There is an increasing interest in feeding dairy heifer calves higher levels of calf milk replacer (CMR) than the traditional 750-900g CMR/day. Accelerated feeding programmes refer to milk intakes of more than 8 litres or more than 1.2kg CMR/day and there are many benefits of this documented in research.

Traditionally, the idea behind restricting milk volumes was to encourage starter feed intake for good rumen development to allow early weaning. However, it is now known that growth performance is restricted on this kind of system.

Research suggests that feeding higher levels of milk early on in life leads to higher liveweight gains with heavier calves at weaning. In addition, there has been shown to be superior organ growth and development (of the rumen, small intestine and mammary gland), providing longer-term benefits to animal performance, notably more milk being produced in the first lactation.

Data from two US dairy herds showed that average liveweight gain before weaning was very closely correlated to milk yield in the first lactation and for every 1kg increase in average liveweight gain pre-weaning, heifers produced 850kg and 1113kg more milk in the first lactation in the two herds respectively.

Weaning will however require careful management to ensure that calves on high levels of milk are consuming sufficient starter feed for good rumen development and overall dry matter intake once milk is removed from the diet. Generally, the higher the level of milk feeding, the longer the step-down weaning period should be. Studies have indicated that around 45 days is the ideal time to start weaning calves off milk to increase starter feed intake when targeting a 56-day weaning age.

Where calves are left to suckle their dam or are fed ad-libitum milk, they can consume up to 20% of their body weight a day and achieve weight gains of more than 1kg/day – considerably more than the 0.8kg/day target that has been suggested for Holstein Friesian calves and for them to have doubled their birthweight at weaning at eight weeks of age.

For a 50kg calf, 20% intake equates to 10kg of milk and through natural suckling a calf will drink 7-10 times a day, considerably more feeds than what would typically be provided in a bucket system or with automatic calf feeders.

At SRUC’s Crichton Royal Farm in Dumfries, changes were made earlier this year to the calf rearing enterprise, with positive impacts on growth rates and health. Previously, calves went straight onto CMR after one 4-litre feed of colostrum and were housed in individual pens for the first week of life, after which they were moved to group housing and fed through an automatic feeder, up to 7litres of milk at 15% CMR inclusion (1.05kg CMR/calf/day).

Now, after their first feed of colostrum, calves are fed transition milk from newly calved cows and receive up to 7.5litres until 14 days of age (in individual pens), after which they move onto an automatic calf feeder with CMR. Here, calves are stepped up from 7.5 litres to 9.5 litres of milk (with 13.5% CMR inclusion so 1.28kg/calf/day) and then start the weaning process at 67 days of age, being completely weaned by 84 days – significantly later than the previous system where calves were weaned at 56 days. The CMR was also changed from a whey-based (24% protein, 20% oil) to a skim-based product (22.5% protein, 25% oil).

The target is now to wean calves at a minimum weight of 110kg and some have been as heavy as 130kg, with an average daily liveweight gain of 0.95-1kg/day from birth to 84 days. On the previous system, average daily liveweight gain was 0.3kg less, at 0.65-0.7kg/day. Other observations include less health problems with lower treatment rates for scours and pneumonia.