Abstract
An experiment was conducted to test the hypothesis that increasing levels of phytase increases apparent ileal digestibility (AID) and apparent total tract digestibility (ATTD) of nutrients in diets fed to young pigs. A negative control (NC) diet that was deficient (compared with NRC recommendation) in total Ca (-0.15%), standardized total tract digestible P (-0.16%), net energy (-33 kcal/kg), and standardized ileal digestible amino acids (average -0.02% unit) was formulated. Five additional diets were formulated by adding 250, 500, 1,000, 2,000 or 4,000 phytase units per kg of a novel consensus bacterial 6-phytase variant (PhyG) to the NC diet. All diets were based on corn, soybean meal, and canola meal. Eighteen ileal-cannulated pigs (17.81 ± 1.71 kg) were allotted to a 6 × 3 incomplete Latin square design with 6 diets and 3 periods. There were 3 pigs per diet in each period; therefore, there were nine replicate pigs per diet. Data were analyzed using the Mixed Procedure of SAS with diet as the fixed effect whereas pig and period were considered random effects. Linear and quadratic effects of PhyG on nutrient digestibility were determined using polynomial contrast statements. Linear (P < 0.01) and quadratic (P < 0.05) increases in AID of all individual amino acids (except Arg) were observed as dietary concentrations of PhyG increased (Table 1). Likewise, an increase (linear, P < 0.01; quadratic, P < 0.05) in ATTD of minerals in diets was observed as the concentration of PhyG increased in diets. Increasing levels of PhyG in diets also increased (linear, P < 0.05) ATTD of gross energy. In conclusion, increasing levels of the novel phytase (PhyG) effectively increased ileal and total tract digestibility of nutrients by pigs.