With autumn calving underway our minds now turn to calves and milk replacer.
Why do we feed calves the way we do?
The traditional recommendation for feeding dairy calves is to offer them 8 to 10% of body weight in whole milk or milk replacer per day. Since calves are usually not weighed at birth and the average weight of a newborn Holstein calf is about 40kg, this is generally further simplified into the feeding of 2 litres of liquid feed twice daily. This amount of liquid feed basically covers the maintenance requirements for a calf of average weight until they start to eat concentrates.
Under perfect conditions (little or no stress or disease, low infectious pressure and housing that is neither too cold nor too hot) a 40kg calf could gain about 200g weight per day with that volume of milk (4L/day). Under this regime, calves will be hungry and will start to eat concentrates early, allowing them to be weaned from liquid feed as soon as possible.
What are the limitations of this system?
There are several reasons why feeding 2 litres twice daily is no longer considered adequate:
- not all calves are average weight. If all calves are fed the same amount of milk, then heavier calves will not get enough to even maintain their weight
- there are many situations in which calves need more energy, e.g. temperatures below 15°C, heat stress, disease, or after vaccination. Under these circumstances calves may be severely underfed
- it has been shown in studies that calves that get more than 4L/day of milk grow faster, and are healthier
- heifers that grow faster before weaning calve earlier and have higher milk producing potential.
Newborn calves are totally dependent on milk as a source of nutrition.
The abomasum (the fourth stomach) is the only stomach working at this stage. For the milk to enter the abomasum, the oesophageal groove has to close by reflex, so that milk does not spill into the rumen. This works best if calves suckle from a teat or nipple.
It works also in many, but not all, calves that are trained to drink from a bucket. If the reflex doesn't work, the calves will get sick and will not thrive.
How much liquid feed should calves be offered?
Calves that are suckling the dam or are on ad-lib feeding regimes can drink about 20% of their body weight (for a 40 kg calf this is 8L/day) and will gain about 1kg per day. These calves are effectively fed ‘little and often’ by getting numerous feeds through the day.
However, these high volumes may neither be practical (unless computerised feeders are used) nor economical on many dairy farms. There is no single system of calf rearing suitable for all dairy farms and many systems can be successful. However, there are basic nutritional requirements that should be met regardless of the feeding regime.
To ensure that calves grow well and are not marginally malnourished, they should get a daily amount of at least 13 to 15% of their birth weight in whole milk or high quality milk replacer, mixed at 125 g/L water.
This should enable calves to gain about 500 - 600g per day throughout the first three weeks of life from milk alone. After this they can keep growing at or above this rate or more with the help of additional starter concentrates.
Should I feed calves once or twice a day with milk (or milk replacer)?
The abomasum of a newborn calf is not large enough to deal with the suggested volume of milk (13-15% of body weight; up to 6L/calf/day) if it is given in one feed. Calves should be fed with liquid feed twice a day until they are at least 3 weeks of age.
What is good quality milk replacer?
With milk replacer you generally get what you pay for. While there are many possible reasons for poor weight gains in young calves, the quality of the milk replacer should be included in any investigation. Milk replacer powder should be easily dissolved, leaving no sediment at the bottom of the feeders. It should be a cream colour and have a pleasant odour.
A milk replacer which contains only milk-derived proteins is preferable, especially for young calves. You should always check the label of the bag to see what ingredients and product specifications are given.
The content of crude protein in many traditional milk replacers is around 20% (on a dry matter basis). If these milk replacers are fed at the recommended feeding levels, there will not be enough protein for muscle growth. To promote muscle growth, milk replacers should have a high crude protein content (preferably at least 25% on a dry matter basis). Milk replacer should always be mixed according to the manufacturer's guidelines.
Which is better: nipple or bucket?
Feeding calves from a nipple is more natural. Drinking from the nipple takes longer and helps the calves satisfy their urge to suckle. It is preferable from a behavioural point of view. Most calves can be fed successfully from a bucket, once trained. The feeding method does not have a major impact on weight gain.
FEEDING RATES FOR DIFFERENT BREEDS
Holstein, Friesian, HF X Norwegian Red Cross:
Average Birth Weight 37-40kg:
Volume Fed L/Day up to day 5: Minimum 5 litres
Volume Fed L/Day after day 5: Minimum 6 litres
HF X Jersey cross:
Average Birth Weight 32kg:
Volume Fed L/Day up to day 5: Minimum 4.5 litres
Volume Fed L/Day after day 5: Minimum 5 litres
Average Birth Weight 28kg:
Volume Fed L/Day up to day 5: Minimum 4 litres
Volume Fed L/Day after day 5: Minimum 4.5 litres