16 June 2021 - Heat stress is an issue that is problematic from both an economical and animal welfare perspective. Climate change is expanding the scale of the heat stress challenge and livestock producers are having to put in place new strategies to address this challenge.
While it is an issue that can be impacted by many different approaches based on the animal’s surroundings, animal nutrition providers are learning more about how research-led feed formulation can reduce the impact of heat stress. Phileo by Lesaffre is one company that has invested in learning more about this challenge and how different dietary solutions can tackle this problem. We spoke to Alain Riggi, Global Species Manager for Poultry, Ruth Raspoet, Poultry R&D Manager and Elen Rondel, Western Europe Poultry Manager, to understand the role animal nutrition can play in heat stress, the field of postbiotics and how their product Safmannan can address this issue.
[Feedinfo] Can you explain why is it so important for poultry producers to focus on addressing heat stress?
[Alain Riggi] The climate is changing and global warming is a real issue that everybody is facing. Among domestic species poultry seems to be particularly sensitive to temperature-associated environmental challenges, especially heat stress. Most poultry production methods in modern farming systems involve large numbers of birds living in controlled environments that favour high ambient temperatures, especially in summer. When associated with high humidity levels, these temperatures lead to reduced performance and can result in suffering and death, which means substantial economic losses for the poultry producers.
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Approximately 50% of the commercial poultry production in the world is located in tropical areas of the planet, with projected growth showing this will continue to take place within these tropical regions (especially in Asia, Africa and Latin America). In these areas, when high environmental temperature is coupled with high humidity, the heat stress effects can be detrimental to commercial poultry operations. When the birds are heavy, for example when the broilers reach 2kg body weight at 35 days old, they suffer more from heat stress and the risk of mortality is much higher. If the mortality occurs at this stage after all the investments including feed cost have been made, the economic loss for the poultry producer can be huge. Heat stress is estimated to cause a total annual economic loss to the U.S. poultry industry of $128 to $165 million. Broilers subjected to chronic heat stress face significantly reduced feed intakes (16.4%, up to 50%), lower body weights (32.6%) and higher feed conversion ratios (25.6%) at 42 days of age, so this is a critical issue. |
Alain Riggi |
[Ruth Raspoet] As a response to heat stress, several physiological adaptations are taking place. Blood flow will be redirected from the core of the body to the periphery, leading to a decrease in blood flow in internal organs such as the gut. This can lead to the leaky gut syndrome, characterized by the translocation of bacteria and bacterial products such as lipopolysaccharides (LPS) into the internal environment. The immune system can then be stimulated with production of pro-inflammatory cytokines such as IL-6.
When the exposure to stress is acute the sympathetic-adrenal-medullary system (SAM) will be activated, leading to initiation of a defence mechanism with release of catecholamines such as adrenaline. When the stress is maintained or becomes chronic, high amounts of adrenaline can become toxic and lead to activation of the hypothalamus-pituitary-adrenal (HPA) with secretion of glucocorticoids such as cortisol and corticosterone. These glucocorticoids interfere with the immune system and the thyroid hormone metabolism that regulates body temperature and are involved in stimulation of growth and development of birds. Consequently, when heat stress is maintained for a long period, glucocorticoids can have deleterious effects on the animals zootechnical performance and immunity. High glucocorticoid levels cannot be maintained for long periods and so when chronically exposed to high temperatures, if no efficient countermeasures are taken, birds will become hyperthermic and die.
[Feedinfo] How can you effectively manage heat stress in poultry?
[Alain Riggi] An efficient heat stress management should be an integrated one. Through many years of research with different partners, universities, independent research centres, large poultry integrators, and small to middle scale poultry farms, we identified 4 main pillars of holistic heat stress management.
The first pillar is house equipment. This includes equipment adapted to hot weather like fogging systems and evaporation systems. Poultry house orientation should be chosen with the objective to allow air flow and adequate ventilation is essential. The second pillar is farm management. There are many management practices that may stress broilers and laying hens during peak hours of heat stress, such as catching, loading transporting broilers to the slaughterhouse during the hottest part of the day. The administration of vaccines in drinking water is a common practice, but during the hot season when the birds drink more it is important to calculate the water consumption to ensure proper dilution of the vaccine. The third pillar is feeding regimes. In addition to the common practices like temporary feed restrictions, we recommend our customers impose a feed restriction at an early age (4 to 6 days old) to adapt the digestive system to fasting during acute heat stress periods later in birds’ life. During the heat stress period, the use of some additives, such as the coccidiostat nicarbazine, may increase deaths dramatically so an alternative coccidiostat should be used during the heat stress season.
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Elen Rondel |
[Elen Rondel] The fourth pillar is nutritional strategies. By adding a selected postbiotic like Safmannan, we can mitigate the negative effects of heat stress in birds. When the temperature increases, this decreases energy requirements, which reduces the basal metabolism of the bird and thus decreases feed intake. However requirements for protein and vitamins remain the same, so nutritional strategies should be applied during heat stress episodes to overcome the adverse effects. Attempting to increase feed intake in this situation can be counterproductive, as extra heat would be produced by digestion. Increasing feed energy density can help reduce growth depression and this energy level can be boosted by adding more fat, as it has a lower heat increment than carbohydrates. Special care must be taken when considering the energy/protein ratio and several studies show lower protein diets give better results than higher protein diets. Intermittent feeding or fasting can also be beneficial to reduce heat production during the hottest periods. |
[Feedinfo] What are postbiotics? Can you tell us about how postbiotics work to address heat stress?
