Effect of refeeding on the growth and digestive enzyme activities of Fenneropenaeus chinensis juveniles exposed to different periods of food deprivation

The changes in the specific growth rate (SGR), feed intake (FI), feed conversion efficiency (FCE), and digestive enzyme activities (protease, amylase, and lipase in the hepatopancreas) of Fenneropenaeus chinensis juveniles (0.753 +/- A 0.041 g, wet weight) exposed to different periods of food deprivation were investigated during the period of refeeding in a controlled laboratory experiment. The starvation-refeeding cycles consisted of the following seven regimes of 24-day duration: satiate feeding (control, SC); no feeding for 4 (S4), 8 (S8), 12 (S12), 16 (S16), 20 (S20), and 24 (S24) days; then feeding to apparent satiation for the next 20, 16, 12, 8, 4, and 0 days, respectively. The various starvation-refeeding cycles have significant influences on the growth of the test shrimps. The SGR of the shrimps exposed to S4 and S8 treatments exceeded the controls, and no significant differences in SGR (P > 0.05) were found between the SC and S12 or S16 treatments at the end of the refeeding. These changes may have resulted from the significant increase in FI and FCE. The protease activities of test shrimps exposed to different periods of food deprivation were significantly lower (P < 0.05) than those of shrimps under SC treatment at the end of food deprivation then showed a tendency to rapidly increase during refeeding. However, nearly the exact opposite occurred for amylase activities and lipase activities. Lipid and carbohydrate reserves in the hepatopancreas are preferentially mobilized with protein-sparing effect at the beginning of food deprivation. Proteins are the main nutritional store during the refeeding. The findings of the research will be beneficial in the design of feeding regimes and will improve our knowledge on some aspects of the nutrition physiology of F. chinensis related to their biology.