The recent hot weather is a reminder that temperatures above 30°C are becoming more common. Heat stress – once considered mainly a problem in tropical climates – is now an increasing challenge for cattle and sheep in Dorset.
High-yielding dairy cows, heavily pregnant animals and sheep with thick fleeces are particularly vulnerable. When temperatures rise above 25°C – especially when humidity is high and there is little wind – livestock struggle to regulate their body temperature. Even a short period of heat stress can reduce feed intake, growth rates, milk yield, fertility and immunity. In dairy cows, milk production often drops 24 to 48 hours after a hot spell, as cows eat less and divert energy away from production to keep cool.
In severe cases, heat stress can be fatal.
Early signs include faster breathing, standing for longer, seeking shade, reduced grazing, drooling and reluctance to move. As heat stress worsens, animals may pant, breathe with their mouths open, become weak and eventually collapse.
Reducing the risk
Often, some simple management changes can make a big difference:
Ensure water troughs can cope with increased demand, and provide enough trough space to reduce competition.
Provide shade wherever possible. Temporary shade structures can be effective anywhere natural shelter is limited.
Avoid handling, moving or grouping animals during the hottest part of the day.
Graze or feed during cooler periods, with a greater proportion of feed offered overnight where practical.
For housed cattle, maximise ventilation and maintain adequate space between animals to improve airflow.
Planning ahead
As hot summers become more frequent, longer-term investments may be worthwhile. Fans used alongside sprinklers or soaker systems can significantly improve cooling in housed cattle.
Also, discuss fertility management with your vet, as heat stress can affect conception rates. Breed selection may also play a role, with heat-tolerant sheep breeds and cattle genetics offering greater resilience in a warming climate.
Recognising the early signs of heat stress and acting promptly can help protect animal welfare, maintain productivity and reduce the financial impact of hot weather.
What’s happening at home
At Homefield Farm Vets we are keen to support farmers with all aspects of their business, including providing industry updates and support with team training. Please visit our website or follow us on social media for further information on our upcoming meetings and courses.
These include:
- Heat stress – how to manage it and plan ahead
- Our “Tackling TB series” – focus on wildlife control
- Sustainable parasite management – including management of gut worms, fluke and lungworm in both sheep, beef and dairy cattle and youngstock
- Lamb and kid care courses
- Calf care course (dairy focus)
- DIY AI three day course or AI refresher courses
- And we’ve much more in the pipe line!
Quick Q&A with Charlotte Fowler:
My Role: Vet. With a passion for developing youngstock rearing protocols, as well as working with block calving dairy herds.
My Favourite Farm Animal: KiwiCross cows
My Favourite Tractor: According to my toddler, any tractor will do
My Favourite Flower: Lupin
My Favourite Hobby: Anything that gets me outside, running, walking or biking.
