Having got this far, the goal with calf growth during this period is to feed the young heifer so that it meets correct growth and weight targets. What should your calves be eating right now?
This is the period in the dairy calf’s life that is characterised by a shift from starter ration to concentrate mix and free choice hay. The ration fed to young heifers should be energy and protein-rich. Mineral supplementation should also be provided for the standard five (calcium, phosphor, magnesium, sodium and potassium) as required, but these can usually be found in concentrates.
To maintain an average daily weight gain of around 0.8kg/1.5lb per day, the calves should be fed a diet that combines 16-18% crude protein, 35% acid detergent fibre, and 11MJ ME/kg DM.
At five months calves should weigh about 150kg. The calf should be offered forage but around two-thirds of dry matter intake should come from concentrate, and this should be carefully monitored – an imbalance in the proportions can cause digestive problems and hinder proper development.
The forage quality should also be carefully selected for calves at this age. Fine-stemmed, mould-free hay or hay silage are preferred; high-quality corn silage will also do nicely.
This is about the period when the calf may also be introduced to grazing, where this is available. Pasture is often the cheapest feed source and is therefore likely to make up the bulk of the young heifer’s feed. But the rumen does not reach mature proportions until around 6 months and unless pasture quality is high (at least 10MJ/kg DM of energy) feed intake and animal performance may be restricted by rumen capacity.
Farmers often rely on average quality pasture to rear heifers, with quality pasture being reserved for milkers. That policy should be reversed, offering the heifers quality grazing to ensure that they consume sufficient energy and protein.
A pasture-only diet may still not provide sufficient nutrients, and the young heifer may need to be fed either a mixture of up to 2 kg/head/day of cereal grain, or conserved fodder to complement the diet. The quality of the conserved fodder should still be high enough to provide 9-10 MJ/kg DM of energy.
Last, but not least: water. Clean water, and plenty of it, should always be available on demand.