INCLUSION OF WHEAT BRAN IN BARLEY-SOYBEAN MEAL DIETS WITH DIFFERENT PHOSPHORUS LEVELS FOR GROWING-FINISHING PIGS .2. PERFORMANCE AND BONE MINERALIZATION IN GROWING-FINISHING PIGS

The experiment was conducted to study whether wheat bran (WB) phytase could improve the availability of intrinsic phosphorus (P) in commercial barley-soybean meal diets enough to replace the added inorganic P partly or completely in the diets of growing-finishing pigs (30-100 kg). Performance as well as certain chemical and physical parameters of the tibia and fibula bones were used as criteria for the WB phytase effect. The experiment was conducted using a 2x3 factorial arrangement. The factors were wheat bran (WB) level - either 0 (WB-) or 100 g/kg (WB+), and phosphorus level - high (HP), medium (MP) and low (LP) corresponding to 4.33 g, 2.99 g and 1.64 g digestible P per a feed unit (FU = 0.7 kg starch equivalent), respectively. The measured digestible P contents of the diets were 4.2,4.2, 2.7, 2.5, 1.4 and 1.8 g/kg DM, respectively. A content of 2.5-2.7 g of digestible P/kg DM in the diet proved to be sufficient for the whole growing period, but the lowest phosphorus levels led to an impaired growth rate, feed consumption and feed conversion ratio. However, after reaching 60 kg live weight, the pigs on LPWB- and LPWB+ diets were able to grow and utilize feed as effectively as the other pigs. WB at a level of 100 g/kg had no significant effect on the performance, feed conversion ratio or carcass quality criteria of the pigs on any diet. WB phytase showed a positive effect on bone breaking strength on the LP diet.