Precaecal and postileal metabolism of P, Ca and N in pigs as affected by different carbohydrate sources fed at low level of P intake.

Three different carbohydrate sources (cellulose on wood basis, maize starch and apple pectin) in combination with a low phosphorus (P) basal diet were fed to eight pigs fitted with single ileum-T-cannulas in a balance trial. The effects on net disappearance of dry matter, N, P and Ca as well as phytate (IP6) degradation in the intestine were studied. A basal diet and three diets supplemented with 25% of one carbohydrate source were applied in three experimental periods following an incomplete Latin Square design. Animals were housed individually in balance crates. After 15 days of adaptation to the diets, five days of total excreta collection were followed by two days of spot sampling of ileal digesta. The results showed a significantly decreasing effect of cellulose on the precaecal, postileal and total tract digestibility of DM, N and P. Starch reduced precaecal IP6 degradation and P digestibility. The addition of pectin negatively affected the precaecal digestibility of DM, N and Ca as well as the total tract digestibility of P and Ca. Postileally, cellulose and pectin caused a net secretion while starch induced a net absorption of P.