[Alain Riggi] Postbiotics are a new category in animal nutrition. On May 4th, 2021, International Scientific Association of Probiotics and Prebiotics (ISAPP) published the official definition of postbiotic as “preparation of inanimate microorganisms and/or their components that confers a health benefit on the host”. Safmannan, is a good example of a postbiotic. It is a selected yeast fraction, obtained from advanced fermentation of proprietary Saccharomyces cerevisiae strain that is rich in mannan-oligosaccharides and beta-glucans (1.3 and 1.6). We continue research on Safmannan, despite completing more than 100 trials as we keep investigating the product’s mode of action and benefits in poultry. Our aim is to provide a premium quality product which replies to our customers’ needs and we believe we do so.
A number of trials conducted under heat stress conditions, demonstrate that adding Safmannan in chicken’s diet can help decrease the body temperature of the birds and modulate hormone and corticosterone secretions. Birds fed Safmannan suffer less from the heat stress and reach much higher growth level, with excellent FCR, compared to control groups. This consistent result has been observed through different trials conducted in the world in tropical areas like India, Mexico, Brazil, and less tropical areas, like France, Spain and China. When we investigated further how Safmannan addresses the heat stress issue in birds, we found that birds in groups fed Safmannan have better immune responses, better vaccine response and cell mediated immunity (CMI), while also improving gut health. The overall effects of Safmannan on birds under heat stress result in a ROI above 6:1, up to 10:1.
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[Ruth Raspoet] Although the exact mode of action of Safmannan against heat stress is still under investigation, it could be hypothesized that Safmannan induces a better resistance against acute and chronic heat stress by an indirect action on the HPA-axis with less secretion of glucocorticoids. This means fewer negative effects on thyroid metabolism, the immune system and animal performance. This indirect action on the HPA-axis is postulated due the presence of B-glucan within Safmannan. These B-glucans might modulate the immune system leading to a reduced production of Il-6 and stimulation of the HPA-axis. Another argument supporting this theory is the positive effect of Safmannan on the intestinal barrier and the potential of Safmannan to bind a variety of pathogenic bacteria. A strengthened epithelial gut barrier and an adequate pathogen binding will reduce the translocation of the bacteria to the internal environment and thus diminish the contact of bacteria with the immune system leading to a decrease in IL-6 production and thus HPA-axis stimulation. |
Ruth Raspoet |
[Feedinfo] You mentioned over 100 trials have been conducted. Can you explain the evaluation process for Safmannan and the research you have done here?
[Ruth Raspoet] We conducted different types of trials across the world in collaboration with universities, independent research centres and our customers, including research trials (under controlled conditions), research trial under field conditions (mimic industry practices) and field trials (under field conditions). Several trials have illustrated the effects of Safmannan on the intestinal barrier. A trial in Japan with factorial design showed that Safmannan increased the mucin production in both non-heat stressed, and heat stressed birds. A similar trial also performed in Japan, showed that heat stress was inducing leaky gut syndrome with impairment of tight junctions, while administration of Safmannan under these conditions strengthened the gut and prevent the translocation of harmful substances into animal’s systemic organs.
[Elen Rondel] Trials performed in Mexico and China showed that heat stress increased the body temperature of the animals, while Safmannan was able to counterbalance this increase. Additionally, trials performed in Central Asia showed that supplementation increased the birds zootechnical performance under heat stress, while also lowering the corticosterone concentrations. Another trial performed in Mexico demonstrated that birds under heat stress had better thyroid hormone levels when they were given Safmannan. In Brazilian and Chinese trials when heat stressed broilers were fed Safmannan, this resulted in a better feed conversion and a mortality reduction. Additional trials have found Safmannan can help retain feed intake, decrease FCR, increase body weight and reduce mortality, leading to increased revenue for the farmers.
[Feedinfo] Can you talk to us about the development of your smartphone app to further support poultry producers?
[Alain Riggi] To help our customers to quickly evaluate the heat stress level in their farm, Phileo has developed a smartphone application “Program Heat stress poultry”. The first part of this apps is based on the index, THI (temperature humidity index), which evaluates the level of heat stress related to birds’ body weight, age, ambient temperature and relative humidity. The impact of heat stress on birds is not only due to the high temperature but the combination between temperature, humidity and birds’ age and body weight. After a few clicks, the poultry producers can discover the level of THI in their farms and then the app can indicate the increased level of performance that an efficient heat stress program would bring. Furthermore, we have compiled the key elements of integrated heat stress management in a technical guide which can be found on our website. We hope poultry producers can then adopt these strategies to improve meat production gain, feed efficiency (FCR), birds’ survival, economic gain and animal welfare.
Published in association with Phileo by Lesaffre
