Distribution of supplemental Escherichia coli AppA2 phytase activity in digesta of various gastrointestinal segments of young pigs

¹ Department of Animal Science, Cornell University, Ithaca, NY 14853

^* To whom correspondence should be addressed. E-mail: XL20{at}cornell.edu.

	Abstract

The objective of this study was to determine the functional location and activity disappearance of a supplemental E. coli appA2 phytase and its impact on digesta P and Ca concentrations in the gastrointestinal tract of pigs. In Exp. 1, 18 pigs (8.3 ± 0.2 kg BW) were allotted to 3 groups (n = 6) and fed a low-P (0.4%) corn-soybean meal basal diet (BD), BD + phytase (500 units (U)/kg) or BD + inorganic P (0.1%) for 4 wk. In Exp. 2, 30 pigs (14.5 ± 0.2 kg BW) were allotted to 3 groups (n = 10) and fed BD, BD + 500 U/kg or BD + 2,000 U/kg for 2 wk. Five or 6 pigs out of each treatment group were killed at the end of both experiments to assay for digesta phytase activity and soluble P concentration in six segments of the digestive tract and digesta total P and Ca concentrations in stomach and colon. Compared with pigs fed BD, pigs fed BD + 500 U/kg in Exp. 1 and BD + 2,000 U/kg in Exp. 2 had greater (P < 0.05) phytase activities in the digesta of stomach and upper jejunum (2 m aborally from duodenum). No phytase activity was detected in digesta of lower jejunum (2.12 m back from the ileocecal junction) or ileum from any of the treatment groups in either trial. Concentrations of digesta soluble P peaked in the upper jejunum of pigs fed BD in both Exp. 1 and 2, but showed gradual decreases between the stomach and the upper jejunum of pigs fed BD + phytase or BD + iP. In both experiments, pigs fed only BD had greater (P < 0.05) colonic digesta phytase activity and soluble P concentrations than those fed phytase. In Exp. 2, total colonic digesta P and (or) Ca concentrations of pigs displayed a phytase-dose dependent reductions (P < 0.05). In conclusion, supplemental dietary AppA2 mainly functioned in the stomach, and was associated with a reduced phytase activity in colonic digesta of weanling pigs.

Key Words: calcium, colon, digesta, phytase, phytate-phosphorus, pigs