Climate change risks to livestock and fish summary
- Extreme heat causes livestock heat stress above critical temperature thresholds
- Feed intake falls 3 to 5 percent above 30 degrees
- Milk and egg yields and quality decline under heat stress
- Few fish tolerate waters above 28 degrees causing deaths migration
- Industry adaptations include shade, feeding changes, relocation and heatwave preparedness
The threat to crops from climate change has been well documented. Yields of crops such as cocoa, coffee and corn have long been impacted by high temperatures and volatile weather patterns.
But extreme heat also poses a risk to animal agriculture around the world, both on land and in the sea. This not only poses a risk to the species themselves, but can impact the quality of outputs: eggs and dairy coming from heat-stressed livestock are often of lower quality.
For any manufacturer with animal products in their supply chain, heat poses a profound risk, reducing productivity and depleting quality. This has the potential to impact margins.
The risk to livestock
The risk to livestock from extreme heat is significant, according to a joint report by the UN’s Food and Agriculture Organisation (FAO) and the World Meteorological Organization (WMO).
The range of air temperatures at which livestock can control their core body temperatures without losing energy or experiencing heat stress is 25 °C for goat and sheep, and 24 °C for chickens and pigs, who cannot sweat. Dairy cows are also particularly vulnerable due to their large size.
Above these thresholds, animals begin to come under increasing levels of heat stress. While at lower temperatures, the additional energy expended is minimal, in extreme cases, this can lead to organ failure, cardiovascular shock and death.
Wind speed and humidity can affect an animal’s response to heat stress.
Even in lower temperatures, livestock are affected negatively. Higher temperatures can affect the efficiency by which animals convert feed into energy, for example. If animals are biological machines and the feed is the fuel, extreme heat makes the fuel less efficient.
Furthermore, for each degree above 30 °C, goats, pigs, sheep, chickens and cattle reduce feed intake by 3-5%.
This has knock-on effects. With less energy consumed and more energy expended, the animals in question will reduce their productivity. This can mean fewer eggs for chickens, and less milk from dairy cows.
The quality of these yields can be reduced as well. Milk from heat-stressed animals has lower fat and protein content. Eggs from heat-stressed chickens have thinner shells and altered yolk quality.
Heat stress can also delay the onset of puberty in animals, and reduce rates of conception.
Studies show an overall risk of declining productivity among livestock as a result of rising temperatures.
The impact of heat stress on humans may also negatively influence agriculture, points out Hideki Kanamaru, climate change officer for FAO.
“All of these agriculture productions are ultimately managed by humans. They need to work outside, many of them, and they will be exposed to greater heat stress.”
The risk to fish
Fish are not immune from the impacts of extreme heat, despite not being on the land.
Extreme heat can affect water quality: warm water can hold less oxygen, which can impact reproduction, immune system response and even lead to death for fish.
As with livestock, heat stress can affect digestion and assimilation of nutrients for fish, affecting both growth and reproduction.
Heat stress can also lead to harmful algal blooms. Often, when these blooms die, their decomposition can deplete oxygen, leading to areas with low or no oxygen and causing widespread fish death.
While threshold temperatures vary between species, very few fish thrive in water temperatures above 28 °C.
Fish in shallower water bodies are more vulnerable, points out FAO’s Kanamaru, as the water can heat up more quickly.
On top of the adverse impacts on the health of fish, higher temperatures have also been found to be causing fish to migrate towards the Earth’s poles and into greater water depths, to escape warming water temperatures.
What can industry do?
While climate change is still with us – while temperatures are still increasing – agriculture and fisheries must do what they can to adapt.
For manufacturers relying on animal products in their supply chains, pushing for such adaptation is vital to mitigate the impact that extreme heat has on productivity. This can, of course, impact profit margins.
What might this adaptation look like? Some methods are simple and relatively cheap; adding shade for livestock, for instance, or changing feeding patterns so that animals are not digesting food during the hottest part of the day.
Others are more complex. In the long-term, the industry can move to new locations, or even change livestock species to those who are more heat-tolerant.
The industry should also aim to prepare for heatwaves, implementing the necessary infrastructure to help livestock deal with the incoming weather and minimise heat stress, such as small-scale water infrastructure for example.
“Heat can be predicted in advance,” stresses Kanamaru. “There are many things that can be done to manage heat risks on the ground”.
Climate change remains a significant threat to crops. But livestock and fish are far from exempt, and food and agriculture must ensure it remains vigilant for such risks.
