APPARENT DIGESTIBILITY AND RETENTION OF NUTRIENTS BOUND TO PHYTATE COMPLEXES AS INFLUENCED BY MICROBIAL PHYTASE AND FEEDING REGIMEN IN PIGS

Five barrows of approximately 45 kg BW, fitted with post-valvular T-ce cum cannulas at the ileo-cecal junction, were assigned randomly to fiv e treatments (5 x 5 Latin square design) to assess the effect of micro bial phytase and feeding regimen (frequency and level) on the apparent digestibilities (total tract [ATTD] and ileal [AID]) and retention of nutrients. A corn-tapioca-soybean meal diet of low intrinsic phytase activity, containing no added inorganic P, was fed either without or w ith microbial phytase from Aspergillus niger var. Van Tieghem (800 phy tase units/kg of diet) at different feeding frequencies (once, twice, or seven times per day) and feeding levels (2.3 vs 2.8 times the maint enance requirement for ME, i.e., 418 kJ ME/BW.75). Microbial phytase e nhanced significantly the ATTD of DM, OM, CP, Ca, total P, and amino a cids (except for cystine and proline). Also, the AID of total P, phyti c acid, methionine, and arginine was increased (P < .05 or .01). As a consequence of adding this enzyme, the retention (grams/day) of N, Ca, and P was greater (P < .01) and their daily excretion was diminished by 5.5, 2.2, and 1.9 g/d, respectively. The feeding level exerted a mi nor effect on the ATTD and AID (except for methionine and cystine), al though the retention (grams/day) of N, Ca, and P was greater ( P < .01 ) at the higher level of feeding. The feeding frequency influenced sig nificantly the ATTD of Ca, tryptophan, and isoleucine and the AID of p hytic acid, cystine, arginine, isoleucine, and phenylalanine. Also, N retention (grams/day) was reduced in pigs fed once daily (P < .01).