ISSUE FOCUS FEED & ADDITIVE MAGAZINE May 2024 61 tion due to its potential impact on animal nutrition and overall performance. EFSA is actively exploring the scientific evidence surrounding the utilization of chelated trace minerals in both food and feed. This investigation addresses aspects such as safety, bioavailability, and the potential health and nutritional effects of these minerals in humans and animals. In considering the absorption mechanisms of chelates, there is a theoretical proposition that suggests their absorption via amino acid or peptide transporters. Taking Zn as an example, ZIP4 (Zrt/ Irt-like Protein 4) serves as the major active apical transport mechanism from lumen to enterocyte. However, ZIP4 expression tends to be downregulated if there is a sufficient or oversupply of Zn to prevent excessive Zn absorption, thereby maintaining Zn homeostasis. When there is an excess of free Zn ions in the cytosol of the enterocyte, ZnT1 is activated as a response to maintain Zn balance. This activation is regulated by Metal Transcription Factor 1 (MTF1). ZnT1 works by transporting Zn across the basolateral membrane of the enterocyte, directing it toward the circulation and preventing an accumulation of Zn within the cell (Goff, 2018 and Windisch, 2002). If chelated Zn is indeed absorbed intact, it poses a risk of toxicity. A chelator with such strength that even the metal transporters at the apical gut mucosa (which are strong chelators themselves) cannot extract its metal would fail to dissociate within the enterocyte cytoplasm, leading to uncontrolled accumulation. However, all available data to date suggests that Zn from both chelated and inorganic sources is subject to homeostatic regulation, which strongly suggests that both deliver ionic Zn to the respective molecular machinery. In the animal nutrition industry, various chelated Zn sources have been marketed for their claimed superior bioavailability over traditional sulfates. However, it is crucial to highlight that EFSA's opinions have not definitively concluded on this matter. To date, EFSA's scientific evaluations consistently challenge these claims of higher bioavailability for chelated Zn sources compared to standard sulfates (Table 1). An optimal chelating agent should possess a stability constant that can balance effective sequestration from feed materials and efficient uptake by the animal. CONCLUSIONS While chelating agents aim to improve absorbability, the animal has a pivotal role in downregulating transport pathways, especially when the trace mineral requirements are already met. Regardless of the source, all forms of trace minerals face instability at low pH, including chelates, as at least some of them are partially dissociated and then re-chelated at a higher pH environment. Moreover, in modern conditions with phytase-supplemented diets, bioavailability studies performed in the past decades without phytase should be reevaluated. Among trace mineral forms, sources with slow dissolution kinetics along the acidic segment of the GIT must be considered, as they can affect the bioavailability of trace minerals. Moreover, to ensure proper trace mineral availability determination, they were best studied under subclinical deficiency as the most common Zn-malnutrition phenotype. High Concentration Flowability Safety standards Stability Bioavailability Animal performance POTENTIATED ZINC PURIFIED MANGANESE an international and independent supplier of Precision Minerals , www.animine.eu POTENTIATED ZINC BY PLAYING WITH UNIQUE MINERAL SOURCES! WIN THE GAME 75% MONOVALENT COPPER MONOVALENT COPPER PURIFIED MANGANESE
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