ISSUE FOCUS FEED & ADDITIVE MAGAZINE June 2024 27 Heat and humidity Leaky + inflammed gut Decreased performance + efficiency Increased mortality Low profit Less feed intake Nutrient deficiency Microbiota disturbance Altered blood flow Oxygen deficiency Oxidative stress This results in electrolyte imbalances with effects on 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 a higher demand for heat shock proteins to protect from protein misfolding. • More intensive skin perfusion reduces the blood flow to the gastrointestinal tract, limiting nutrient and oxygen supply. This increases oxidative stress and has a negative impact on connections between intestinal cells (enterocytes), so-called tight junctions. • Reduced feed intake and changes in digesta characteristics can result in a dysbacteriosis. This disturbs the barrier function of the gut and fosters the risk of developing a leaky gut syndrome. In regions where heat stress is expected for several weeks or months, the strategic use of feed additives is an important measure. Three additive groups help mitigate the physiological reactions to heat stress and its consequences: 3. PROTECT YOUR ANIMALS WITH FEED ADDITIVES 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 for 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. Overall, betaine anhydrous provides extra energy (savings of ion-pumps) and amino acids (re-methylation of methionine). It ends up as a precursor of glycine and the methyl groups can be used to metabolize other temporary limiting amino acids. For example, heat shock proteins (e.g., HSP 70) play an important role in the protection and repair of protein structures and tissue. L-glutamine can support expression of HSP 70 and different trials showed a strong positive correlation between antioxidant status and the level of HSP 70 during heat stress. ORGANIC TRACE MINERALS AGAINST OXIDATIVE STRESS Reduced feed intake and changes in digesta osmolarity endangers the optimal supply of trace minerals. Absorption is reduced, and feeding high-quality organic trace minerals helps to overcome this limitFigure 1. Effect of heat stress on growth performance of poultry (adapted from Alagawany et al., 2017).
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