| The study is designed to determine the effects of temperature, dietary protein on growth of Portunus trituberculatus, together with an analysis of the bioenegetic mechanisms involved. The primary results of these studies are listed below.1. The parameters of circadian feeding rhythm, feeding frequencies and percent of feeding in daytime and night of juvenile Portunus trituberculatus(Miers)with the body weights of 4.20g and 33.27g was investigated under different crab weights(4.20g and 33.27g).The results showed that there was a pronounced feeding peak occurred at about 2:00 for the crab with the body weights of 4.20g,and the feeding peak displayed at about between 17:00 to 20:00, respectively . The comparison of feeding at night was 59.21% for the small crab, but 73.86% for the big ones. According to the comparison of the ratio of feeding in day and night, it can help us to make better feeding strategies. Feeding clam concentrated in night may make the Portunus trituberculatus grow better. These research results would provide theoretic basis for feeding management and water quality control.2. The effect of temperature on the feeding and growth of juvenile swimming crab Portunus trituberculatus was studied at 18, 21, 24℃. The results showed that:the feeding rate and specific growth rate were correlated positively with water temperature (P<0.05). The feeding rate and specific growth rate in weight were 1.15-4.14% and 1.86-4.65%.The temperature at which the crabs had the maximum feeding rate of 4.14% was 24℃. Its feeding rate and specific growth rate in terms of body weight accumulation increased with temperature between 18℃and 24℃.Water temperature significantly affected the molt frequency and molt weight increment(p<0.05 ) .The days from stage 4 to stage5 at 18℃,21℃,24℃were 16.9d±0.88d;12d±0.58d;8.25d±1.49d respectively. The days from stage 5 to stage 6 at 21℃and 24℃were 15.33d±0.58;12.4d±1.14d respectively .The weight increment at 18℃, 21℃, 24℃were 0.0868g±0.019g, 0.1325g±0.048g, 0.1475g±0.044g respectively. The optimum growth temperature for juvenile swimming crab. wa 21℃.3. The effect of temperature, which was 20,23,26 and 29℃respectively, on the growth and energy budget of Portunus trituberculatus was studied. The results showed that its specific growth rate in terms of body weight and energy accumulation increased with temperature between 20℃and 23℃,and then decreased at 26℃and 29℃.The optimum temperature for the growth of crab was calculated from the relationship of SGR, which was 24.07℃in this study. The food conversion efficiency in weight was decreased with increasing temperature. Absorption efficiency was 53.08%,66.31%,60.45,59.38% respectively and significantly affected by temperature (P<0.05),The energy budget of crab showed that the energy assimilated from food decreased with increasing temperature, while that spent in metabolism increased with increasing temperature. The proportion of excretion was low.4. The protein and fat.component of Portunus trituberculatus with body weight of 56.56 g±3.50g in the overwintering period (2005.12.15-2006.3.15) were measured. The results showed that during the overwintering period, the muscle protein content of Portunus trituberculatus dropped by 5.63 %, the hepatopancreas protein dropped by 4.79%; the muscle fat content dropped by 18.17%, the hepatopancreas fat content dropped by 26.78%. The experimental results show that during the overwintering period Portunus trituberculatus mainly used the fat both in the hepatopancreas and muscle as a major energy source.5. A 40-day growth trial was conducted at 25℃to investigate the effect of different diets on growth and energy budget in swimming crab(Portunus trituberculatus). Swimming crab with the body weight of 31.01g±1.06g were fed with fish, shrimp, and clam respectively. The results showed that specific growth rate (SGR) of wet weight (SGRw), dry matter (SGRdr), protein (SGRp) and energy (SGRe) of the clam group were 2.56%, 2.26%, 3.48%, 0.49% respectively and significantly higher (P<0.05) than the others. Conversion efficiency of wet weight (FCEw), dry matter (FCEdr) protein (FCEp) and energy (FCEe) at clam group were 39.82%±2.09%, 30.18%±1.86%, 33.44%±2.81%, 33.88%±3.09% respectively and .was the highest. Regression analysis showed that the proportions of to various components of the energy budget were significantly affected by diets (P<0.05). The highest proportion of 29.8%±0.9% intake energy for growth and the loest 7.32% for excretion were found at clam group, compaerd with the other two groups 17.93%±3.5% and 18.21%±0.5% for growth,, 12.17%±0.63% and 13.6%±0.18% . for excretion.
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