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UPDATE ON PYTASE AND CHROMIUM FOR USE IN ANIMAL FEED by Sharon A. Benz, Ph.D., PAS Recently, CVM reviewed requests from industry for the use of phytase and chromium picolinate in animal feed. Phytase is an enzyme that hydrolyzes phosphorus bound to phytate in plant-derived feedstuffs. Phosphorus is a critical mineral element required in the diet of all livestock species. Since two-thirds of the phosphorus from cereal grains and forages is in the form of phytates, which is unavailable to non-ruminant animals (e.g., swine and poultry), inorganic phosphates are commonly added to diets to satisfy the animals' phosphorus requirement. Recent studies have shown that the addition of the enzyme, phytase, to swine and poultry diets can release the phosphorus bound to phytate and increase the amount of phosphorus available to the animal. The addition of phytase to the diet should allow producers to reduce the amount of inorganic phosphorus added to animal diets and also reduce the amount of phosphorus in the manure and entering the environment. On November 17, 1995, CVM stated it would not object to BASF marketing a microbial-derived phytase enzyme, which was obtained from bioengineered Aspergillus niger. This product was already marketed in other countries by BASF under the trade name, Natuphos ® . CVM reviewed information to show that Natuphos ® increases the digestibility of phytin-bound phosphorus in swine and poultry diets. Current recommended use levels are 100 g/ton for swine, 60 g/ton for laying hens, and 120 g/ton for other classes of poultry. Based on information to date it is recommended that use of phytase could replace 0.1 - 0.12 percent of phosphorus in the diet. Chromium is a trace element generally present in diets in very small quantities. It serves as a cofactor for insulin and is involved in carbohydrate and lipid metabolism. Although the animal's requirement for trace elements can often be met from amounts present in the diet, because of wide variations in concentrations of trace elements in feedstuffs, trace elements are often supplemented to ensure an adequate intake. Chromium has been recognized as an essential trace element by humans for many years, but chromium supplementation to animal diets has only recently received attention. Information submitted to CVM by Prince Agri shows that chromium picolinate can serve as a bioavailable source of chromium for swine; and on January 11, 1996, CVM notified Prince Agri Products, Inc., Quincy, IL that they would not object to the marketing of chromium picolinate in swine diets at a level of 200 ppb. The chromium picolinate premix will be marketed under the trade name of Chromax ® and the amount of chromium from chromium picolinate will be guaranteed on the labeling. In its decision, CVM considered only chromium picolinate. Presently, there is not sufficient information available to demonstrate the safety and utility (1) for supplementation of other sources of chromium in swine diets or (2) for the use of any source of chromium in diets for species other than swine. Definitions for both microbially-derived phytase and chromium picolinate will be established in the Official Publication of the Association of American Feed Control Officials (AAFCO). Any manufacturer of microbially-derived phytase and chromium picolinate products that meet the specifications of the AAFCO definitions may also market its products.
prev | next Source: May/June 1996 FDA Veterinarian Newsletter |
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