The critical role of dEB and gut health during heat stress

Common physiological disruptions caused by heat stress

Oxidative Stress and Cellular Damage

One of the primary physiological responses to heat stress is oxidative stress. Excessive production of reactive oxygen species (ROS) overwhelms the bird’s natural antioxidant defense mechanisms, leading to cellular damage. This oxidative imbalance negatively affects proteins, lipids, and DNA, impairing growth, immune function, and overall health. Birds experiencing oxidative stress often exhibit lower feed efficiency and increased susceptibility to infections, contributing to economic losses in poultry production.

Acid-Base Imbalance and Respiratory Alkalosis

Unlike most mammals, birds lack sweat glands and rely on panting to dissipate heat. Panting increases respiration rate and promotes evaporative cooling but also results in excessive CO₂ loss. This leads to respiratory alkalosis, which disrupts the acid-base balance in the blood, forcing the body to compensate through metabolic adjustments. The resulting metabolic acidosis can further impair health and productivity by altering nutrient metabolism, enzyme activity, and electrolyte balance.

Neuroendocrine Disruptions

Heat stress affects the neuroendocrine system by increasing plasma corticosterone levels while decreasing thyroid hormones, which are critical for energy metabolism. Elevated corticosterone concentrations suppress immune function, making birds more vulnerable to disease, while reduced thyroid activity lowers metabolic efficiency of the animal, further leading to production losses.

Gut Health and Intestinal Integrity

The gastrointestinal tract is particularly vulnerable to heat stress. Oxidative stress and acid-base imbalances compromise intestinal integrity, leading to increased permeability, commonly known as "leaky gut". This condition allows pathogens and toxins to enter the bloodstream, triggering systemic inflammation and increasing the risk of infections. Tight junction proteins, such as occludin and zonula occludens (ZO), play a crucial role in maintaining gut barrier integrity. Heat stress disrupts these proteins, leading to chronic injuries, villi sloughing, and epithelial cell shedding, which reduce nutrient absorption and digestive efficiency. Furthermore, heat stress impairs the mucosal immune system by reducing intraepithelial lymphocytes and IgA-secreting cells, weakening the bird’s ability to defend against enteric pathogens.

Behavioral and Productive Changes

Birds under heat stress exhibit behavioral adaptations aimed at reducing heat load, including increased water consumption, reduced activity, and panting. While these behaviors help regulate body temperature, they also contribute to decreased feed intake, leading to weight loss and poor feed conversion ratios. In broilers, heat stress leads to higher fat deposition, lower protein content, and poorer meat quality. In laying hens, it reduces egg production, egg weight, and shell quality. The cumulative effects of heat stress significantly impact productivity and profitability in poultry farming.
Heat stress poses a severe challenge in poultry production, affecting physiological functions, gut health, immune response, and overall performance. Understanding these impacts is essential for developing effective mitigation strategies to protect bird health and maintain optimal production.

Important during heath stress is to be able to maintain gut health and ensure that the gastrointestinal tract can exerts its role properly. The combination of valeric and butyric acid esters is a recent innovation that has shown great results in this field.

Combining Valeric and Butyric Acid Esters for Gut Health

Valeric and butyric acid esters are short-chain fatty acids that offer significant benefits to the gut health of broilers, particularly under heat stress conditions. Butyric acid, especially in the form of glycerol esters, has been extensively studied and is known for its positive effects on gut morphology. It increases villus height without impacting crypt depth, thereby improving the villus height to crypt depth ratio, a key parameter for assessing gut health in birds. This improvement in gut morphology enhances nutrient absorption and overall gut function. In addition to its effects on gut morphology, butyric acid esters promote increased microbial diversity and modulation of gut microbiota. They enhance the immune response and improve gut integrity by facilitating the assembly of tight junctions, which are crucial for maintaining the intestinal barrier. This supporting of the intestinal barrier helps prevent the translocation of pathogens and toxins from the gut into the bloodstream, reducing the risk of systemic infections and inflammation.

While there are fewer studies on the effects of valeric acid esters in chickens, the available research indicates that valeric acid plays an important role in reducing intestinal inflammation and maintaining gut integrity. Valeric acid has been shown to increase the presence of goblet cells in the small intestine of mice, which are responsible for mucus production and protection of the gut lining. 

