Meal-feeding and phosphorus ingestion influence calcium bioavailability evaluated by calcium balance and bone breaking strength in pigs.

The 'meal effect' on mineral bioavailability is evaluated in short-term studies on humans whereas feeding experiments on pigs lasting several weeks allow both mineral balance studies and measurements of bone ash contents or breaking strength. Three groups of 7 pigs were given 3 dietary treatments, differing essentially in the mode of Ca and P distribution, for 7 weeks. Group 1 received Ca and P within the meals, Group 2 was fed Ca separate from meals, and Group 3 was given both Ca and P separate from meals. Ca and P absorption were evaluated by a 10-day balance trial, then several bones were collected to determine mineral contents and breaking strength. Ca was much better absorbed and retained by giving CaCO3 within meals. Simultaneous administration of Ca and P did not influence Ca absorption, but tended to improve Ca and P retention. The best bone scores were obtained when CaCO3 and NaH2PO4 were given simultaneously in meals. The Ca and P balance values and bone parameters were strongly correlated. Thus meal incorporation and simultaneous intake of Ca and P are both required for the best mineral retention, evaluated by balance or bone scores.