The importance of inorganic phosphates in nursery pig feed

Three feeds were used in this study. In two of them part of the phosphorus was supplied by inorganic feed phosphates.Microbial phytase was included in the third feed. 360 pigs, from 12 to 25 kg, were used for growth trial, per treatment 60 gilts and 60 castrates males. For phosphorus balance trial, 120 pigs from 15 to 25 kg, are used, per treatment 4 pens with each ten piglets. The feeds were pelleted at 80°C.Pelleting at 80°C resulted in pratically no phytase activity in the raw materials and a 60 % decrease of phytase activity from microbial phytase added in treatment 3. The growth are better with inorganic phosphates principally with castrate males.As regards the balance, the quantity of excreted phosphorus was the lowest for treatment 3 (with phytase). The highest amount of retained phosphorus was found with diets 1 and 2 (inorganic phosphates). This resulted in 10 % higher bone phosphorus content with dicalcium phosphate and a 5 % higher content with monocalcium relative to the diet with phytase.