Farmers are being urged to increase milk replacer feed rate as cold weather continues to grip the country.

With temperatures running at below 5C, young calves need more energy to maintain body temperature, which will be at the expense of growth unless quantities of milk replacer are increased, warns Provimi ruminant product manager Philip Ingram.

As a quick guide, Dr Ingram suggests that for every 5C drop in temperature, when ambient temperature falls below 15C, an extra 100g of milk powder a day is required.

Traditionally, calf milk replacers tend to be fed on a restricted basis containing between 18% and 20% fat and 22% to 24% crude protein, contributing about 2.5mJ of metabolise energy for every litre of milk fed. A milk replacer of this specification and fed at 500g a day will only support growth rates of around 400g per head per day depending on environmental conditions.

“More recent trial work has shown us that these feeding rates are not exploiting the young calf’s potential and they will almost certainly under perform in colder temperatures,” adds Dr Ingram.

Calves should be able to consume more than 750g of milk powder within the first weeks of life to support growth rates of at least 600g. Feeding more milk replacer with a higher crude protein content will improve body weight gain and also lean gain at the expense of fat.

Trial work carried out by Provimi shows that to maintain a growth rate of 600g a day, three-week-old Holstein calves require about 17mJ of metabolise energy at temperatures of 19C. This would increase to 19mJ a day if environmental temperatures drop to below 10C.

“It is also important to offer calves solid feed from the first or second week of life to try and fill this energy gap,” adds Dr Ingram. “However, the quantity of dry feed intake is generally still low in the second week of life in winter conditions and is typically less than 100g a day. It is therefore important that the energy requirements are met at this time of year through increased high quality milk replacer.”

• For more news, information and advice on youngstock management see our Youngstock: Stop the Loss pages