Feed & Additive Magazine Issue 3 April 2021

ISSUE FOCUS FEED & ADDITIVE MAGAZINE April 2021 37 It is well established in the literature that retention of feed vitamins (such as E, A and certain B complex vi- tamins) over time will vary based on what type of trace minerals were included. For example, feeds containing chelated trace mineral sources retain more vitamin ac- tivity over six months, compared to sulphates. A trial carried out in 2010 examined the stabili- ty of vitamin E in feeds supplemented with no trace mineral, or 200ppm of either hydroxy copper or cop- per sulphate. Researchers found that during a 41-day window, feeds with no supplementation or supple- mentation with hydroxy-copper maintained similar amounts of vitamin E. Feed with copper sulphate lost about 69% of the vitamin by the end of the trial. Hy- droxy copper does not interact with vitamins in feed, meaning more vitamins are left for the animal to use. Similarly, when chicks received diets supplemented with 100, 150 or 200ppm copper sulphate or hy- droxy copper and vitamin E, the amount of vitamin E found in birds’ blood plasma was 11% higher for birds eating feeds with hydroxy copper. MINERAL SOURCE AND PHYTASE FUNCTION Trace mineral copper source can alter how added enzymes, like phytase, function in diets. In an in vi- tro study completed in 2006, researchers examined the interaction between supplemental copper and phytase in feeds. The researchers looked at the use of copper citrate, copper chloride, organic copper or copper lysine, copper sulphate and hydroxy copper at levels including 0, 62.5, 125, 250 or 500ppm. As the amount of copper added to the feed increased, the amount of phosphorous hydrolysis (the amount of phosphorus released from the Phytate molecule) in the diet fell. However, the most extreme negative reactions followed the combination of phytase and copper chloride, copper sulphate and copper citrate. If a high level of one of these types of trace mineral is included in the diet, significantly less Phosphorus could be liberated from the phytate by the activity of the phytase enzyme. This is because Phytate has a high affinity for the soluble trace mineral ions (e.g. Cu2+) which easily dissociate from their ligands (e.g. sulphate) and bind to the phytate, blocking phytase activity. Phytase function remained highest when hy- droxy copper was supplemented. Therefore, the use of a trace mineral source which remains insoluble in feed can minimise interference with phytase function. EXTRA-NUTRITIONAL EFFECTS OF COPPER Copper is required in feed in order to fulfil the ani- mal’s nutritional requirement, which is defined by the amount of Copper available in the small intestine to be absorbed across the intestinal wall. However, by in- creasing the concentration of copper in the lumen of the gut, copper can help to manage the microbiota in the gut, due to its natural bacteriostat- ic properties. Extra-nutrition- al levels of copper (125 to 250ppm) have been linked to improvements in gut integrity and health, feed effi- ciency and growth rate. There may be a number of differ- ent modes of action involved in these Figure 1 – Trial results from studies looking at vitamin stability based on trace mineral type.