AGRICULTURE – Heat, it’s not just humans who suffer from it. For many farm animals, such as rabbits, the situation is likely to be much worse. While about eight out of ten animals are grouped together in buildings, enclosures or pools without access to the outside, the heat wave that is looming is likely to be deadly.
For most farm animals, “the preferable temperatures range from 17°C to 24°C”, underlined in June 2021 a study by German and American researchers published inThe Lancet. Beyond that, it leads to heat stress, causing a decrease in milk production for cows, eggs for hens… And of course, mortality rates skyrocket.
In 2019, the heat wave episode that hit France between the end of June and the beginning of July caused many losses. The association for the protection of farm animals Welfarm had thus identified an excess mortality of around 40% in pig and poultry production sites. The stakes are therefore high since the number and intensity of these heat episodes is bound to increase due to climate change.
What is heat stress?
In addition to temperature, there is also humidity. Indeed, the 2021 study states that “stress temperature thresholds are lower when humidity is higher”. Concretelythe more humidity there is in the air, the lower the temperatures need to be to be dangerous for livestock.
Temperatures even become deadly if they climb above “35°C with high humidity or above 40°C with low humidity”, explains the study published in The Lancet. However, this is what is happening in a good part of France.
If the “thermal stress” becomes unbearable and therefore lethal for the animals, waves of deaths decimate the farms. This has been observed for several years now in Africa, with the terrible droughts affecting Somalia in particular. In recent days, heat and humidity have washed away nearly 2,000 cattle in Kansas, the nation’s third-largest producing state.
In France, farms had to deal with two intense heat waves in 2003 and 2019. Nearly 20 years ago, the heat caused a hecatomb in poultry farms in the West of France. More than 1.7 million animals had perished in this way. All species combined, no less than 6 million poultry died during this heat wave. And during the summer, “significant increases in collections of bovine corpses, which could reach 50%, have […] been observed by rendering companies in the western departments”, underlined the senators in a report on the heat wave.
That of 2019 was also particularly hot and deadly, as evidenced by the increased activity during this period of rendering services. The latter had a lot of work since “from June to August, the collection increased by 23% in meat poultry”, indicates for the magazine To succeed Yannick Carré, member of the interprofessional organization Anvol, which represents some poultry farmers.
Limiting the damage, without solving the problem
In addition, not all breeders are prepared to deal with high heat. This is the case in the west and north of France, which previously did not have to regularly face temperatures exceeding 30 degrees. Conversely, farmers in the southern half of the country are more accustomed to dealing with summer heat.
Their production system has been adapted, with a reduced density of animals or even a temperature acclimatization system. When the latter rise, fans engage with a system of cool padding (the equivalent of a bottle of frozen water in front of his fan). Some breeders have also invested in misters, as seen in the tweet below:
But that doesn’t solve everything. First of all, many farms maintain a high animal density and do not offer access to the outside for the animals, aggravating the heat within the buildings. A bit like being in the pit of a packed concert hall.
There is also the question of the energy and carbon footprint of the use by some breeders of air conditioners. In addition, various solutions (foggers, watering the roof to cool the structure, etc.) require water, which risks becoming scarce with the drought. On this question, the hydroclimatologist Florence Habets explains to the HuffPost that “to preserve water in quantity and quality, it is recommended that agricultural plots be surrounded by hedges, or even in agroforestry”.
The contribution of plants seems indeed essential because, through evapotranspiration, they serve as very effective natural air conditioners while reducing the risk of drought. Nevertheless, it is difficult to have plants and trees in intensive livestock buildings. Another argument weakening the maintenance of this agricultural model.
See also on the HuffPost: Faced with the heat wave, tips for cooling down without warming the planet