Cyclical fasting and refeeding is not an advisable feeding strategy for white shrimp (Penaeus vannamei)

摘要

This study investigated the effects of cyclical fasting and refeeding on growth performance, digestibility, muscle composition and mTOR signaling pathway of Penaeus vannamei . Three feeding strategies were designed: feeding everyday of a week (control); fasting one day and refeeding six days of a week (F1), fasting two days and refeeding five days of a week (F2). Shrimp with initial body weight of 6.52 ± 0.46 g was used for feeding strategy experiments. The stocking density was 20 shrimps (130.4 g biomass) per 100 L seawater. There were no significant differences in growth performance (final weight, weight gain and specific growth ratio), muscle composition (moisture, crude protein, crude lipid and ash contents) and digestive enzyme activity (trypsin, α-amylase and lipase) among three treatments ( P 0.05). However, survival rate of control treatment was significantly higher than that of F1 and F2 treatments ( P 0.05). Feed efficiency (FE) of shrimp in F1 and F2 treatments were higher than that of shrimp in control treatments. The expression level of trypsin in F1 and F2 treatments were significantly up-regulated than that of control treatment ( P 0.05). Both tor and s6k expression levels of F1 and F2 treatments were up-regulated than those of control treatment. These results suggest that the compensatory growth response of shrimp caused by starvation and refeeding may be attributed to the high feed efficiency after starvation and refeeding or the cannibalism caused by starvation, which provides a better source of protein for shrimp and promotes the growth performance of shrimp. However, considering the low survival rate, cyclical fasting and refeeding is not an advisable feeding strategy for P. vannamei .