How clean is your cow shed?
A critical way to reduce the spread of disease from one season to the next is by removing soiled bedding and thoroughly cleaning a calf shed.
One way to achieve this is by feeding fortified milk. This article gives an overview of fortified milk feeding and the things to consider before starting.
What is 'enhanced nutrition'?
Enhanced nutrition systems aim to increase calf drymatter intake from milk or milk replacer by providing a higher daily volume split over more feeds or by feeding a milk feed that has a higher overall total solids component.
What are the potential benefits of pre-weaning enhanced nutrition?
Pre-weaning nutrition and thus pre-weaning average daily gain (ADG) has lasting effects on subsequent lactation and reproductive performance.
Many studies have investigated the positive effect of increased energy and protein intake during the pre-weaning period on days to puberty, days to conception, calving live weight and first lactation milk production.
It is estimated that for every additional 0.1kg/day of pre-weaning ADG there is an increase in first lactation milk yield of 155kg.
Calves fed on a higher plane of nutrition during this period are able to combat disease challenges better than calves fed on a lower plane of nutrition.
What is fortified milk?
Fortified milk is the addition of calf milk replacer to whole milk.
This provides a high energy, high protein feed in a smaller volume than would otherwise be required to achieve a similar nutritional content if using whole milk or calf milk replacer alone.
High protein and energy allows optimal growth rates to be achieved without the need to feed high volumes of milk.
Feeding fortified milk can help overcome the challenges associated with high volume feeding programs which rely on feeding 20-25% body weight in milk volume daily.
Whole milk is about 12.7% dry matter which is made up of protein, fat, lactose and minerals.
In comparison, fortified milk can be fed at 14-19% dry matter, containing more energy and protein than an equivalent volume of whole milk alone.
Considerations before feeding fortified milk
Unfortunately there is no 'one size fits all' protocol for feeding fortified milk to dairy calves.
Every farm is different and the optimal programme will depend on the farm's current feeding system, frequency of feeding, protein:fat ratio of the milk replacer utilised, and the nature of the milk to which the milk replacer is added.
Farms with individual feeding systems, such as individual pens, locking head bails or stalls, have an advantage over group feeding systems in that an exact known volume of milk can be fed to each calf every day.
This is especially important in fortified milk feeding programmes as consumption of large volumes of fortified milk in a single feed can result in diarrhoea and/or abomasal bloat.
If only group feeding is available, there must be careful consideration of the frequency of feeding, the calf milk replacer used and the mix rate at which it is added to whole milk.
Regardless of the feeding system, ad lib fresh water must be available to all calves from birth.
Feeding of fortified milk to groups of more than 10 calves is strongly discouraged as there will be minimal control over the volumes consumed by each calf.
Frequency of feeding will also dictate the eventual mix rate of the fortified milk.
High volumes of a high total solids milk feed can increase the risk of abomasal bloat, bacterial overgrowth and diarrhoea.
The volume threshold will depend on the overall total solids of the fortified milk being fed, which will depend on the above criteria.
Many brands of milk replacer are available and unfortunately they differ in the protein: fat content, thus adding to the confusion of fortified milk even further.
One brand can rarely be substituted for another and one brand should be used consistently to avoid complications due to changes to a different replacer.
The protein and fat concentration of the milk replacer contribute to the overall total solids concentration of the fortified milk feed and differences in these will result in a difference in overall total solids for the same mix rate.
For example, 75g of a 20:20 (20% protein, 20% fat) milk replacer added to 1L of whole milk (estimated total solids of 12.7%) will result in overall total solids of 18.8%.
However, if the same mix rate is used with a 28:22 (28% protein, 22% fat) milk replacer, the overall total solids will be 19.6%.
Additives to milk replacer such as pre-biotics, pro-biotics and coccidiostats can also increase the overall total solids but their volume of contribution is unknown. The overall estimation of total solids concentration is just that – estimation. It is based on the total solids of whole milk being 12.7%.
However, if milk from the second to eighth milking after calving are used (transition milk), total solids concentration may be higher (~19%).
This will increase the overall total solids of fortified milk even further.
Whole milk from Jersey cows tends to be higher in total solids and this needs to also be considered before starting a fortified milk feed programme.
Fortified milk has been used successfully in many dairy herds.
The latest research in Australia demonstrates important increases in growth rates during the pre-weaning period compared to calves fed on conventional diets.
The potential benefits in our Australian pasture-based system are also yet to be determined and further research is required to assess whether fortified milk feeding programmes are cost-effective when all benefits and costs are considered.
It is recommended to discuss fortified milk feeding options with your health advisor before starting on a tailored program.
• Gemma Chuck is a veterinarian with The Vet Group in Victoria. Australia.
