Livestock farmers are being urged to act now to protect cattle and sheep from the hidden effects of heat stress, as another heatwave is forecast to hit the UK this week.
While soaring temperatures are often associated with reduced feed intake and lower performance, experts warn the greatest threat may come from damage to gut health, weakened immunity and increased oxidative stress, all of which can affect growth rates, fertility and immune function.
The issue can be further compounded at this time of year, when grazing livestock may already be receiving lower levels of trace elements such as cobalt due to seasonal declines in pasture. Combined with reduced feed intake during hot weather, this can leave animals increasingly vulnerable to deficiencies.
Maintaining trace element intake is a key part of helping livestock remain resilient during periods of extreme heat, explained Nettex’s technical manager Nia Williams.
“One of the biggest challenges during hot weather is that livestock naturally reduce their feed intake. That means they are consuming fewer trace elements and vitamins at a time when their bodies actually need greater nutritional support to cope with the physiological effects of heat stress.
“When cattle and sheep become overheated, blood flow is redirected away from the digestive tract towards the skin to help dissipate heat. This reduces the supply of oxygen and energy to the cells lining the gut and weakens the tight junctions which hold these cells together. When this happens, bacteria and toxins can enter the blood stream, a condition known as leaky gut.
“This can trigger widespread inflammation as the immune system responds to invading toxins. As a result, energy is diverted away from growth, milk production and reproduction, while animals may also experience reduced feed efficiency, digestive upset and poorer nutrient absorption.”
Heat stress also increases the production of free radicals in the body, placing animals under greater oxidative stress. Without sufficient antioxidant defences, cells become more vulnerable to damage, affecting overall health, performance and recovery.
Research shows that optimising trace mineral nutrition can help livestock better cope with these challenges. Zinc supports intestinal integrity by maintaining the tight junctions of the gut wall, while selenium, alongside vitamin E, plays a vital role in the body’s antioxidant defence system, helping to reduce oxidative stress.
Mrs Williams added: “Supporting animals with highly bioavailable trace elements during periods of heat stress helps maintain gut function, supports immune health and strengthens natural antioxidant defences. Combined with good management practices, it can significantly improve resilience during challenging weather conditions.”
She said farmers operating more extensive grazing systems may wish to consider longer-acting supplementation strategies, such as Endurabol Cattle or Sheep boluses. For weaned lambs, Nettex Cobalt, Selenium and B12 Drench can help support trace element status as pasture cobalt levels begin to decline through the summer.
“Now is a critical time. Heat stress doesn’t just affect animals in the short term, it can have lasting consequences. For example, high temperatures can affect fertility. In rams, sperm production takes around two months, while in ewes, follicle development takes around six months. As a result, the impact may not become apparent until the autumn breeding season.
“Alongside providing shade, plenty of fresh water and reducing handling during the hottest parts of the day, farmers should also review their nutritional programme to ensure livestock continue to receive adequate trace elements and vitamins, even when feed intake declines,” added Mrs Williams.
