THERE ARE myriad options when it comes to feeding calves, and a whole raft of factors that will likely influence your decision.
While whole milk is easily available on farm, it may be more economical to use a good quality calf milk replacer when milk prices are high or when milk pathogen load puts calves at risk of transferrable disease.
Milk should always be fresh and clean, and collection/storage/feeding equipment needs to be maintained to the highest of standards.
Feeding milk from sick or mastitic cows increases the risk of transferring pathogens or antibiotic residues to calves and may increase the risk of antimicrobial resistance in your herd.
CMRs usually supply somewhere between 22 to 25 per cent protein and 18 to 22 per cent fat (both on a dry matter basis).
Most CMRs are based on skim-milk powders.
Protein may come from sources such as wheat and soy, however milk-based proteins are much easier to digest for newborns.
When it comes to CMRs, consistency is key. Any sudden change in product or mixing rate could be harmful to your calves if you do not allow their digestive systems time to adapt.
If using a CMR, it is likely your product selection will depend somewhat on your calf-rearing system; but always read the label, mix according to manufacturer’s directions, and prevent scavenger access.
Fortifying milk (adding a CMR to fresh milk) can produce a liquid feed higher in nutritional value and has the potential to improve heifer growth and health outcomes.
In south-west Victoria, a study comparing calves fed 4 litres whole milk with those fed four litres fortified (whole milk + 150 g of a 25prot:20fat CMR) found the calves fed fortified milk gained significantly more height and weight by eight weeks of age.
There are numerous factors to consider before switching to a fortified feeding system; it would not be advisable to do so without further investigation.
With temperature, consistency is again the most important factor.
Warmed (38°C) and chilled milk can both have good results, but don’t swap between the two.
In colder climates, cool milk has the potential to lower a calf’s body temperature such that they will need to divert extra energy away from growth and development towards returning to a normal body temperature.
If following low volume feeding recommendations of 10 to 12 per cent body weight per day (4 litres/day of whole milk or a 20:20 commercial milk replacer in a 40 kg calf), you can expect average daily gain of approximately 0.25 to 0.4 kg in a comfortable thermal environment.
However, if environmental temperatures are excessively hot or cold, these same calves can actually experience weight loss at this rate of feeding as they burn energy to maintain their thermoneutrality.
Calves will begin to consume concentrates and fibre to increase their energy intake, although their digestive ability and therefore intake is limited in the first few weeks of life.
High-volume approaches (increased volume per feed, feeds per day, concentration or fortification) has the potential to increase calf satiety, weaning weights, lifetime milk production and fertility, and reduce disease incidence pre-weaning.
Higher volumes can however come with higher associated costs, and increased need for individual monitoring — good hygiene is essential.
Although the jury’s still out on exactly how frequently calves should be fed for optimal growth and development, traditional calf rearing operations in Australia usually work around twice daily feeding systems.
This allows for close observation and early detection of signs of disease.
Calves can be successfully reared on either teats or buckets; although teat feeding helps calves satisfy their natural desire to suck, thus reducing the incidence of cross sucking and cross-sucking associated diseases.
Automated feeding systems mimic the natural feeding patterns of the calf on a cow, providing set amounts of milk at intervals chosen by the calf.
Auto feeders have the potential to reduce nutritional or non-infectious scours if properly managed, but just as easily can become a source of rapid disease transmission amongst a group of calves.
The best way to determine whether your current approach to calf feeding is optimal for your operation is to monitor both height and weight of around 10 per cent of the group (recording weight alone may give misleading information on growth as it may not be a true reflection of skeletal growth and muscle/fat deposits).
A recent study from south-west Victoria found that for every additional 0.1 kg body weight gained per day during the pre-weaning period, an increase of 345 litres, 6.1 kg of fat and 7.5 kg of protein resulted at 250 days into their first lactation.
As always, engaging in the services and advice of your local veterinary and nutritional advisory team is recommended if you are looking to make any changes or wish to discuss your calf rearing system in more detail.
For more information, you can attend a Rearing Healthy Calves workshop in your region or download a copy of Dairy Australia’s manual
- Dr Lucy Collins
Lucy Collins works as an on-farm veterinarian in Kyabram with Apiam Animal Health, and alongside her partner on his 600 cow dairy farm in Dixie.
Dr Collins is completing her dairy residency with The University of Melbourne.