The adaptive capacity of farm animals determines the impact summer heat has on animal productivity. Scientists are beginning to discover ways to influence the adaptive capacity of farm animals to reduce heat stress and its negative consequences for animal welfare and farm profitability in response to rising temperatures. Free Ebook to download at the end of this article
Temperatures are on the rise with climate change
As June approaches temperatures are rising and so is the risk for heat stress in farm animals. Temperatures are rising, not just because we are at the end of May, but also in general. Our climate is changing, and we can expect to see increases in temperature over the coming century. According to recent predictions, global temperatures are expected to rise by 1.4–3.0°C by the end of this century.
Increasing concerns on production losses because of high ambient temperatures are not only relevant for the tropical areas of the world, but also for countries occupying the temperature zone in which heat stress is more of a seasonal problem during the 2 to 3 summer months. The U.S. livestock production industry incurs an estimated total annual economic loss of $1.69 to $2.36 billion due to heat stress.
Genetic selection programs carried out in optimally controlled conditions improved productivity traits in livestock, however it has also enhanced the susceptibility of animals to high ambient temperature, due to the strong relationship between production level and metabolic heat production. Global warming will further accentuate heat-stress related problems in livestock.
Adaptive capacity of farm animals
The vulnerability of livestock to heat stress varies according to species, genetic potential, life stage, management or production system and nutritional status. Among livestock species goats are thought of as the most adaptive species to climate change. They can tolerate severe heat loads, as well as extended periods without water and feed.
Animals have adaptive mechanisms to cope with rising temperatures, which involve morphological, behavioural and genetic capacity for change.
Coat colour is an important morphological trait, whereby light/white-coloured coats in animals are recognized as being advantageous in terms of adaptive ability to high temperatures. Behavioural changes seen in heat stressed animals include using shade whenever they have access to it and a reduction in feed intake.
The adaptive process can be expanded to include morphological, physiological, behavioural, metabolic, neuro-endocrine and cellular responses.
Some of the physiological parameters for adaptation to heat stress are respiration rate, rectal temperature, pulse rate, skin temperature and sweating rate.
The adaptive mechanisms help the animals to adjust to rising temperatures. However, they can compromise the productive potential in most species, in favour of maintaining regular energy supply for vital physiological functions.
Importance of identifying animals with high heat tolerance
Research into the physiological changes accompanying high temperature, in tropically adapted species, is increasing the understanding of the mechanisms that the animal uses to accomplish the necessary functions efficiently and to find ways to support a more efficient response to minimize the impact of heat stress on performance.
Identifying relevant biomarkers in animals capable of maintaining high levels of productivity during heat stress will also help to breed for climate resilient animals.
Impact of heat stress on farm animal productivity
In general animal responses vary according to the duration and the intensity of the thermal challenge
Physiological and metabolic adjustments resulting from the thermoregulatory responses to a thermal stress have negative consequences on animal productivity and health.
The reduced animal performance can to some extent be explained to be the result of both direct and indirect effects of heat stress on reducing feed intake. Another portion of the reduced performance is due to effects on reproductive physiology, health, energy metabolism and on deposition of fat and protein.
Many of the negative consequences that heat stress has on animal health and productivity are mediated by reduced intestinal barrier integrity. Heat stress also results in the production of reactive oxygen species (ROS), which if uncontrolled can lead to oxidative stress and inflammatory responses further down the line.
Apart from affecting animal productivity, rising temperatures may also put an increased strain on the physiological ability of farm animals to cope with already existing stressful stages of production, such as early lactation.
Free Ebook – Guide to adapting to summer heat for livestock
Want to know more about the adaptive capacity of livestock and how to support them during the summer months? Download our free guide to adapting to summer heat for farm animals.
A guide to adapting to summer heat for farm animals
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