Feed & Additive Magazine Issue 4 May 2021

SPECIAL STORY 40 FEED & ADDITIVE MAGAZINE May 2021 it is possible to have elevated levels of cadmium in tissues at slaughter time. UNDERSTANDING ZNO MODE OF ACTION TO DESIGN SUITABLE ALTERNATIVES According Prof. Zentek (Univ. of Berlin) inter- viewed in December 2020 by Animine regarding the state-of-the-art research on ZnO, he said: “The mechanisms of action are manifold and refer on the one hand to the intestinal microbiota, but then also to numerous processes in the intestinal mucosa. High doses of zinc oxide have a functional impact on the intestine, they can reduce the secretion of chloride and thus of water. Furthermore, it is in- creasingly shown that also the intestinal barrier and the gut associated and also the general immune sys- tem is affected. Further on, numerous regulatory mechanisms react on different levels of zinc intake. Therefore, these interesting findings are extremely valuable to narrow down the mechanisms of action more precisely and thus to develop considerations on alternatives to the pharmacological dosage of zinc oxide” ZINC: AN ESSENTIAL DIMENSION WHEN CONSIDERING PHARMA. ZNO REPLACEMENT ZnO is the most common source of Zn used in pig feeding. ZnO is known to be variable in the different parts of the world. In North America, the most common source of ZnO used is a dark-brown- ish powder; in Europe standard ZnO is more of a light-brownish product. In Asia, however, ZnO is known as a white powder. These differences go beyond the color and aspect of the powder, it is highly related to their quality, purity and bioavail- ability (see picture 1). The quality of raw material and the method by which ZnO is produced affects they composition (including the presence of heavy metals) and also their physicochemical properties. Particle size and specific surface area, among other characteristics are important in the fate of ZnO in gastrointestinal tract of animal. A recent study at Ghent University, Belgium, scru- tinized the effect of a particular source of potentiated zinc oxide manufactured in Europe (commercialised under the brand HiZox®, picture in the middle be- low). Using a patented manufacturing technology, the physicochemical properties of this nutritional ZnO source are modified to give it a “porous” par- ticle with a very large surface area, 10 to 15 times greater than conventional zinc oxide sources. This larger surface area drastically increases the contact Picture 1: from left to right: Asian ZnO source, EU potentiated ZnO (HiZox(r)) and American ZnO source. Figure 1- Coliform count in distal small intestine (P<0.05). Ghent University (Belgium)