Amino acid and mineral digestibility, bone ash, and plasma inositol is increased by including microbial phytase in diets for growing pigs.

Background: The effect of microbial phytase on amino acid and energy digestibility is not consistent in pigs, which may be related to the phytase dosage or the adaptation length to the diet. Therefore, an experiment was conducted to test the hypotheses that increasing dietary phytase after an 18-day adaptation period: 1) increases nutrient and energy digestibility; 2) increases plasma P, plasma inositol, and bone ash of young pigs; and 3) demonstrates that maximum phytate degradation requires more phytase than maximum P digestibility.

Results: Data indicated that increasing inclusion of phytase [0, 250, 500, 1,000, 2,000, and 4,000 phytase units (FTU)/kg feed] in corn-soybean meal-based diets increased apparent ileal digestibility (AID) of Trp (quadratic; P < 0.