Submitted to: ASAE Annual International Meeting
Publication Type: Proceedings
Publication Acceptance Date: 7/21/1999
Publication Date: N/A
Citation: Interpretive Summary: Excess phosphorus being added to the environment in the form of animal feces is of increasing concern, since it can lead to degradation of surface waters. Researchers have shown that when the enzyme phytase is added to poultry and swine rations, it allows the animals to use much more of the phosphorus bound to the feed, eliminates the need and cost of supplementing gphosphorus, and results in the phosphorus content of the feces being reduced to less than half. Phytase is currently produced in fermentation vats by the mold, Asperillus niger. However, its use is more expensive than supplementation with phosphorus. In order to reduce these costs, a multidisciplinary team has added a gene from Aspergillus niger to alfalfa, a widely grown forage crop, to cause it to produce phytase. The transgenic alfalfa herbage is then processed to yield either juice or leaf meal products for addition to animal rations. Both of these are high in protein and low in fiber, making them compatible with poultry and swine rations, whereas the original herbage is too fibrous. Feeding trials with poultry and swine have verified that alfalfa-produced phytase can completely replace phosphorus supplementation and can result in the phosphorus content of feces being more than halved. Use of alfalfa-produced phytase can reduce costs to animal producers and consumers of animal products while reducing the phosphorus loading to the environment.
Technical Abstract: A multidisciplinary team at Madison, Wisconsin has produced the enzyme phytase in transgenic alfalfa, has converted the herbage to feed supplements for poultry and swine, and has carried out feeding trials to evaluate the efficacy of the phytase. Results showed that alfalfa-produced phytase could completely replace inorganic phosphorus in poultry rations and that the phosphorus concentration of the feces was significantly reduced.