Table 10.

Phytase activity (FTU g⁻¹) of phytase samples measured by different methods^a and its effect on inorganic P release estimations

Phytasesb	Natuphos	Phyzyme	Ronozyme P	OptiPhos
Activity by producer (FTU g−1)	5000	5000	2500	2000
Analyzed by different methods (FTU g−1)c
AOAC (2000)	7300	5000	2800	9300
Danisco	4800	4300	2800	9300
Phytex	4400	1200	1500	1800
Roche	4800	3700	2600	6200
Inorganic P released by 500 FTU (g kg−1)
Based on activity by producer	0.34	0.39	0.28	1.02
Based on activity analyzed by AOAC method	0.24	0.39	0.25	0.22

^a1 FTU is defined as the quantity of enzyme required to liberate 1 µmol inorganic P min⁻¹, at pH 5.5, from an excess of 15 µmol L⁻¹ sodium phytate at 37 °C kg⁻¹ feed.³

^bNatuphos (BASF, Mt Olive, NY, USA); Phyzyme (Dupont/Danisco Animal Nutrition, Marlborough, UK); OptiPhos (Enzyvia LLC, Sheridan, IN, USA); Ronozyme P (DSM Nutritional Products Inc., Parsippany, NJ, USA).

^cEach phytase premix was analyzed by the same lab with different methods (Eurofins Scientific Inc., Des Moines, IA, USA).

Data from Kerr et al.⁸⁸