95 Growth Performance, Bone Mineralization, and Nutrient Digestibility of Nursery-grower Pigs Fed Phytase-supplemented Calcium and Phosphorus-deficient Diets
Abstract A 36-d experiment evaluated effects of supplemental OptiPhos Plus phytase (Huvepharma, Peachtree City, GA) on growth, bone mineralization, Ca and P digestibility of nursery-grower pigs. Individually housed crossbred pigs (n = 42; initial body weight [BW], 16.1 ± 0.4 kg) were randomly allotted to 7 dietary treatments based on BW and sex. A positive control (PC) diet was formulated to contain 0.601% Ca and 0.296% standardized total tract digestible (STTD) P, which were marginally lower than NRC (2012) requirement estimates for 25–50 kg pigs. A negative control (NC) diet (0.431% Ca and 0.164% STTD P) was developed by the removal of dicalcium phosphate from the PC diet and replacement with limestone and sand. Diets were: 1) PC, 2) NC, and 3–7) NC + 250, 500, 750, 1,000 and 1,500 FTU phytase/kg diet. On d 36, all pigs were euthanized for femur and metacarpal measures. Compared with NC, pigs fed the PC diet provided greater (P < 0.05) response for ADG (966 vs. 730 g/d), ADFI (1,660 vs. 1,329 g/d); bone measures (37.1 vs. 17.4 g ash/femur and 71.9 vs. 29.3 kg for metacarpal strength), and apparent total tract digestibility (ATTD) of Ca (69.5 vs. 63.5%) and P (62.5 vs. 49.3%). As supplemental phytase increased from 0 to 1,500 FTU/kg of diet, linear and quadratic increases (P < 0.002) occurred in overall ADG and ADFI, femur mineral content, metacarpal breaking strength, and ATTD of Ca and P. Responses statistically similar to PC were achieved at 250 or 500 FTU/kg and peak responses occurred at 750 to 1,500 FTU/kg that were numerically greater than PC for all but metacarpal strength. In conclusion, supplemental OptiPhos Plus improved growth, bone mineralization, Ca and P digestibility of pigs fed Ca and P-deficient diets, demonstrating enhanced Ca and P utilization of corn-soybean meal-based diets by nursery-grower pigs.