Date of this Version
An experiment was conducted to determine whether there were differences in performance between two commercial sources of phytase when added to corn and soybean meal-based diets prior to pelleting. Pelleted diets investigated for growing-finishing barrows of high-lean-gain-potential included: 1) University of Nebraska recommended formulations; 2) diets formulated to contain 0.1% less available phosphorus than recommended; 3) diets formulated with 500 FYT/kg added phytase from Ronozyme-P®; 4) diets formulated with 750 FYT/kg added phytase from Ronozyme-P®; 5) diets formulated with 500 FTU/kg added phytase from Natuphos®; and 6) diets formulated with 750 FTU/kg added phytase from Natuphos®. Temperature of the pellets for all diets as they exited the die ranged from 150 to 160°F. Pigs fed diets formulated to contain 0.1% less available phosphorus than recommended had slower (P < 0.05) growth, slower daily lean gain, poorer feed conversion, and decreased bone ash and bone breaking strength than pigs fed the University recommended diets. Phytase recovery following pelleting ranged from 74% to 100%. There was no effect of phytase level or source on daily gain, daily feed, carcass lean, daily lean gain, bone ash or bone breaking strength. Pigs fed diets formulated with Ronozyme-P® had improved (P < 0.05) feed conversion compared with pigs fed Natuphos® as the phytase source. These results suggest that phytase is an effective replacement for dicalcium phosphate in swine diets, and that under the conditions of this experiment, phytase can be added to pelleted diets prior to the pelleting process.