It is well known that broiler meat has high-quality protein and low fat content. Thus, the demand for broiler meat has increased, and the broiler industry needs to augment production to respond to higher demand. This aim can be achieved by improving the body weight gain (BWG) and feed efficiency (FE) of broilers. Given the importance of efficiently raising broilers with less feed, we have focused on diet supplements, especially, L-carnitine. L-carnitine is involved in fatty acid metabolism in that it promotes ß-oxidation by acting as a carrier for the transport of long-chain fatty acids from the cytosol into the mitochondria (Metzler, 2003). Research on pig metabolism has shown that body fat decreased with the addition of L-carnitine to the feed (Heo et al., 2000). This contributes to fat oxidation and energy production. L-carnitine can be synthesized endogenously from methionine and lysine (Cox & Hoppel, 1973a, 1973b); however, it is well known that these amino acids are first-and second-limiting amino acids in poultry diets. Furthermore, in general, the amounts of L-carnitine in plant-based feedstuff are low (Borum, 1983; Borum & Broquist, 1977; Mitchell, 1978). Thus, it is unlikely that a diet contains sufficient amounts of L-carnitine as well as methionine and lysine. With respect to de novo synthesis of L-carnitine, it is necessary for a diet to meet or exceed the required levels of methionine and lysine. For these reasons, the addition of L-carnitine to the diet is as necessary as the addition of methionine and lysine. In addition, L-carnitine may affect not only lipid metabolism but also protein

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.