The Pacific white shrimp, Penaeus vannamei, is the most cultivated species worldwide, however, during cultivation, environmental changes can occur that generate stress and alter the normal growth of organisms. When stress is temporary and favorable conditions for growth are restored, shrimp may exhibit an accelerated growth rate known as compensatory growth (CG), which allows them to reach partially or fully the weight of non-stressed organisms. However, if stress is extreme, the CG response capacity may be limited and reach a no-return point. The aim of this study was to evaluate the effect of temperature and temporary fasting periods on the CG response of P. vannamei and to determine gene expression during this process.
Shrimp P. vannamei with an average weight of 0.75 g were exposed to different stress periods with fasting for 3, 7, and 14 days. Simultaneously, each period was analyzed under three temperatures: 22°C, 26°C, and 30°C. Each period was followed by a recovery stage in which feeding and temperature were restored ad libitum and 30°C, respectively, for the remaining time of the 5 experimental weeks. Treatments were evaluated in triplicate and compared with a control group fed to satiety and at 30°C throughout the experiment. Specific growth rate (SGR, % day-1), weight gain (WG), survival (S), food intake (FI), and feed conversion ratio (FCR) were weekly determined and muscle was sampled from all treatments for differential gene expression (DGE) analysis.
Organisms exposed to 3 days of fasting achieved the same weight as those in the control group, which indicated a complete CG, whereas organisms exposed to 14 days of fasting reached the no-return point, being unable to compensate growth and a reduction in WG (>50%) was observed. The SGR and FI were higher in shrimp exposed to 3 days of fasting, however, within this group, FI and FCR were lower at 26°C, suggesting shrimp were more efficient to use the nutrients at this temperature. The DGE with respect to the control group showed over-expressed genes related to the use of stored energy and the molting process during CG (Table 1), whereas genes related to cell damage repair were overexpressed in organisms that reached the no-return point (Table 2).
Penaeus vannamei exposed to 3-day fasting were able to fully compensate their growth and overexpressed genes related to the use of stored energy and the molting process, whereas an extended fasting of 14 days affected their CG response reaching the point of no-return and induced over-expression of genes related to cell damage repair.