Pig International - May/June 2017 - 20
20 ❙ PigInternational Organic trace minerals: Getting the most out of phytase In vitro-based research suggests that the use of organic trace minerals can better spare phytase activity when compared to inorganic equivalents. BY MARK GAFFNEY Why more phytase? While the jury may still be out on the actual commercial benefits of superdosing, some published literature does suggest corresponding improvements in feed conversion ratio (FCR) and/ or apparent metabolizable energy when phytase is supplemented at higher than recommended rates. Phytase activity does not respond in a linear fashion; doubling the phytase dose will not result in a doubling of enzyme efficacy. In fact, the numbers indicate that doubling a standard 500 FTU/kg dose will only result in a 30 percent increase in phytase efficacy, and doubling that dose again will halve that efficacy rate. So, if enzyme performance doesn't necessarily go hand in hand with the amount of enzyme added, are there other limiting factors in the feed that are hindering phytase efficacy? Not all phytases are created equal There is a diverse range of phytase enzymes currently on the market, each typically derived from a different biological source. Whether these phytases come from natural fungal fermentations or heterologous expression systems defines their mode of action and dictates how and to what extent phytate can theoretically be hydrolyzed. The effects associated with superdosing may be achieved through extensive phytate hydrolysis, whereby the products of phytase-treated phytate (known as IP esters) are further hydrolyzed. Similar to phytate, IP esters still www.WATTAgNet.com ❙ May/June 2017 Designua | Dreamstime.com Phytase inclusion in monogastric animal diets is commonplace in the industry today, primarily driven by its ability to release phytate-bound phosphorus (P) from cereal-based feed ingredients. The benefits of phytase in monogastric systems have been well documented, with standard rates typically releasing sufficient levels of phytate-P to meet the animal's requirements while simultaneously reducing inorganic P inputs at formulation. More recently, the practice of supplementing phytase in the diet at three to five times the recommended rate, commonly known as superdosing, has been used as a way to promote an extra-phosphoric effect in animals by alleviating the antinutritional effects of phytate in feed.
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