The calving season has just kicked off and with it comes the feeding of calves. Many farmers may find feeding milk replacer as a valuable activity; especially when they take into account the potential monies achievable from milk sales compared to the cost of powder.

Calf health benefits are also associated with feeding a milk replacer. However, careful attention also needs to be given to colostrum management; failing to observe the appropriate measures may inadvertently result in some calves suckling from Johne’s disease positive dams.

Irregardless of whether you feed whole milk or milk replacer, providing the calf with energy and protein is critical to support and maintain their normal bodily functions.

What to look out for

When feeding a replacer, it’s important to give serious consideration to the product that lies within the bag. The days of picking up the first bag you see in your local merchant should be well and truly over.

Remember, this is the next generation of cows you are feeding and getting them off to the best possible start will have benefits when it comes to hitting target weights and, in turn, when you’re cupping them in the parlour down the line.

According to Animal Health Ireland (AHI), the only legal requirement for declaration in calf milk replacer is that ingredients have to be listed in descending order of inclusion. And, as a result, it’s almost impossible to accurately assess the quality of a milk replacer from the label.

With this in mind, farmers can only get a rough idea of the suitability of a given milk replacer for the purpose of rearing heifers from the oil, protein, fibre and ash content.

When it comes to protein, farmers need to ensure that the protein within the milk replacer comes from dairy sources – either whey or skim powders. Failing to adhere to this and using ‘cheaper’ powders – high in plant-based proteins – will have a knock-on effect on performance.

Ideally, farmers should aim to use a milk replacer with a protein content of 23-26% when feeding dairy heifers. In addition, the crude fibre content should not surpass 0.15%; the minimum fat content should be 16-20% and ash content should sit at 7-8%.

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How soon can milk replacer be fed?

Once calves have received 8.5% of their birth bodyweight in colostrum within two hours of birth, there is no difference in their weight gain pre or post-weaning when compared to calves fed colostrum and four feeds of transition milk before moving on to milk replacer, Teagasc says.

This suggests that in well-managed systems, where the transfer of disease may be an issue, milk replacer can be offered immediately after colostrum feeding. However, the 1,2,3 rule must be strictly adhered to.

Mixing rate

Replacer is generally fed at 125g of powder to 875ml of water, which gives a solids content of 12.5% to the ‘mixed’ milk. However, this recommendation will vary between manufacturers and, given this, it’s important to adhere to the manufacturer’s instructions.

With this mixing rate in mind, a farmer feeding his/her calves 6/L per day – under a twice-a-day feeding system – needs to mix 5,250ml of water with 750g of powder.