Effects of biofloc on growth performance and survival of Pacific white shrimp (Litopenaeus vannamei) through C/N ratio manipulation, probiotic supplementation, and cocultivation time: A meta-analysis

Biofloc technology (BFT) is recognized as a sustainable approach for enhancing growth and boosting immune responses in the superintensive farming of Pacific white shrimp (Litopenaeus vannamei). The variability in the productive outcomes of BFT has been primarily attributed to the carbon to nitrogen (C/N) ratio, with the participation of probiotic supplementation and the period of cocultivation. We aimed to comprehensively evaluate these factors using key growth indicators (average daily gain, ADG; feed conversion ratio, FCR), as well as a health and water quality indicator (survival rate, SR). Herein, we searched PubMed and ScienceDirect (articles published up to December 5th, 2023; restricted to English) and screened relevant trials. Of 227 identified studies, 8 met our inclusion criteria, yielding 23 records for ADG, 16 for FCR, and 19 for SR. Considering the uniform unit and potentially excessive weight from individual studies, we used a random-effects model to calculate weighted mean differences (WMDs) and 95% confidence intervals (CIs). Regression analysis revealed no significant effects of the C/N ratio or duration on either the growth or health of L. vannamei (Pregression > 0.05). However, probiotic supplementation significantly affected the ADG (Pregression < 0.05) and FCR (Pregression < 0.05) and exhibited a positive trend for the SR (Pregression = 0.100). Meta-analysis further showed that bioflocs without probiotic addition did not affect the ADG, FCR, or SR (P > 0.05). When bioflocs were supplemented with probiotics, the ADG increased by 0.066 g/d (95% CI: 0.044 to 0.088, P < 0.05), the FCR decreased by 1.121 (95% CI: −1.486 to −0.755, P < 0.05), and the SR increased by 9.272% (95% CI: 1.348 to 17.196, P < 0.05). Our findings revealed that the reliable growth and survival benefits of biofloc on L. vannamei are dependent on the exogenous supplementation of probiotics. The manipulation of the C/N ratio may alter the microbial community but does not impact the effects of bioflocs on the rearing system. Bioflocs develop quickly and deliver prompt benefits to shrimp. