Wageningen University & Research: Five questions about heat and its impact on livestock

A hot week is coming up. With rising temperatures, we humans look for some cooling. But how does this work for animals? What can farmers do to accommodate their livestock in this heat? We asked our experts five questions about the heat and its impact on livestock.

How do you recognise animals that are suffering from the heat?
‘What happens when humans are warm? Indeed, they sweat’, poultry researcher Ingrid de Jong explains. ‘You body attempts to rid itself of excess warmth. For livestock, that is no different. It is essential to understand that pigs and chickens are unable to sweat. They need other ways of ridding themselves of the heat: often by breathing more rapidly, distancing themselves from other animals, or increasing their water intake. They also eat less because food generates heat. These are the first signs that the animals are uncomfortable.’

‘It is a little different for cows’, says veterinarian and researcher Ingrid van Dixhoorn. ‘Cows can sweat, but their first reaction will be faster breathing to relieve the warmth. Additionally, they will make adjustments to lower their heat production by eating and moving less, as well as seeking shade to cool down. Naturally, they too will drink more.’

Sometimes cows are outside in the pasture all day on a hot day. What’s that about?
‘That is, indeed, a complex issue, especially when there is little shade in the pasture. Many farmers are stimulated to leave their cattle in de pasture because this entitles them to financial compensation for pasture milk. A great initiative, but on hot days, the barn is much more comfortable’, Van Dixhoord declares. ‘Fortunately, most farmers allow their cattle to graze much more than is required for the pasture milk remuneration. So, on hot days, they allow the animals to choose whether they want to graze outside or remain indoors to cool off.’

In 2020, a format was designed for a business-specific heat protocol, specifically for the pig farming sector. How was it received?
‘I feel there were fewer issues and fewer animals perished than in 2019’, says pig researcher Anita Hoofs. ‘Pig farmers really worry on hot days and will sometimes refuse to leave their farm. The secret is that starting to think about heat when it is 25 or 30 degrees is too late. Pig farmers now start taking measures to keep their pigs cool much sooner. There is much commitment to preventing heat stress, and the heat protocol and the tips included therein help the farmers.’

The heat protocol helps farmers to draw up plans at an early stage. Thus, they can draw up an action plan with their employees and the vet to know what action is required at what temperature. That also enables you to invest in measures for the barn in a timely manner where needed. In the farrowing pen, atomisation under high pressure is popular. The investment is limited, and the installation can often be included in the existing accommodation.’

Is there low-hanging fruit? How can farmers help their animals?
‘Maximum ventilation! Create airflow using circulation fans, and if at all possible, use an atomiser. This moistens the animals, which helps them rid themselves of heat.’ This is the advice of all three researchers. ‘And, of course, ensure the animals have unlimited access to clean drinking water. You can also provide cows with easily digestible rations and buffers when hot days are expected.’

The turnaround in broiler sheds is higher than is the case for pigs or cows. De Jong: ‘There, one might consider lowering the population. Fewer animals per square metre. This solution comes at a cost ofcourse.’

And animal transport continues in the meantime?
‘To a certain degree, yes’, researcher Marien Gerritzen confirms. The NVWA (Netherlands Food and Consumer Safety Authority) ensures that animal transports are correctly done. Upwards of 27 degrees, many carriers take extra measures to reduce the discomfort for animals. Such measures include hauling in the early hours of the day or late at night, fewer animals per truck and additional ventilation during the trip. Upward of 35 degrees transporting animals is prohibited.’