Opinion of the Scientific Panel on Additives and Products or Substances used in Animal Feed and the Scientific Panel on Genetically Modified Organisms on the safety and efficacy of the enzymatic preparation Phyzyme XP (6-Phytase) for use as feed additive for chickens for fattening

Phyzyme XP is an enzyme feed additive with 6-phytase as its main activity, produced after fermentation with the genetically modified yeast Schizosaccharomyces pombe, designated ASP595-1 and deposited in the American Collection of Type Cultures as strain ATCC 5233. The final production strain is obtained after transformation with a linearised DNA fragment containing eight tandem repeats of an expression cassette which consists of the cytomegalovirus promoter, the 5' untranslated region of human lipocortin1 cDNA, the 6-phytase open reading frame, the terminator and the 3' untranslated region of human lipoprotein1 cDNA. No antibiotic resistance marker sequences were co-transformed as was confirmed by PCR. The expression cassettes are integrated in the leu1 gene of the S. pombe chromosome. The applicant provided an acceptable risk analysis of the introduced viral sequences. Thus, no harmful sequences have been introduced, nor are there any antibiotic resistance marker sequences in the final production strain. The safety of the donor and recipient organisms is based on the concept of familiarity. After fermentation the enzyme is purified and the final enzyme product contains no culturable production organisms and recombinant DNA is below the level of detection. Three pen trials conducted over the 42-day growing period showed significant effects on feed efficiency, daily weight gain and/or feed intake with the supplementation of 500 FTU Phyzyme XP kg(-1) feed. P digestibility was also demonstrated to be increased with 500 FTU Phyzyme XP kg(-1) feed. Only two studies were provided with supplementation of diets with 250 FTU Phyzyme XP kg(-1) feed, both showing significant effects on weight gain, feed conversion and feed intake in two studies and on bone ash in one study. Therefore it is concluded that the efficacy of Phyzyme XP has been demonstrated at the dose of 500 FTU kg(-1), but insufficient data is provided to demonstrate efficacy at the minimum recommended dose of 250 FTU kg(-1). A tolerance test carried out with chickens for fattening over a period of six weeks with the recommended dose (500 FTU kg(-1)) and 7.5-fold overdose (7500 FTU kg(-1)) of Phyzyme XP produced no evidence of any adverse effect on performance or mortality. Therefore it is concluded that the safety of Phyzyme XP has been demonstrated at the recommended dose and the 7.5-fold overdose. On the basis of the results of three genotoxicity studies and one 90-day toxicity study there is no concern regarding the safety of this product for the consumer. The product showed slight evidence of irritancy, low acute inhalation toxicity and no evidence of dermal sensitisation. By convention, the product, being an enzyme, is considered as a potential respiratory sensitizer. It is concluded that there is no evidence for concern regarding safety for the environment.