27 Effects of particle size and trace mineral source on vitamin stability in premix

Trace minerals and vitamins are necessary in diets for multiple physiological processes related to structural development, catalytic and regulatory systems in the animal. They become especially important when animals are challenged. These ingredients are commonly added to commercial diets through a concentrated mix, a premix. Unfortunately, vitamins are relatively unstable, and minerals are highly reactive, leading to reduction of the vitamins by the minerals. Feeding a mineral of a different particle size can influence this mechanic, as well as a different source, for example hydroxy trace minerals. The objective of this work was to evaluate vitamin A stability in presence of different sources of trace minerals as well as premix conditions. A microcrystalline cellulose matrix was created by dissolving vitamin A in an organic solvent (IPA). A fixed amount of vitamin MCC mix was added to a sample tube per analysis, containing common premix vitamin and mineral levels. Fixed amount of moisture and antioxidant (BHT) was added to evaluate these effects. Results on the effect of moisture indicated that 10% moisture addition had a large effect on vitamin A stability, reducing it by over 50% after 11 d. Vitamin A loss in premixes containing no moisture showed no difference between MCC mixes containing no mineral and ones containing hydroxy Cu, whereas there was a significant drop in vitamin A with CuSO4. Vitamin A stability was significantly affected by a lower particle size Cu source, with CuSO4 below 75 µm showed almost full degradation after 13 d. Hydroxy Cu showed relatively low degradation for its particle size. Overall, the results showed that moisture and particle size can have a huge impact on vitamin A stability, with BHT or antioxidants only partly being able to reduce this. Feeding a higher quality trace mineral source such as hydroxy trace minerals lead to a less reactive Cu, and hence, a higher vitamin A stability.