Evaluation of Phytase Enzyme with Chicks Fed Basal Diets Containing Different Soybean Meal Samples

Soybean meal contains approximately 0.62% total P of which 0.4% can be phytate P, which is considered less biologically available for poultry than other forms of P. Soybean meal is a key ingredient in poultry feeds and information is needed about the range of phytate P and nonphytate P in different soybean meals. The phytate P content of soybeans may vary due to climatic conditions, soil type and soybean variety. Previous research has shown that phytate P can be hydrolyzed in the gastrointestinal tract providing available P by adding a commercial phytase enzyme to poultry feed. The extent of phytate hydrolysis by dietary supplementation of phytase has been shown to vary depending on the type of dietary ingredients such as corn, soybean meal, canola meal, and wheat. Research is needed to determine if different commercially available soybean meals respond in a similar manner to a feed added phytase. Twenty-five soybean meal samples were collected from active soybean crushing plants in the United States and 18 of the samples were selected to evaluate the effect of a microbial phytase on phytate P disappearance using 5-d bioassays. The range of analyzed values in soybean meal samples for total P, phytate P, Ca, protein, and neutral detergent fiber (NDF) were 0.59 to 0.87, 0.32 to 0.42, 0.28 to 0.54, 40.44 to 51.69, and 7.78 to 16.09%, respectively. Bioassay results indicate that body weight, feed consumption, and feed conversion ratio improved significantly (P < 0.05) in some of the groups fed diets with enzyme compared with groups fed the same diet with no added enzyme. The range of total P retention and phytate P disappearance for groups fed diets with no enzyme were 21.35 to 48.41 and 13.64 to 37.13%, respectively. The addition of phytase increased total P retention and phytate P disappearance from 56.81 to 68.62 and 76.18 to 94.08%, respectively. The results indicate no correlation among components (total P, phytate P, Ca, protein, and NDF) of soybean meal samples, percentage of phytate P disappearance, and percentage of total P retention for groups fed diets with and without added phytase.