Weaning of calves is a very important event in the development of high-quality replacements and needs to be carried out at the right time in the right way to minimise any negative effects it could have. Timing of weaning is important, as the calf is having to adapt from a mainly liquid diet to a solid diet. If the rumen has not been fully developed, the calf will struggle to get enough nutrients from the pasture and will have reduced weight gain, or even lose weight. The way weaning is carried out will also affect the performance of the calves, as stopping milk and meal suddenly will result in significant stress on the calves, resulting in reduced weight gain and increased risk of disease.
There are no specific weight targets for weaning from research, but as a rule the target weights are 70kg for a Jersey, 80kg for a crossbred and 90kg for a Friesian. Prior to weaning, calves should be eating at least 1kg of meal or 2kg of pasture as this indicates that there has been adequate development of the rumen to cope with weaning. Young calves require high protein feed going forward, so ensure that calves are weaned onto good quality pasture to maintain good growth rates.
When weaning calves, it is important that it is carried out in a gradual way to minimise stress on the animals. Slowly reducing milk allowance over 1-2 weeks will give calves time to adjust. Meal should be continued for at least two weeks after weaning and can be continued for longer if there are concerns about the quality of pasture available. There should be at least two weeks between any significant changes for calves (weaning, stopping meal, transport) to reduce the risk of any weight checks or risk of disease.
While calves are on milk they have the potential to achieve very high daily weight gains. Therefore, any late born or smaller calves are best kept on milk and meal for longer than the earlier bigger calves. Practically this can be achieved by staggering the weaning target weights i.e. the first batch of calves weaned is weaned at the lightest weights and the last batch at the heaviest weights. This gives them the best chance to catch up!
Some Anexa resources you might find helpful: