Secondary Effects of Phytase?

Nutritionists have found that supplementing with microbial phytase generally improves the digestibility and utilization of phosphorus in feedstuffs of plant origin. The effects of phytase supplementation on amino acid digestibility have been examined and results have been found to be inconsistent. A Canadian study investigated the effects of supplementing 2,000 units/kg phytase (Natuphos) on the digestibility of protein and energy in the diets of growing swine. Diets were formulated to contain 18% crude protein and either low (0.22%) or high (0.48%) phytate phosphorus. Eight barrows, weighing 40.6 kg, fitted with a T-cannula at the distal ileum, were fed four diets in a replicated 4x4 Latin square design. Results indicated that apparent ileal digestibilities of gross energy, crude protein and amino acids and the apparent total-tract digestibilities of gross energy and crude protein were less in the high-phytate diets compared to the low phytate diets (P>0.01). With the exception of glutamic acid, supplementing with 2,000 units of phytate did not affect (P>0.10) the apparent ileal digestibilities of crude protein and amino acids. There was no effect (P>0.05) of phytase on the apparent total-tract digestibilities of crude protein and gross energy.

Liao, S.F. and co-workers. 2005. Effect of phytase supplementation to a low- and a high-phytate diet for growing pigs on the digestibilities of crude proteins, amino acids and energy. J. Animal Sci. 83(9): 2130-2136.