There are some ‘added extras’ in caring for calves during the winter – just like getting a vehicle ready for the colder months. So says Cargill’s calf and heifer specialist Bianca Theeruth. “As temperatures fall, calves need extra energy for maintenance, so we need to feed more to avoid energy being diverted from their growth requirements.”
The temperature range – or thermoneutral zone – for calves is typically between 10°C and 25°C. Within this, the calf will generally maintain its body temperature and require no additional energy to keep warm.
Lower critical temperature
“But this temperature range varies with the age of the animal and in winter we are particularly concerned about the lower end – the lower critical temperature,” explains Ms Theeruth. “For calves that are less than three weeks old, the lower critical temperature is between 10° to 15°C. At temperatures below this, the calf will use its energy reserves to maintain a core body temperature of 38°C to 39°C, diverting it away from growth.
“For calves that are more than three weeks old, the lower critical temperature is between 5°C to 10°C, due to their more advanced rumen development, which generates heat, as well as their higher energy starter feed intake and greater internal fat stores.”
“As a rule of thumb, for every degree the temperature drops below the calf’s lower critical temperature, the energy required for maintenance increases by 1%. It is important that producers recognise this and adapt the calves’ diets so they don’t run short of energy for growth. Nutrition is first line of defence against the cold.”