While steps are often taken to reduce heat stress in milking dairy cows, it is important not to forget the impact of heat on calves.
Acalf’s thermoneutral zone is between 10-25degC and, while they tend to cope better with heat than adult cattle, they will become heat stressed if the temperature rises above this level.
This can increase the risk of dehydration, reduce feed intake and cause stress, lowering immunity. All of this can impact on average daily weight gain, risk of disease and even mortality. Longer term, this can also affect breeding size and age at first calving.
High humidity and poor airflow can increase the chance of pneumonia and, in heavily stocked buildings, can cause heat stress in cooler months as well as in summer.
Kirsty Ranson, of Westmorland Vets, says: “One of the real challenges is managing calves if the weather is fluctuating between extremes with cold nights and very warm days, particularly if you are using calf jackets, so it is important to monitor calves and their environment closely.
“In hot weather, it is critical calves take on enough fluid so they do not become dehydrated.
“They have a very strong sense of smell and taste, so it is vital to ensure water is not tainted and is clean, fresh and palatable at all times. Make sure you have a good fly control practice in place, as not only do they spread disease, if calves are bothered by flies, it will suppress their appetite.
“In summer, it may be possible to move calves to better ventilated buildings which have been vacated by older cattle providing they have been thoroughly cleaned, disinfected and left to dry beforehand. This will give the chance to thoroughly clean and disinfect calf housing and leave it empty for a while, which will help reduce disease challenge for future months.”