PS3-3. Effects of Simultaneous Supplementation of 3-phytase and 6-phytase on Phosphorus and Calcium Digestibility in Growing Pigs

The objective of the present work was to determine the effects of supplemental 3-phytase, 6-phytase, or both on total tract digestibility of phosphorus (P) and calcium in corn-soybean meal-based diets fed to growing pigs. Twelve barrows with an initial body weight of 63.1 kg (standard deviation = 3.0) were individually housed in metabolism crates. A triplicated 4 × 3 incomplete Latin square design with 12 animals, 4 experimental diets, and 3 periods was employed to obtain 9 observations for each experimental diet. The experimental diets comprised 1) a control diet based on 73.3% corn and 23.0% soybean meal without inorganic P source or supplemental phytase, 2) the control diet supplemented with 1,000 phytase unit (FTU)/kg of 3-phytase, 3) the control diet supplemented with 1,000 FTU/kg of 6-phytase, and 4) the control diet supplemented with both 3-phytase at 500 FTU/kg and 6-phytase at 500 FTU/kg. Each period consisted of a 5-d adaptation period and a 5-d collection period, and the marker-to-marker procedure was employed for the quantitative collection of feces. Supplemental phytase reduced (P < 0.05) the daily P output from pigs regardless of the phytase source or the combination of the 2 phytase sources. The pigs fed the diet supplemented with 6-phytase or both 3-phytase and 6-phytase had less daily P output compared with those fed the diet supplemented with only 3-phytase (P < 0.05). The total tract digestibility of P in pigs fed the diet supplemented with both 3-phytase and 6-phytase was greater (P < 0.05) than those fed the control diet or the diet supplemented with only 3-phytase. The apparent total tract digestibility of calcium in pigs fed the diet supplemented with 6-phytase or both 3-phytase and 6-phytase was greater compared with the control group (P < 0.05). In conclusion, supplemental phytase increased P digestibility in corn-soybean meal-based diets fed to growing pigs regardless of the phytase sources and the effects of supplemental phytase on the P and calcium digestibility were most pronounced in the mixture of 3-phytase and 6-phytase.