Cattle farmers are being urged to take steps to prevent calf growth rates falling when winter bites and temperatures drop.
According to Frank Wright Trouw Nutrition International Technical Manager John Twigge, calves are extremely susceptible to cold weather and growth rates will suffer as soon as temperatures drop.
“Calves have a relatively high ratio of surface area to bodyweight which means they will chill very quickly,” Mr Twigge explains. “The thermo-neutral temperature for a calf is 20°C and as soon as the ambient temperature falls below this energy is diverted to keeping their core body temperature at 38.9°C. Even at temperatures of around 15°C, calves have to increase ‘energy burn’ to maintain body temperature. Once energy is diverted to keeping warm other functions start to suffer including growth rate and the immune system, making calves more susceptible to disease challenges.”
Mr Twigge stresses that in colder weather it is essential to increase the nutrients fed, and this means increasing the concentration, not the volume of milk replacer fed. He explains that the higher nutrient supply will preserve growth rates and help maintain body temperature.
While in normal climate conditions calves being fed for standard growth rates may typically be fed 500g of milk powder per day, usually made up as a four litre replacer at a concentration of 125g/l, he advises increasing the concentration of milk replacer to 150g/l (600g powder per day). In prolonged or very cold spells as seen in recent winters he advises that feed rates of 180g/l (720g powder per day) have been beneficial. He comments the actual feed rate might vary depending on the manufacturer, feeding method and growth targets so it is important to follow the manufacturer’s instructions.
“The extra calories fed will have a big impact on performance. If night temperatures in the calf house drop from 15°C to 0°C, growth rates will fall by 24% unless compensated for by an increase in milk powder consumption. Farmers may be reluctant to increase milk concentrations on grounds of cost but the return in terms of maintained growth rates and fitter, healthier calves can far outweigh the investment in superior calf nutrition.”
In addition to increasing feed rates, Mr Twigge advises making sure bedding is kept dry and that calves are protected from draughts as both will have the effect of chilling calves.
“It is totally predictable that calves less than four weeks old will be thermally stressed in a UK winter. You can be certain it is going to happen so it will pay to do all you can to minimise the problem. In extremely cold weather it will also be advisable to defer weaning until conditions improve,” Mr Twigge concludes.