Melanie Frisch, Regional Technical Manager IMEABiochem Zusatzstoffe Handels- und Produktionsgesellschaft mbH
In hot weather – especially in times of global warming – humans break out in a sweat to cool down. But how do our animals cope with the heat?
Global poultry production is facing higher ambient temperatures and extended periods of challenging climate conditions. At the same time, an efficient production is necessary to fulfill the global demand for poultry products with the lowest possible impact on climate and environment.
Unlike humans, poultry does not have sweat glands. Their physiological reactions and consequences during heat stress affect the organism differently:
- Increased heat emission from panting leads to a respiratory alkalosis through increased CO2 exhalation. The resulting electrolyte imbalances affect the intestinal osmoregulation and water consumption.
- An impaired protein and DNA/RNA synthesis can be observed on a cellular level. The animals must manage oxidative stress and have a higher demand for antioxidants.
- More intensive skin perfusion reduces the blood flow to the gastrointestinal tract, limiting nutrient and oxygen supply. This may lead to oxidative stress, tissue damage, hypoxia, and an impaired removal of toxic metabolites.
- Reduced feed intake and changes in digesta characteristics can result in a dysbacteriosis.
These reactions disturb the barrier function of the gut and foster the risk of developing a leaky gut syndrome.
Along with optimizing animal housing and ventilation, adapting feed strategies can help maintain productivity in periods of high heat stress. Feeding management, feed composition and the smart use of feed additives are three ways to adapt poultry feeding to climate change:
1. Feeding management
Shift time of feeding until after daily heat peak to reduce metabolic heat production during the hottest hours of the day
Smooth transitions in feeding during periods with chronic heat stress (longer periods with high temperature)
Avoid feed changes and make use of extra supplements via water during acute heat stress (rapid rise in temperature)
2. Nutritional requirements and diet composition
Body heat production is a result of digestion and metabolism. A certain temperature difference between the animal and the environment is needed to emit excess heat. If this is not possible, feed intake will be downregulated. Lower crude protein is an efficient measure to reduce metabolic heat production. The ratio of energy to essential amino acids should not be changed to avoid limitations in protein synthesis.
Digestible fat is the energy source with the lowest percentage of metabolic heat production. During stress, glucose becomes the predominantly required energy source. The selection of the right combination of highly digestible energy sources is crucial.
3. Protect your animals with feed additives
The strategic use of feed additives is an important measure. Four additive groups help mitigate the physiological reactions to heat stress and its consequences:
Betaine anhydrous is a multi-talent
Maintaining osmoregulation is crucial for intestinal cell functioning. Betaine anhydrous is easily absorbed and is an organic molecule with strong osmotic properties:
- It supports the enterocytes and reduces their efforts for osmoregulation via sodium-potassium-pump activity. Water retention and electrolyte supply are improved. Excessive thirst and disproportionate water intake with negative consequences for the litter quality can be avoided.
- On a metabolic level, betaine increases the supply with methyl groups that help compensate heat- induced stress (adrenaline production) as well as impaired protein and DNA/RNA synthesis. Immune functions often suppressed during heat stress are also supported by extra methyl groups from betaine.
Organic trace minerals against oxidative stress
Reduced feed intake and changes in digesta osmolarity endanger the optimal supply of trace minerals. Absorption is reduced and feeding high-quality organic trace minerals helps to overcome this limited bioavailability. Trace minerals are crucial to form antioxidative enzymes like superoxide dismutase.
Trace elements such as zinc, copper and manganese may also contribute to gut integrity. Forming central hubs in important enzymes, they play major roles in detoxifying, immunological and metabolic processes. With their improved bioavailability, organically bound trace elements allow a more efficient use of these essential micronutrients.
Pro- and prebiotics to support intestinal health
Maintaining a healthy microbiome is very important to prevent an overgrowth with pathogenic bacteria and contributes to avoid a leaky gut syndrome. The microbiome becomes disturbed by heat stress-induced changes in feed intake and feeding behavior. Pro- and prebiotics are the most used feed additives to stabilize and support a beneficial microbiome. They reduce the impact of harmful bacteria and make it possible to control the risk of toxic metabolites like LPS. Furthermore, pro- and prebiotics support feed digestibility and nutrient absorption. This is important for the animal’s resistance to heat stress and helps to minimize performance depression.
Effective mycotoxin management
Cytotoxic effects of mycotoxins can disrupt the gastro-intestinal barrier, cause oxidative stress, and strain liver metabolism. Consequently, an efficient mycotoxin management also reduces the risk for endotoxin associated diseases. This becomes especially important under heat stress conditions. The very present risk of multi-mycotoxin contamination of most raw materials in poultry feed calls for effective toxin binders with an extended binding spectrum.
In the face of climate change, heat stress is a growing problem for poultry production operations. Animals lose their ability to compensate for suboptimal feeding or management. It’s important to provide every means of support to minimize losses and help animals overcome heat stress. Feed additives play an essential role especially under continuous heat stress. These products should be used in combination with short term, on-farm application of special feed supplements during acute heat exposure.