INCLUSION OF WHEAT BRAN IN BARLEY-SOYBEAN MEAL DIETS WITH DIFFERENT PHOSPHORUS LEVELS FOR GROWING-FINISHING PIGS .1. EFFECTS ON NUTRIENT DIGESTIBILITY AND MINERAL BALANCES IN FINISHING PIGS

The effect of the intrinsic phytase of wheat bran (WB) on phytin-phosp horus availability to pigs on barley-soybean meal diets was measured i n a digestibility and balance experiment using a 2x3 factorial arrange ment in a 6x5 cyclic change-over design. The factors were WB inclusion (0 or 100 g per kg, later referred to as WB- and WB+, respectively) a nd three phosphorus (P) levels: high (HP), medium (MP) and low (LP). T he inclusion of WB in the diet did not significantly improve dietary P utilization. However, the absorption and retention of P appeared to b e slightly improved by WB inclusion in the LP diet. This improvement m ay be due to WB phytase. The effects of WB on the digestibility and ba lance of other minerals remained relatively small. The P level, on the other hand, had a greater effect on mineral balances. Ash digestibili ty was not affected by the treatments. Dry matter and organic matter d igestibilities were impaired when WB was included in the diet. N absor ption of intake was higher (p<0.01) on WB+ diets. The retention of N a ppeared to decrease on HP and MP diets due to WB, but on LP diets no d ecrease was observed. Regarding the polluting P-emission, the LPWB+ di et appeared to be the most favourable, since the faecal excretion of P was the lowest and the overall retention coefficient of P was the hig hest. On the basis of these results, an addition of 100 g WB to the di et in order to improve P utilization does not seem very attractive.