Effect of cyclical feeding on compensatory growth, nitrogen and phosphorus budgets in juvenile Litopenaeus vannamei

This study assessed the effect of cyclical feeding on compensatory growth, nitrogen (N) and phosphorus (P) budgets of juvenile Litopenaeus vannamei. A 36-day growth trial was performed with four different feeding protocols. The control group (S0) was fed to satiation twice every day during the whole experimental period; treatment groups S1, S2 and S3 were fed by the 9, 5 and 3 cycles of 1: 3, 2: 5 and 3: 9 (fasting days: feeding days) respectively. Fasting in S1, S2 and S3 groups did not change the specific growth rate in wet weight (SGR(w)), but the feed conversion efficiency (FCE) and protein efficiency ratio (PER) were significantly increased (P < 0.05) in comparison with control. The N and P consumed per unit wet weight gain of shrimp in S1, S2, S3 groups were significantly lower (P < 0.05) than control group by 15.39%, 15.96%, 19.33% for N, and 15.16%, 15.98%, 19.26% for P respectively. The total discharge of N and P (including N and P discharged by faeces (F-N/P), non-faecal excretions (U-N/P) and exuviations (E-N/P); Sigma(FN/P) + U-N/P + E-N/P) was significantly lower (P < 0.05) in the experiment groups by 19.91-22.07% for N and 18.68-26.37% for P respectively. Overall, the results suggest that the L. vannamei can reach completely compensatory growth, and the total discharge of N and P per unit wet weight gain of L. vannamei significantly decreased by cyclical feeding, which could have a positive effect on the reduced of environmental N and P loading due to the cultured of L. vannamei.