Nutrition and milk feeding periods in dairy calves are a golden opportunity to maximise your growth rate, get it right and you will prime your growing heifers for a productive milking future when they enter the adult herd at a target of between 23 and 26 months of age.

That’s the advice from Volac business manager for Scotland, Alan Smith. He maintains a heifer calf’s relative ability to turn nutrients into growth peaks during the early life milk feeding period, so you simply have to take maximum advantage.

“During the first two months of its life, a dairy heifer calf is able to turn 100g of feed into 50g of growth. That’s a feed conversion efficiency of 2:1 or 50%, but as the animal ages this diminishes steadily; so much so that by the time a calf is 15 months of age, 100g of feed will be delivering just 8g of growth,” he said.

Feed efficiency is at its optimum during the milk feeding period because liquid milk is more nutritious and digestible than concentrate feed – adding that prior to puberty, heifer growth focuses mainly on bone and muscle, whereas later in life heifers gain more fat and are therefore less feed efficient.

By not taking advantage of the high feed conversion efficiency early in life heifers will have to grow more later in life (when feed conversion efficiency is low) to reach the same body weight at first calving.

Environmental stress can adversely affect feed conversion efficiency.

“During periods of cold weather and/or disease challenges, calves will use more energy from their feed to keep warm and fight disease, leaving less energy available for growth.

“Feeding the right amount of a well-mixed, proven calf milk formula is crucial when making the most of the early life feed conversion efficiency. Both ingredients and volume of milk fed can affect feed efficiency; the more digestible your milk replacer, the more efficient it will be at delivering growth,” he added.

A milk replacer’s digestibility is influenced by the type of protein and fat source used, along with its manufacturing process. Consequently, it always pays to buy a calf milk replacer from a trusted supplier.

“Provided your colostrum management and feeding protocol is sound – and your calves have access to fresh water, roughage and a palatable starter concentrate – we know that feeding a good heifer calf up to 900g (750g minimum) of calf milk replacer daily will allow you to meet optimum rearing targets. The peak milk allowance (6-8 litres per day in maximum 3L feeds) should be reached by two weeks of age. Indeed, these feeding levels are absolutely crucial if you want to calve heifers down with an adequate body size at 24 months,” he points out, however, calves fed more milk will not be driven by hunger to eat starter feed to support weaning. Meaning high milk fed dairy calves need to be encouraged to eat solid feed by implementing management strategies that balance the intake of nutrients from both milk and starter feed.

During the first two months of its life, a dairy heifer calf is able to turn 100g of feed into 50g of growth, but as the animal ages this diminishes steadily

During the first two months of its life, a dairy heifer calf is able to turn 100g of feed into 50g of growth, but as the animal ages this diminishes steadily

Calf starter should be introduced from days three to five, but calves don’t typically begin consuming measurable amounts of solid feed until they are around two weeks of age.

“By five weeks of age calves should be eating 0.5kg of starter feed per day. Calves should be eating 0.7-1kg per day by six to seven weeks of age and a minimum of 1.5kg per day at weaning,” he said, that offering forage alongside starter feed is also important for healthy rumen development.

“Feeding forage helps stabilise the rumen pH, stimulates its muscular layer and maintains the integrity and health of its wall. What’s more, providing chopped barley straw – separately from starter feed during the high milk feeding period – has been shown to stimulate starter intake, improve calf weight gain and even boost forage intake after weaning,” he added.

Finally, Mr Smith stresses the importance of setting target growth rates and then monitoring calf and heifer body weight at regular intervals to make sure your rearing programme remains on track.