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The study was conducted to evaluate the impact of microbial phytase (0 and 1000 FTU/kg) according to three dietary concentrations of calcium (Ca, 0.50, 0.75 et 1.00%) on the digestive utilisation of phosphorus (P) in weanling pigs. After a 5 day adaptation period under a standard diet, 40 male weanling pigs were blocked by weight and allotted to one of the six dietary treatments in a 29 day experiment. Total collection of urines and faeces were performed between the 15th and the 24th days of the experimental period. At the end of the experiment, the left femur and the digesta of the stomach and of the different parts of the small intestine were removed.
Phosphorus digestibility was improved in diets supplemented with phytase whatever Ca concentration, whereas it was depressed by increased dietary Ca. However, in piglets given diets with phytase, reduction of Ca concentration increased urinary losses of P. The pH of the different segments followed an increasing proximo-distal gradient but did not differ among the treatments. Nevertheless, a negative relation was observed between the gastric pH and the proportion of soluble inorganic P (iP) and Ca. In the same segment, phytase improved iP, especially in low-Ca diets.
In diets with phytase, the decrease in gastric P solubility due to high dietary Ca content did not appear to be a limiting step regarding the enzyme efficacy in ameliorating P digestibility.
A. Narcy, M.-P. Létourneau-Montminy, E. Bouzouagh, N. Même, M. Magnin, J.-Y. Dourmad. Modulation de l'utilisation digestive du phosphore chez le porcelet sevré : influence de l'apport de calcium et de phytase sur le pH et la solubilité des minéraux au niveau gastrointestinal. 2012. Journées Recherche Porcine, 44, 159-164.