Effects of a rice diet and phytase addition on growth performance, tissue weights, phosphorus and nitrogen retention, and on liver threonine dehydrogenase, malic enzyme and fatty acid synthase activities in broiler chicks.

This experiment was conducted to clarify the nutritional functions of rice and phytase addition for broiler chicks. Thirty-six 7-day-old male chicks (ROSS 308 strain) were assigned to one of the four treatment groups: corn- or rice-based diet groups and each diet with added phytase (2000 phytase units/kg diet) groups (corn + P or rice + P groups). The non-phytate phosphorus (npP) content in the diets with added phytase was approximately half of the requirement. Body weight gain and feed intake in the rice group was significantly higher than those in the corn group. Breast and thigh muscle weights and nitrogen retention in the rice group were significantly higher than that in the corn group. Although the efficiency of phosphorus retention (%) in the corn + P group was significantly higher than that in the corn group, no significant difference was observed between the rice and rice + P groups. Liver threonine dehydrogenase activity in the corn group was significantly higher than in the other three groups. These results indicate that rice is superior to corn as a starter diet in broiler chicks, and that phytase action in the rice-based diet was less than that in the corn-based diet.