Microbial Phytase and Nutrient Utilization in Low Phosphorus Chicken Diets

Abstract

Experiments were conducted with male growing chicken (Cobb 500) to examine effects of added microbial phytase on growth performance and nutrient utilization in corn-soybean meal (CSM) and wheat-soybean meal (WSM) diets. Low P basal diets (CSM1: 0.15 / 0.11% NPP in DM of starter/grower diets; WSM1: 0.16/0.12% NPP in DM of starter/grower diets) were supplemented with 250 or 500U/kg of an experimental microbial phytase (CSM2, CSM3; WSM2, WSM3) or 1.5g/kg inorganic phosphorus (CSM4, WSM4). Growth studies were conducted (7-42d) to establish nutrient deposition (6 pens per diet, 10 birds per pen). Separate balance studies (n=8) yielded individual N and P balance data for the age period 21-25d. Additionally, studies with CSM diets also provided tibia composition data.
Phytase supplementation in CSM diets yielded significant effects on growth and deposition data. Additionally, the mortality rate declined significantly and tibia composition (ash, P, Ca) was improved. WSM diets provided more pronounced effects on deposition data, but growth responded only numerical. Balance studies delivered significant effects on P utilization due to phytase addition in both CSM and WSM diets, respectively. However, lower P utilization was observed in CSM diets. Significant effects of phytase addition on N utilization were established only in CSM diets. Consequently, generalized conclusions due to improved N utilization following phytase addition are not supported by the current study.