Investigating dairy calf selection as an estimate of finished carcase conformation and returns from different quality pure dairy bull calves
Project number: 72603
Lead contractor: Blade Farming SW Ltd
Start & end date: October 2008 – March 2010
Actual end date: July 2010
Increasing numbers of Holstein male cattle are coming forward from the dairy herd as milk producers try to breed more heifer replacements and increase production in the light of quota increases. These calves are often available at relatively low prices compared to continental-cross calves and when cheap feeds are also available have the potential to generate a positive margin in well managed finishing units. However, the value of the final carcase is dependent on its conformation, with P grades attracting heavy price penalties compared to O grades.
The objective of this trial is to assess any differences in performance and financial returns from a range of pure dairy bull calves of apparently different carcase conformation potential (assessed as young calves) finished intensively for beef production.
32 fit and healthy Holstein or Holstein cross dairy bull calves were allocated to two groups based on their apparent conformation score. One group was estimated to achieve a conformation grade of -O or O+, whilst the other was estimated to achieve a conformation score of -P or P+ at slaughter. All calves were blood sampled at the collection centre to allow levels of circulating immunoglobulins to be measured.
All calves will be reared on the same unit with each pen containing equal numbers of calves from both groups. At approximately 14 weeks of age the reared calves will be transferred to the finishing unit, where they will be fed an intensive cereal based ration until the point of slaughter. Cattle will be selected for slaughter on the basis of their fat cover, aiming for fat classification 2 or 3.
The areas in which differences in performance were significant were:
- Start liveweight of the calves at selection/start of rearing, was 9kg lower for group P calves than group O calves, despite the ages of the calves being similar.
- Calf mortalities during the rearing phase tended to be greater in group P than group O (19 vs 0%, respectively).
- A parameter called weight for age‘ was shown to be a good indicator of a calves potential growth rate and carcase weight, showing a positive relationship in both cases. (Calculated as weight at collection centre divided by age).
- Lighter weight calves appeared to have poorer conformation but this did not result in statistically poorer conformation carcases at slaughter
- Both weight and conformation are likely to reflect early management of calf on the dairy farm – a good start to life is vital, and this is where colostrum quality and intake is so important
- Weight for age would seem to be a useful predictor of calf health and performance potential and worthy of further investigation
- The main losses of lighter weight, poorly conformed calves tended to be during the rearing phase
- Veterinary treatment during the rearing phase can enable cattle to achieve good performance in the finishing phase
- Growth rate during the finishing phase was similar for both groups