Efficacy of phytase in improving the bioavailability of phosphorus in soybean meal and corn-soybean meal diets for pigs.
Four experiments involving 225 pigs were conducted to assess the efficacy of a microbial phytase (FINASE, Alko Ltd. Biotechnology, Rajamäki, Finland) produced by Aspergillus niger in corn-soybean meal or dextrose-cornstarch-soybean meal-based diets. In two experiments with growing-finishing pigs, fortified corn-soybean meal diets were formulated to be adequate (.50%) or inadequate (.40 or .30%) in P during the growing phase followed by adequate (.40%) or inadequate (.30%) P in the finishing phase. Mono-dicalcium phosphate was the source of supplemental P. Half the diets were supplemented with phytase (500 phytase units/g). Rate and efficiency of gain and bone breaking strength were decreased when P-deficient diets were fed. Phytase supplementation of the low-P diets restored growth rate and feed:gain to levels that approached those of pigs fed the adequate-P control diet. Bone strength was partially restored to that of the controls. In two additional experiments, pigs were fed low-P basal diets in which all the dietary P came from soybean meal or a corn-soybean meal blend. Both diets contained .05% available P. Graded levels of monosodium phosphate were added to these diets, up to .15% added P, to establish a standard curve. Phytase was added to the basal diet at 250, 500, or 1,000 units/g. Growth rate and bone strength improved linearly (P < .01) with added monosodium phosphate and with increasing levels of supplemental phytase. Based on estimates of total and available P intakes, the highest level of phytase (1,000 units/g) increased the bioavailability of the P from 25% in the soybean meal diet to 57% in the phytase-supplemented diet, and from 15% in the corn-soybean diet to 43% in the phytase-supplemented diet. Expressed on the basis of the improvement in phytate P availability, this level of phytase converted approximately one-third of the unavailable P to an available form. The results indicate that the phytase was efficacious in improving the bioavailability of phytate P for pigs.
Cromwell
G L
GL
Department of Animal Sciences, University of Kentucky, Lexington 40546.
Stahly
T S
TS
Coffey
R D
RD
Monegue
H J
HJ
Randolph
J H
JH
D010832:6-Phytase / Q000378:metabolism*; D000821:Animal Feed; D000818:Animals; D001234:Aspergillus niger / Q000201:enzymology*; D001682:Biological Availability; D015519:Bone Density; D005260:Female; D008297:Male; D010758:Phosphorus / Q000172:deficiency / Q000493:pharmacokinetics*; D011897:Random Allocation; D013025:Glycine max; D013552:Swine / Q000378:metabolism*; D015430:Weight Gain; D003313:Zea mays
D010758:Phosphorus; D010832:6-Phytase