Overcoming Calf Post-Weaning Lag

Equipment and calf data will suggest the weaning method best suited to your operation

Reducing heifer-raising costs is always a challenge. Over the last few years, feed and labour costs have been steadily increasing, with feed rising significantly. There's no question heifers drink a lot of milk and eat a lot of feed before they start contributing to your bottom line.

Nonetheless, dairy replacement nutrition and feeding is key to optimal health and productivity at every stage, from calves to first-calf heifers.

Proper nutritional management doesn't begin and end with newborn calves. Sound management practices should continue through weaning, feeding to meet target breeding age, pregnancy and during the close-up period before first calving.

Supporting better health and immune status through proper nutritional management can save you money in the long run. As well, feeding to meet puberty, weight and stature growth targets will help get your calves off to the right start.

Following these guidelines can help you reduce weaning stress and minimize post-weaning lag in your calves' performance.

Weaning

Weaning is an important time for your calf. Its primary nutrient source and metabolism undergo many changes at this important stage.

Recent management recommendations suggest you should increase the amount of milk or milk replacer it consumes when weaning. However, weaning your calf from these higher volumes can be challenging and often leads to declining performance or a lag phase. Your calf's digestive system must make dramatic changes to adapt to the altered nutrition source.

Your weaning method and your calf's quantity of dry matter intake has an effect on its immune system as well as overall performance like growth rate. Studies have shown no long-term effects from weaning calves between three and eight weeks of age. However, six to eight weeks is normal practice.

On the downside, calves weaned at three weeks require more stimulation to eat enough solid feed. In this case, there would be no economic benefit to early weaning if you have to spend more time feeding the calf.

Weaning age also affects your calf's immune system. Late or early weaning and the amount of milk replacer previously fed to your calf are two factors that can affect the young animal's immune system.

Timing

There are three methods for weaning calves-abruptly, gradually reducing milk volume or diluting milk. Calves can also be gradually weaned from milk when they start calf replacer. The method you choose will be limited by your equipment and calf data.

Calves weaned gradually have decreased energy intake since they don't consume enough concentrate to make up for reduced milk consumption. Abruptly weaned calves often experience weight loss and tend to crosssuckle more often.

When calves are fed by an electronic feeder, weaning success will depend on the calf's starter intake. Calves that consume starter as milk is reduced will wean earlier as opposed to calves weaned gradually at age eight to 12 weeks. These calves will also have a more developed rumen, compared to abruptly or gradually weaned calves. A calf's milk allowance prior to weaning will also affect weaning success.

In one recent study, researchers fed calves a high milk allowance of 9.21 litres per day or a low milk allowance of 4.81 L per day. For each group, half the calves were weaned abruptly at eight weeks and the other half weaned gradually during six to eight weeks of age. Both milk allowance and weaning method affected the calves' weight. Calves weaned gradually ate 50 per cent more starter. This occurred regardless of previous milk allowance.

Post-weaning weight gain was greatest for calves fed low milk allowance and weaned abruptly. This was followed by calves fed a low milk allowance and weaned gradually; then calves fed a high milk allowance and weaned gradually. The lowest weight gain was in calves fed a high milk allowance and weaned abruptly.

The results from this study show calf nutrition before weaning will determine whether weaning should occur gradually or abruptly.

Method

Factors such as labour, feed prices and equipment will help you determine the best age to wean. For instance, weaning by decreasing milk volume as starter consumption increases will help your calf's rumen mature.

On the other hand, if you're not using an electronic milk feeder, milk intake should determine weaning method. You should abruptly wean calves if their milk allowance is low and gradually if their milk allowance is high.

Reference:

Nielsen, P.P., ]ensen, M.B., Lidfors, L., 2008, Milk allowance and weaning method affect the use of a computer controlled milk feeder and the development of cross-suckling in dairy calves. Applied Animal Behaviour Science 109: 223-237.

This article first appeared in the Ruminations column of The Milk Producer Magazine, December 2010.