The advantages of feeding milk replacer are that it can be cheaper to feed than whole milk, depending on the milk price received. It also has the benefits of being more biosecure, with a lower risk of spreading transmissible diseases, such as Johne’s disease. The other benefit of milk replacers is that they are more consistent than whole milk as the percentage of solids doesn’t fluctuate as much as whole milk can.
On the downside, milk replacers have lower energy and lower digestibility than whole milk and, depending on the feeding system used, they can require more labour than just feeding whole milk.
So, what about the price? The latest Irish Farmers Journal milk replacer price survey in Table 1 shows that milk replacers range in price from 36kg to 40kg per 20kg bag.
To understand this range better, we need to look at the quality of the milk replacer as this can have a big bearing on the price.
Unfortunately, the labels on the bag of milk replacer don’t tell us much about the quality of the product. Obviously, the percentage of protein in the milk replacer will have a major effect on animal performance.
Calves fed high-protein milk replacers have higher daily liveweight gains. But the source of the protein also has a big bearing on animal performance and the price of the milk replacer.
The best milk replacers have a high proportion of milk-derived ingredients. The protein in these products is based on whey or skim milk powder. Where the protein comes from non-milk sources, or vegetable sources such as soya, pea protein or wheat gluten, digestibility, price and subsequent calf growth will be lower. Unfortunately, it is not possible to tell if the protein is based on milk or vegetable sources by just looking at the crude protein figure on the label.
Animal Health Ireland recently issued a new information leaflet on milk replacers. It states that the percentage of crude fibre can indicate the protein source. Where crude fibre is greater than 0.15%, then the inclusion of non-milk proteins is likely.
Some manufacturing processes lead to a high mineral content in the whey protein (eg delactosed whey), which increases the risk of scours.
For this reason, milk replacers with an ash content greater than 8% should be avoided.
The oil content in the milk replacer is a milk fat substitute, but is not of major nutritional significance. The oil level should be between 16% and 20%.
On feeding levels, Emer Kennedy from Teagasc is feeding the heifer calves in Moorepark a 26% protein milk replacer from day four on. The milk replacer is made up of 15% solids, so for every one litre of milk there is 150g of milk powder.
Calves are fed five litres of milk replacer for the first week and then go up to six litres per day until weaning after 11 or 12 weeks. This is a very high feeding rate at 900g of milk powder per day.
Other than price and quality, another consideration when choosing between milk replacer and whole milk is labour availability. Depending on equipment available, it may take longer and more effort to feed calves milk replacer because the powder needs to be mixed. On the flip side, calves can be fed at a time that suits and not necessarily linked to milking times.