Both butyric and valeric acid esters help mitigate the negative effects of heat stress on the gut, contributing to better overall performance in broilers. By promoting a healthy gut environment, these compounds play a vital role in maintaining broiler health and productivity. The synergistic combination of these ingredients is due to their wide spectrum mode of action. Simply explained, butyrins act as an energy source for colonocytes, supporting intestinal cell differentiation and nutrient absorption. On the other hand, valerins contribute antimicrobial and anti-inflammatory properties, promoting better usage of energy in the gut and overall gut health.

Studies conducted by Perstorp Animal Nutrition in cooperation with various facilities worldwide and reported in literature have described general beneficial effects of the combination of both acids in the form of a commercially available product, Gastrivix™ Avi. This product has been shown to result in better gut health, significant improvements in growth performance, FCR, and reduced mortality during at older ages.

In summary, valeric and butyric acid esters are effective tools for supporting the gut health of broilers, particularly under heat stress conditions. Their ability to enhance gut morphology, microbial diversity, immune response, and gut integrity makes them valuable additions to poultry diets. By promoting a healthy gut environment, these compounds help maintain health and productivity in broilers, making them resilient to the challenges posed by heat stress.

Sodium Formate for Dietary Electrolyte Balance

Optimizing the dietary electrolyte balance (dEB) is crucial for broiler performance, especially under heat stressed conditions. Formulating diets to maintain electrolyte homeostasis is essential for broiler health and performance. Optimization of the dEB is critical for various physiological functions such as nutrient absorption, bone density, heart and breathing rate, and overall metabolic processes. Sodium formate can be used as an alternative source of sodium to ensure optimal dEB levels in the diets, with the additional benefit of having antimicrobial properties. Sodium formate provides formic acid, which is known to have a bacteriostatic effect on pathogenic bacteria, especially Gram-negative bacteria such as Salmonella and E. coli.

This can further reduce the passage of harmful bacteria into the small intestine, thereby supporting gut health and reducing the risk of infections. The formate ion helps to keep in-feed pathogens to a minimum, ensuring that the gut environment remains healthy and conducive to nutrient absorption. In addition to this, sodium formate as an alternative source of sodium compared to other sodium sources - like sodium bicarbonate for example - helps to better formulate diets to minimize the increase in acid-binding capacity (ABC) of the feed, which is crucial to ensure proper performance. By using sodium formate, it is possible to maintain lower ABC value while still providing the necessary sodium for electrolyte balance.

Heat stress can severely impact broiler performance, but sodium formate in the form of feed-grade additives like ProPhorce™ AC 299 helps mitigate these effects through its multi-action on dEB, pathogen control, and maintaining a lower ABC value. By maintaining electrolyte balance, you can help to prevent issues such as respiratory alkalosis, which can be lethal under heat stress conditions. Additionally, the antimicrobial properties of sodium formate help maintain a healthy gut microbiota, reducing the risk of infections that can exacerbate the negative effects of heat stress. Studies have shown that optimizing the dEB with sodium formate can lead to significant performance gains. Adjusting the dEB can improve weight gain and feed conversion ratio (FCR). 

ProPhorce™ AC 299 impact on broiler mortality after a heat stress challenge. (Perstorp trial, Imasde (ES), 2013)

In summary, ProPhorce™ AC 299 is a valuable tool for supporting poultry health under heat stress conditions. By optimizing dietary electrolyte balance and controlling pathogenic bacteria, it helps maintain electrolyte homeostasis, support gut health, and improve overall performance. The dual benefits of sodium formate are an effective and efficient solution for managing the challenges posed by heat stress in poultry.

Conclusion

Managing heat stress, maintaining gut health, and optimizing dietary electrolyte balance are essential for improving broiler performance. The use of compounds such as valeric and butyric acid esters, and sodium formate can help achieve these goals, offering significant benefits for poultry farming. By addressing these critical factors, poultry farmers can enhance broiler health, productivity, and overall well-being.

ProPhorce™ AC 299 is a sodium formate-based solution that supports poultry health under heat stress conditions. It effectively manages dietary electrolyte balance (dEB) and helps to control pathogenic bacteria.

Gastrivix™ Avi contains glycerides of butyric and valeric acid. Together, these compounds help to maintain gastrointestinal health resulting in better feed conversion ratios (FCR), body weight gain, and overall performance.

Incorporating such products into poultry diets helps manage heat stress, maintain gut health, and optimize dEB, enhancing poultry gut health and productivity.

References available upon request.