Effects of Starvation on Body Chemical Composition and Energy Density in Juvenile Nile tilapia (Oreochromis niloticus)

40 specimens of juvenile Nile tilapia (Oreochromis niloticus) (initial weight: (3.61±0.13) g) were divided into 5 groups, and were starved for 0, 8, 15, 22 and 45d respectively. Body chemical compositions were measured and energy density was estimated during starvation. The results showed that the contents of protein (PRO), lipid (FAT) and energy density (E) are negatively related to starvation. The relationships between PRO, FAT, or E and starvation time (t, unit: d) could be described as: PRO=14.727e0.0065t (r2=0.707, n=37, p<0.05)、FAT=2.295 5e0.0366t(r2=0.552, n=37, p<0.05) and E=4.478 1e0.0113t(r2=0.694, n=37, p<0.05) The contents of water (WAT) and ash (ASH) are positively related to starvation. The relationships between WAT or ASH and t could be described as: WAT=76.196 9e0.0013t(r2=0.566, n=37, p<0.05) and ASH=4.467 8e0.0083t(r2=0.729, n=37, p<0.01); the contents of protein (PRO), lipid (FAT) and energy density (E) are negatively related to the contents of water (WAT), the relationships between PRO, FAT or E and WAT could be described as: PRO=61.969 9 0.625 1WAT(r2=0.740, n=37, p<0.05)、FAT=47.908 8 0.593 8WAT (r2=0.899, n=37,p<0.05) and E=33.548 9 0.382 1WAT(r2=0.955, n=37, p<0.05). Lipid was mainly consumed during short term starvation and the net consumption gradually reduced with prolonged starvation, and protein was also consumed throughout the whole starvation process.