A Study on the Effect of Temperature Training on Compensatory Growth and Pathogen Resistance of Post-Larval Litopenaeus Vannamei

The technology of post-larval farming is increasingly being valued by aquaculture farmers and enterprises. The objective of this study is to determine an appropriate temperature restriction mode through temperature training to achieve greater compensatory growth potential. We cultured PL whiteleg shrimp (Litopenaeus vannamei) at either low (25℃) or high (31℃) temperature for 20 days (restriction stage) and then transferred them to a control temperature (28℃) for 20 days (compensation stage). The compensatory growth observed under low temperature restriction showed that shrimp can recover and exhibit over-compensatory growth after growth restriction. Specific growth ratio and enzyme activity analyses indicated that the shrimp required 10 days or more to adapt to temperature stress. The relative expression levels of hsp60, tor, and s6k in the low temperature group were downregulated during the early stage of the restriction period, but were continually upregulated during the compensation period. This result indicates that although short-term restrictions may lead to growth retardation, growth will resume as the temperature recovers. When shrimp were challenged with Vibrio parahaemolyticus E1, the damage caused by infection after low temperature restriction and compensation was delayed and not severe. This indicates that the disease resistance of shrimp was improved after low temperature restriction. In contrast, shrimp in the high temperature group showed more severe damage than those in the control group at all time points after pathogen infection, indicating that high temperature restriction made the shrimp more susceptible to pathogenic Vibrio. Transcriptome analysis revealed abundant pathways related to energy metabolism, amino acid biosynthesis, protein synthesis, and cell growth in the low temperature restriction-recovery group, which highlighted the importance of optimizing the nutrient supply, especially protein and amino acid to enhance compensatory growth. In summary, after 20 days of low temperature training, PL shrimp exhibited significant compensatory growth, which not only promoted the growth, but also enhanced the body’s resistance to V. parahaemolyticus. Therefore, this culture technique can be used for aquaculture practices in PL shrimp cultivation.