The effects of temperature, moisture, duration of incubation time, calcium level, and soaking with water or citric acid on in vitro phytate degradation in a wheat-barley-rye-soybean meal-based diet

Three in vitro experiments were carried out to determine the effect of temperature, moisture content, duration of incubation, Ca level, soaking with water or citric acid onphytate degradation in a wheat-barley-rye-soybean meal-based broiler diet. In experiment 1, phytase activity of individual feed ingredients and 4 low-P broiler diets, containing 2, 4, 8, and 12 g Ca per kg diet, respectively, were measured in the presence or absence of sodium phytate or soybean meal. By using sodium phytate as substrate, phytase activity of rye, wheat, barley and soybean meal was 3350, 1170, 580 and 30 FTU/kg, respectively (P0.05). In experiment 2, the effect of 2 moisture levels (0.25 and 50%), 3 temperatures (70,75 and 80 degrees C) and 3 durations of incubation (2, 4, and 8 min) on the residual phytase activity of diet 1 (basal diet) were evaluated as a 2 x 3 x 3 factorial arrangement with 3 replicates per treatment. The loss of activity of intrinsic phytase increased from 0.25 at 70 degrees C to 0.61 at 80 degrees C (P