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This Article Full Text Full Text (PDF) All Versions of this Article: jas.2007-0229v1 86/7/1598    most recent Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Pomar, C. Articles by Jondreville, C. Search for Related Content PubMed PubMed Citation Articles by Pomar, C. Articles by Jondreville, C.

The effect of microbial phytase on true and apparent ileal amino acid digestibilities in growing-finishing pigs^1,2

C. Pomar^*,3, F. Gagné^*, J. J. Matte^*, G. Barnett^* and C. Jondreville

^* Agriculture and Agri-Food Canada, Sherbrooke, Québec, Canada, J1M 1Z3; and and Institut National de la Recherche Agronomique, USC340 Animal et Fonctionnalités des Produits Animaux, Institut National Polytechnique de Lorraine-Ecole Nationale Supérieur d’Agronomie et des Industries Alimentaires, BP 172, F-54505 Vandoeuvre-les-Nancy, France

³ Corresponding author: pomarc{at}agr.gc.ca

Ten 56-d-old, 15-kg barrows were surgically fitted with a postvalvular T-cecum cannula at the ileo-cecal junction to evaluate the effect of microbial phytase on apparent and true ileal AA digestibility and N utilization. A semipurified cornstarch- and soybean meal-based diet was formulated to contain 3.4 Mcal of DE/kg, 17.0% CP, 0.8% Ca, and 0.6% P but had a low phytate-P concentration (0.13%; all on an as-fed basis). Chromic oxide and dysprosium chloride were used as indigestible markers. The basal diet was supplemented with 0 or 1,000 phytase units/kg of microbial phytase. Postprandial plasma urea N and -amino N concentrations, excretion of Ca, P, and N in feces and urine, and ileal AA digestibilities were determined 3 times at 4-wk intervals beginning at 70 d of age. The homoarginine (HA) method was used to determine endogenous AA flow by replacing 50% of the basal protein with guanidinated protein. Microbial phytase had no effect on apparent ileal digestibility (AID) or on true ileal digestibilities of N and most AA but did increase AID for arginine (P = 0.006) and methionine (P = 0.037). However, in HA diets, phytase increased the AID of CP (P = 0.01) and several AA. Addition of microbial phytase had no effect on the postprandial -amino N concentrations in plasma but increased overall plasma urea N concentrations (P = 0.035). Barrows fed phytase-supplemented diets had decreased P in feces (P = 0.003) and greater P in urine (P = 0.001) but comparable total P excretion compared with barrows fed no phytase-supplemented diets. In conclusion, the addition of phytase to a semi-purified soybean meal-based diet did not affect the AID of several AA. In addition, differences between the basal and HA diets in N digestibilities indicated that that guanidination may limit the use of the HA method in determining endogenous protein losses.

Key Words: amino acid • apparent ileal digestibility • homoarginine • phytase • pig • true ileal digestibility