PSA Nutrition: Phytase and General Nutrition

Ronozyme PTM CT (RCT), a phytase, was developed for improved heat stability for pelleted feeds to avoid the need for liquid phytase application. The patented, thin lipid coating of the beadlet reduces enzyme exposure to moisture, one of the two major destabilizing factors for phytase during pelleting. Retention tests were completed in 12 randomly chosen integrated U.S. poultry commercial feedmills. In each case, a total of 0.4 to 0.6 lbs (181 to 272 grams; no carrier) was added per 2000 lbs (907 kg) of feed. A total of 10-20 samples of mash feed were taken as the feed exited the mixer, while 10-20 samples of pelleted feed were obtained at the cooler. Samples were taken at equal-time intervals based on feed flow rate. The percent RCT phytase remaining was 68 to 90% across pellet temperatures of 163F to 210F (73C to 99C). RCT retention tended to plateau at 70-80%, even at the highest temperatures tested. The mean mixing coefficient of variation (%CV) for phytase was 14.2% in mash, but 12.6% in pelleted feed, an improvement of about 11% in %CV. Mixing during augering and cooling likely accounts for the improved %CV in pelleted feed. RCT phytase retention is no less than about 70% across typical pelleting temperatures, thus serves as a viable, economically attractive alternative to liquid phytase in pelleted feeds. Conditioned mash was 16-17% moisture across mills, and may be the factor that limits RCT phytase destruction at the higher temperatures.