This study was divided into three parts. In the 1st trial, we adjusted the levels of crude protein included in the diets fed to olive flounder (Paralichthys olivaceus), then we collected body weight data to determine the level of crude protein with the best growth performance. In the 2nd trial, which was based on the results of the 1st trial, we adjusted the levels of crude fat included in the diets, and then collected body weight data to determine the level of crude fat with the best growth performance. In the 3rd trial, we used 2nd trial diets, then we collected fish meat to determine the level of texture and tasting with the best flavor.
In the 1st trial, olive flounder with a mean initial weight of 173.40±1.90g were fed one of five diets with different dietary protein levels of 35, 40, 45, 50 and 60% for 8 weeks, and it was found that the growth performances of the CP50 and CP60 groups were significantly better than that of the CP35, CP40 and CP45 group. The weight gains of the groups were 90.87±2.81%, 93.68±0.62%, 96.28±0.70%, 98.23±0.92% and 99.12±2.32%, respectively, and the specific growth rates were 1.15±0.03%, 1.18±0.01%, 1.20±0.01% , 1.22±0.01% and 1.23±0.02%, respectively. Considering the costs of the diets and the growth performance results, this study suggests that the best dietary protein level is 52%.
In the 2nd trial, olive flounder with a mean initial weight of 333.48±9.19g were fed one of four diets with different dietary fat levels of 5, 10, 15 and 20% for 8 weeks, and it was found that the growth performances of the F15 group were significantly better than those of the other groups. The weight gains were 16.04±0.85%, 23.99±1.31%, 34.55±1.00% and 23.34±0.10%, respectively, and the specific growth rates were 0.27±0.01%, 0.38±0.02%, 0.53±0.01% and 0.37±0.00%, respectively. According to the results of the statistical analysis, t this study suggests that the best dietary fat level is 16%.
In the 3rd trial, olive flounder with a mean initial weight of 1048.00±24.93g were fed one of four diets with different dietary fat levels of 5, 10, 15 and 20% for 8 weeks, the hardness of the raw fish of the dorsal muscle will increase with the increase of the fat content in the feed, but the protein denatures after being cooked, and the texture of the cooked fish is the opposite. The elastic of the dorsal muscle will increase with the increase of the fat content in the feed after the fish is cooked. The ventral muscle has the same hardness trend as the dorsal muscle, while the elastic is the highest in the F15% group in raw fish. The test results showed that the F15% group had the best preference.