The influence of dietary microbial phytase and copper on copper status in growing pigs

To determine the effect of supplemental dietary microbial phytase and copper on copper status of growing pigs a 3×3 factorial arrangement of treatments with 72 castrated crossbred pigs covering a body weight range from 23 to 55 kg was conducted. Three levels of phytase (0, 250 and 500 U/kg diet) and three levels of copper (20, 80 and 175 mg/kg diet) were added to diets based on barley and soya bean meal. The addition of microbial phytase to the diets caused a slight increase in copper requirement. Higher dietary copper could overcome the negative effects of phytase on copper availability. As at all dietary copper levels, the zinc content in bone (phalanx 1) increased when phytase was added to the diets; it was concluded that the increase in copper requirement was due to the releasing of zinc from the phytate complex and the forthcoming antagonistic effects of zinc on copper availability.