How much milk should dairy replacements get?

Feeding dairy heifers more than six litres a day can prevent them from eating enough starter concentrate.

Speaking at a recent AHDB event at Halton Farms, near Congleton in Cheshire, Alex Bach, research professor at the Catalan Institution for Research and Advanced Studies (ICREA), questioned why calf rearers were feeding more milk.

He cautioned: “If you are offering lots of milk, the animal will pull back on starter. The right balance for me is three litres in the morning and three litres in the afternoon.”

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He added that this should be mixed at a rate of 150g/litre, requiring 900g of powder in total.

He said he often saw a check in growth at weaning because calves were not eating enough starter and their rumen had not been properly prepared for the transition from milk.

Man inside a cattle shed

Dr Alex Bach © Rhian Price

Which feeds to choose

He advised farmers to feed high-quality milk replacers containing 25% protein and 25% fat to avoid “overwhelming” calves with too much lactose.

“One with 18% fat and 22% protein will have too much lactose and you can end up overwhelming the stomach,” he said.

He added that concentrate must be of high quality and palatable, and farmers should look for products that are 40-45% starch and above 20% protein, containing no more than 5% molasses.

Straw is the best forage to provide adequate fibre for rumen development, but it must be chopped to 2.5cm and included in small amounts – ideally, only 5% inclusion when mixed with concentrate, he added.

“Straw is ideal. If you don’t have straw, use poorer-quality hay high in fibre and lower in protein. It is the physicality rather than nutritional quality that matters.”

He stressed that forages must be free from mycotoxins and palatable.

Dr Bach said silage should be limited until heifers are 180 days of age and the rumen is able to digest it.

He said the target was to achieve 1kg daily liveweight gain before weaning and for this to increase to 1.2-1.3kg daily after weaning.

“If you feed less milk, calves will eat more concentrate, and you want them consuming at least 2.5kg/day [of concentrate] before weaning,” he added.