Feed & Additive Magazine Issue 4 May 2021

ARTICLE FEED & ADDITIVE MAGAZINE May 2021 57 to evaluate antioxidants, nevertheless, in vivo trials are necessary to validate solutions. The scientific ap- proach to determine the ideal solution can therefore be split in 2 steps: the evaluation of individual in- gredients and their variability ; and the formulation of optimal ingredients. To illustrate the variability of ingredient, a recent work was achieved (See figure 1) to measure the an- tioxidant activity of phlorotannins from various sea- weeds and various geographic origins. Phlorotannins are a type of polyphenols found in brown algae such as kelps, and that can only be found in seaweeds. In the present example, one can see that between sea- weeds or even for the same species, variability can be very high. The same applies to other plants. This is why formulators need to carefully select the source and the quality of antioxidant to guarantee a consis- tent quality and efficacy in feed. Regarding formulation or the selection of solu- tions, considering the numbers of natural antioxi- dants, this can be a very time-consuming activity, not to say a total waste of time. More importantly, several studies have highlighted the potential syner- gies between different sources of polyphenols (Liu, 2004). When combining polyphenols from 4 differ- ent sources, the dose-response curve of antioxidant activity was shifted to the left and the median effec- tive dose (EC50) of the combination was 5 times lower than the EC50 of each single source, suggest- ing synergistic effects when combining sources. As a matter of fact, combining various sources of poly- phenols looks like the most strategic and most resil- ient approach. STRENGTHENING THE ANTIOXIDANT POOL FOR MORE RESILIENCE Countless studies have shown the potential of nat- ural antioxidants to strengthen or complement the activity of other antioxidants, such as vitamin E, in feed. This effect is well documented, for many com- mercial solutions. The interest for such application is driven by technical and economic considerations and is of high interest in case of price crisis. Recent trials made with an exclusive blend of natural antioxidants, including polyphenols from fruits, vegetables and seaweeds, showed how these solutions could be used to optimize formulations