Perhaps our biggest objective in calf rearing is to transform the calf from being a monogastric into a ruminant as efficiently and effectively as possible.

The rumen will be the ‘engine’ that delivers the energy required for the rest of cow’s life and performance. The bigger and more effective the engine, the better the lifetime performance.

How do we best measure when a calf has made the leap from monogastric (where the calf gets most of its energy via the readily available and easily digested milk) into ruminant (where the calf’s rumen is sufficiently developed to facilitate the supply of sufficient energy for the calf to continue to grow and develop well without milk)?

Travelling the world to see how different dairy farmers choose to wean their calves shows a wide range of strategies. Some wean on age – always at 70 days, others at 56 days or earlier. Others wait until their calves achieve a certain age or weight and then stop feeding milk.

We have known farmers who have been rearing calves for many years use an automatic milk machine to wean calves by day 56, reckoning that on average, their calves will have achieved 1.5kg dry matter intake by that age, and be sufficient to live without milk, supported entirely by the output of their rumen. Others use a target of 2.0kg of dry matter intake over 3 consecutive days. Traditional targets of 1kg dry matter intake from starter feed, coarse mix or blends for three consecutive days have more recently been increased to 1.5kg or 2kg as we have gained a greater understanding of how crucial this level of dry feed intake is to allow for a successful weaning.

A calf is ready for weaning when it is capable of supporting its own energy requirement via the outputs and performance of the rumen, and a useful measure of that ability is the measure of a daily dry matter intake of 15 – 2.0kg.

Some farmers who have been using Axcelera-C and experienced accelerated rumen development in their own calves will find that their calves have achieved the 1.5kg+ dry matter intake 2-3 weeks earlier than when they had used just liquid milk and starter feed. We have worked with farmers who use a milk machine to manage the weaning curve to their surprise find that accelerated calves were intaking 4kg of dry matter by day 56 (instead of the typical 1.5kg), and have changed the weaning curve to wean them 2 weeks earlier. Had they used age as the measure of when to wean, then they would have offered liquid milk much longer than necessary, with the added costs and management time involved.