Efficacy of Natuphos in sorghum-based diets of finishing swine.

The efficacy of a recombinantly derived microbial phytase (Natuphos 5000, BASF Corp.) was evaluated in sorghum-soybean meal-based diets of finishing swine. During the 50- to 80- and 80- to 118-kg BW intervals, diets contained .40 and .39% plant P, respectively; control diets fed during the two weight intervals were supplemented with .08 and .04% inorganic P from dicalcium phosphate. The all plant-P diets were supplemented with 0, 300, or 500 phytase units (FTU) per kilogram of diet. Supplemental P (P = .09) and phytase (linear, P = .01) increased growth rate but did not affect feed efficiency. Dietary treatment did not affect quantitative carcass traits, CP, fat, or moisture content of the loin or taste panel scores of the cooked loin other than a quadratic decrease (P = .02) in connective tissue amount as phytase supplementation increased. Apparent ileal and total tract digestibilities of DM, GE, and N were not affected (P > .25) by phytase supplementation, whereas ileal and total tract digestibilities of Ca and P increased (P < .05 or P < .01) with increasing phytase supplementation. Ultimate load and ash content of the third and fourth metacarpals and metatarsals and serum P levels increased in response to inorganic P and phytase supplementation. Pig performance, carcass traits, and bone traits were essentially equal for the 300 and 500 FTU/kg treatments. These results show that phytase effectively liberates P in sorghum-based diets, and that 300 FTU/kg (or less) will optimize performance and carcass merit of finishing swine.