British summers are getting warmer, and cattle feel rising temperatures long before we do. A mild, breezy afternoon that feels pleasant to us can already have a cow working hard to stay cool, because she is carrying the heat of digestion and milk production on top of the weather.
The good news is that beating heat stress in cattle comes down largely to sound, practical management, and the single most powerful tool on any farm is a reliable supply of clean drinking water. Get the water right and you protect welfare, milk yield and body condition through the hottest weeks of the year. This guide looks at how heat stress occurs, the signs to watch for, and how the right drinkers keep intake up all summer.
Cows are constant heat producers. Digesting feed and producing milk generate a steady flow of body heat, and on sunny days they also absorb solar radiation from above. In comfortable conditions, within what is known as the thermoneutral zone, a cow sheds that heat through breathing, limited sweating and evaporative heat loss. Heat stress occurs when the heat she gains outpaces the heat she can lose. Because cattle carry this internal heat load, they begin to struggle far sooner than people do. Dairy cows can start to feel heat stress at around 19°C, particularly once humidity is high, well before a summer day feels uncomfortable to us.
It is rarely temperature alone that tips cattle into trouble. Heat stress is driven by a combination of factors working together: temperature, relative humidity, solar radiation and air movement. The temperature humidity index, or THI, brings air temperature and relative humidity into a single figure, and in the UK’s temperate climate dairy cows face an increased risk of heat stress once the THI climbs past about 68. Beyond that point milk production starts to slide, falling by roughly 20% as the index rises from 68 in spring towards 78 in high summer. Air movement is the factor you can most easily influence indoors. Still, humid air in a shed with poor ventilation traps more heat around the animals, while good airflow helps cows cool. A well-designed roof ridge and roof lights, supported by fans where needed, all help increase airflow exactly where it matters. AHDBAHDB
Heat stressed animals show a fairly consistent set of signs, and learning to read them early makes management far easier. The clearest is breathing rate: as a cow works to lose heat, her respiration rates climb and she may pant with her head extended. Body temperature rises, she stands more and lies less, and she crowds into shaded areas and around water. Appetite is an early casualty.
Heat-stressed cows can cut their dry matter intake by anywhere from 10 to 30%, and that reduced feed intake feeds straight through to a drop in milk yield. AHDB offers a practical scoring approach based on behaviour and breath frequency, though many farmers spot the problem first as less milk in the tank. Catching these signs of heat stress promptly lets you act before welfare and production suffer.
Heat stress in dairy is more pronounced than in many other classes of stock, because milk production itself is a major source of heat. A higher yielding cow simply runs hotter. Even a cow giving around 18 litres a day generates about 28% more body heat than a dry cow, so your best performers are often the first to suffer. That does not mean the dry cow can be ignored.
Heat exposure during the dry period affects the developing calf, the immune system and the milk yield of the lactation to come, so the entire herd needs protecting, not just the milkers. Across dairy cattle as a whole the pattern holds: more heat in, less milk out, unless management keeps pace.
If one step does the most to reduce heat stress, it is keeping clean drinking water in front of cattle at all times. Water requirements for milking cows already sit around 120 to 140 litres per day, and intake rises by a further 10 to 20% in hot weather. Even lower yielding cows can drink in excess of 100 litres a day when temperatures rise. Cows also take a large share of their daily water in one go, so flow and access matter as much as total volume.
Provide enough drinking space, since around 10cm of trough space lets roughly 10% of the herd drink at once, and keep water sources close to shade and feed so animals are not forced into the hottest part of the day to reach them. Fresh water kept out of direct sunlight stays cooler and more palatable, which encourages cows to drink and supports evaporative cooling. This is exactly where automatic, self-filling drinkers earn their place: they refill the moment the level drops, so the supply keeps pace with demand and nobody is hauling buckets.
Water does the heavy lifting, but a handful of supporting steps make a real difference. Shade is the most basic and effective, so provide shade wherever cattle gather. Ample shade from buildings, trees or shade cloth cuts the solar radiation load, and stock will naturally seek out shaded areas through the hottest part of the day. Indoors, addressing poor ventilation pays off fast, lifting air movement so cows stay cool.
Where housing allows, water-based cooling that uses large droplets to soak the coat, followed by good airflow, draws heat away as it evaporates. Mind your timing too: handle and move cattle in the cooler parts of the day, early morning rather than late afternoon, and keep stock moving through any collecting yard so they are not packed together where airflow is poor. Watching body condition across the season tells you whether your heat control is keeping up, whether cattle are housed or out at grazing.
At Fisher Drinkers we have spent over 100 years helping the livestock farming community keep water in front of their animals, and our range is built for the demand summer brings. For higher capacity, the A105 holds up to 14 litres and works on higher water pressures, which is why dairy farmers and equine centres reach for it when larger livestock are drinking hard. Where competition at the water point is a worry, the A108 is a double bowl that lets more than one animal drink at the same time, easing the crowding you often see in warm weather.
For a heavy duty option, the A75 Super pairs a galvanised steel bowl with a stainless steel float cover, a lockable brass drain plug and a strong, durable valve assembly, running off a header tank or a regulated supply under 4 bar. Every bowl is self-filling, topping up automatically as cattle drink, so fresh water is always there. The galvanised steel finish stands up to years of hard farm use, and because the bowls are easy to clean, keeping water hygienic through the summer is simple. Should a drinker ever fail mid heatwave, we hold high stock of drinkers, mounting brackets and spares for fast delivery, so you are never left short.
Summer rewards the farms that plan ahead. Sorting reliable, clean water before the first hot spell is far easier than reacting once cows are already heat stressed. If you would like help choosing the right drinker for your herd, whether that is extra capacity for high yielders or a double bowl to ease pressure at the trough, get in touch with Fisher Drinkers. With over 100 years behind us, a same day response to enquiries and fast delivery across the UK, we will help you keep your cattle cool, hydrated and productive right through the season.
