EFFICACY OF NATUPHOS(R) IN SORGHUM-BASED DIETS OF FINISHING SWINE

The efficacy of a recombinantly derived microbial phytase (Natuphos 50 00(R), BASF Corp.) was evaluated in sorghum-soybean meal-based diets o f finishing swine. During the 50- to 80- and 80- to 118-kg BW interval s, diets contained .40 and .39% plant P, respectively; control diets f ed during the two weight intervals were supplemented with .08 and .04% inorganic P from dicalcium phosphate. The all plant-P diets were supp lemented with 0, 300, or 500 phytase units (FTU) per kilogram of diet. Supplemental P (P = .09) and phytase (linear, P = .01) increased grow th rate but did not affect feed efficiency. Dietary treatment did not affect quantitative carcass traits, CP, fat, or moisture content of th e loin or taste panel scores of the cooked loin other than a quadratic decrease (P = .02) in connective tissue amount as phytase supplementa tion increased. Apparent ileal and total tract digestibilities of DM, GE, and N were not affected (P > .25) by phytase supplementation, wher eas 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 an d serum P levels increased in response to inorganic P and phytase supp lementation. Pig performance, carcass traits, and bone traits were ess entially equal for the 300 and 500 FTU/kg treatments. These results sh ow that phytase effectively liberates P in sorghum-based diets, and th at 300 FTU/kg (or less) will optimize performance and carcass merit of finishing swine.