into account and we do the following :
- Group 1: All animals with anatomical defects of the pelvic bones are culled.
- Group 2: Animals in the lowest 20% of pelvic index scores are not mated at 14 months but only at 24 months.
These animals are sold off and we do not use them in the Hartebeestloop stud.
- Animals that are in the lowest 20% and where there is a history of difficult calving in the mother line are moved to Group 1 and culled.
- Group 3: These are the heifers that are just above the lowest 20% pelvic index group They present with pelvic index scores that are 95 and lower. Traditionally we have mated these heifers with specialist calving ease bulls. Our selection criteria are much stricter now (from the lowest 15% in the past to the current lowest 20% that are not mated at 14 months) and the management of this group is also better than in the past. We would still use calving ease bulls for this group but have moved away from the specialist calving ease bulls as identified in the past to open young heifers.
- Group 4: These heifers present with pelvic index scores between 95 and 105. We mate them very successfully over a number of years now with all rounder bulls with moderate growth rate BLUP values.
- Group 5: They are the top group and presents with pelvic index scores of 105 and more. We have tried our luck using bulls that should be used on cows only – broader framed bulls with high growth rates and well defined muscling. The idea was that the heifer’s pelvic index scores are so high that they would calve without problems from these bulls. It was a bad idea and an even worse plan! This group should be managed no different from Group 4 and all rounder bulls with moderate growth rates should be used.
We had tremendous success in reducing calving difficulty (distokia) and heifer casualties since pelvic measurements were introduced.
It is important to note that we only select for pelvic area once the selection for medium-framed animals are done.