Early-stage fasting leads to long-term growth inhibition and body composition changes in turbot (Scophthalmus maximus)

TL;DR

Fasting juvenile turbot early in life causes long-term growth delays and changes in body composition, even after refeeding.

Contribution

This study shows that early fasting in turbot leads to lasting growth inhibition and body composition changes, challenging the effectiveness of compensatory growth strategies.

Findings

Early fasting for 3 to 12 days caused final growth retardation in turbot, with longer fasting leading to greater inhibition.

Fasting increased lipid and glycogen accumulation but reduced muscle protein and amino acid content after refeeding.

Transcriptome analysis revealed that 12-day fasting inhibited protein biosynthesis even after 60 days of refeeding.

Abstract

Stimulation of compensatory growth by refeeding after a period of fasting has been used as an economical strategy of growth and body composition manipulation in aquaculture practice. In this study, a total of 300 turbot juveniles, at 85 d post hatch with an initial weight of 5.53 ± 0.06 g, were randomly allocated to 15 tanks (20 fish/tank). The control group was continuously fed, while the four experimental groups were subjected to fasting for 3, 6, 9, or 12 d, respectively, followed by a 60-d refeeding. Each feeding strategy was applied to triplicate tanks. Fish were hand-fed a commercial feed (containing 54.0% protein, 8.0% lipid, and 21.6 MJ/kg gross energy) to apparent satiation. Sampling was conducted at the end of refeeding. Early fasting for 3 to 12 d resulted in final growth retardation compared to the control. This growth inhibition was closely correlated to the fasting duration. The 12-d fasting group showed significantly lower (P = 0.027) average weight gain (576%) compared to the control group (709%). Early-stage fasting stimulated the lipid accumulation in various tissues (P < 0.05) and the glycogen accumulation in the muscle of fish after refeeding, but reduced the muscle protein and amino acid content (P < 0.05). The feeding strategy treatments exerted only minor effects on the fatty acid composition of final fish tissues. The transcriptome analysis confirmed that fasting for 12 d in the juvenile stage still inhibited the peptide and protein biosynthesis even after 60 d of refeeding (P < 0.05). In conclusion, compensatory growth through fasting was not observed under the current experimental conditions. Early fasting leads to long-term growth inhibition and changes of body composition in juvenile turbot.

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