mechanisms show heat stress has a direct effect on the GIT, preventative efforts must include gut health.
Reducing oxidative stress When blood flow shifts to peripheral tissues during heat stress, internal organs, including the liver and intestines suffer from oxidative stress. Feeding antioxidants and osmolytes can mitigate this problem. However, antioxidant sources used to prevent heat stress effects must have a strong potential to neutralise the free radicals that cause oxidative stress. Vitamin E is used as an antioxidant in animal diets during heat stress, but has relatively little effect and works only in a lipid medium. Polyphenols are considered natural substances able to induce strong effects against free radicals generated in the GIT during heat stress. The most effective polyphenols for managing free radicals have high bioavailability and are active in both lipid and water-based tissues. Trouw Nutrition developed AOMix, a feed additive comprised of highly bio-available polyphenols with potent antioxidative properties. Supplementing AOMix during heat stress results in lower plasma MDA levels (Figure 1).
Osmotic changes Osmoregulatory interventions mitigate the breakdown of in- testinal epithelial cells and prevent the adverse effects of heat stress on villus height, thus preserving the gut’s capability for optimal nutrient uptake. As reduced performance is a key chal- lenge during heat stress, osmoregulators are recommended for supplementation before the start of hot seasons. Betaine is a trimethyl derivate of the amino acid glycine and a proven and effective osmoregulator. Trouw Nutrition’s TNIbetain effect on broiler performance was tested in heat stress conditions at the Nutreco Poultry and Rabbit Research Centre in Spain. Add- ing 1 or 2 g/kg TNIbetain significantly improved feed conver- sion ratio from 0 to 14 days of age and live weight at 40 days. The percentage of breast meat improved, especially in male broilers (+ 4.7%). Mortality was slightly lower for the highest
Figure 1 - Effect of vitamin E and Selko AOmix on plasma MDA levels in weaned piglets pre-and post- heat stress conditions.
9 Pre-heat stress 8.8
8.6 8.4 8,2 8
7.8 7.6 7.4 7.2 7
Control Vit E Selko AOmix Post-heat stress
level of TNIbetain. These results indicate TNIbetain can signifi- cantly improve broiler performance during heat stress.
Optimising gut health and function Heat stress harms gut health and functionality. Research has shown increased immune cell infiltration into the gut wall of heat stress-exposed animals. This is likely due to loss of gut barrier integrity and the translocation of pathogens, bacterial compounds and small particles triggering an inflammatory response. Long-term heat stress may activate a mechanism in the small intestine to maintain homeostasis between commensal bacteria and the immune system. Presan helps stabilise gut microbiota, strengthen gut barrier integrity and support gut health during heat stress. Research shows Presan’s effects on weight gain and gut barrier function (Figure 2) compared to control groups. Trouw Nutrition invests in research to understand the underlying mechanisms of heat stress and develop effective management and nutritional approaches. As climate changes influence animal production, preventative strategies are essential.
References available upon request
Figure 2 - Presan reduced pro and inflammatory cytokines in heat stressed piglets which are messenger molecules of the immune system indicating inflammation.
120
100 80 60
40 20 0
Control Presan p<0.1
120 100 80 60
40 20 0
Control Presan ▶ HEAT STRESS | MAY 2021 37
p<0.05
MDA (nmol/ml)
PHOTO: SHUTTERSTOCK % change in IL-1ß
% change in IL-8
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