Maximising growth rates of dairy heifer calves during the milk feeding phase is important to get calves off to a good start in life. While they tend to be fed on a restricted regime, feeding higher levels of milk has been shown to benefit weaning weights, with lower disease incidence and longer-term, more milk produced in their first lactation.
Dairy heifer calves are typically fed in the region of 750-900g of calf milk replacer (CMR) per day. However, some farmers are now looking at feeding rates of more than 1.2kg CMR/day and 8 litres plus, as opposed to the more typical 6-7 litres of milk/day.
Naturally, calves can drink up to 20% of their body weight when left to suckler their dam (or when offered milk ad-lib) and achieve growth rates of over 1kg/day, much higher than the suggested 0.8kg/day target suggested for Holstein-Friesian calves. For a 50kg calf, 20% of bodyweight means a daily intake of 10kg of milk, which is significantly more than is typically fed in a bucket rearing system or through automatic calf feeders.
While these more restricted levels of milk feeding are beneficial to encourage starter feed intake which is important for rumen development and post-weaning feed intake, the growth potential of calves is not maximised on this system.
It is well documented that feeding elevated levels of milk in early life results in higher liveweight gains with heavier calves at weaning. These calves also show superior organ growth and development (of the rumen, small intestine and mammary gland), with more milk produced in their first lactation. For example, research from numerous US studies showed that for every 1kg increase in average liveweight gain pre-weaning, heifers produced up to 1000kg more milk in the first lactation.
For farmers looking to increase milk feeding rates, weaning will need to be carefully managed so that sufficient starter feed intake is consumed for good rumen development and feed intake post-weaning, once milk is no longer fed. A longer step-down period of milk may be required, i.e. a more gradual weaning period, and the higher the level of milk being fed, the longer the weaning period should be.
Over the last 5 months, calf management at SRUC’s Crichton Royal Farm in Dumfries has changed dramatically, with calves now weaned at 12 weeks of age and being fed up to 9.5 litres of milk. This is in comparison to the previous system of weaning at 8 weeks and a maximum rate of 7 litres of milk. Other changes are:
- Following one 4-litre of feed of colostrum, calves previously went straight onto CMR. They were housed in individual pens for 7 days before moving into group igloo housing and fed through an automatic feeder, up to 7 litres of milk at 15% CMR inclusion (1.05kg CMR/calf/day).
- Now, following their one feed of colostrum, calves are fed cow’s transition milk up to 7.5 litres for the first 14 days in individual pens. On day 15 they are moved to group housing where the level of milk fed is increased up to 9.5 litres (with 13.5% CMR inclusion so 1.28kg CMR/calf/day).
- Weaning age has moved from 8 weeks to 12 weeks of age, with the weaning process starting at 67 days of age.
- The CMR has changed from a whey-based (24% protein, 20% oil) to a skim-based product (22.5% protein, 25% oil).
The target weaning weight is now a minimum of 110kg, with some calves being weaned at 130kg when 12 weeks old. As a result of these changes, growth rates have improved by 0.3kg/day, from 0.65-0.7kg/day to 0.95-1kg/day. Other benefits include lower treatment rates for scours and pneumonia.
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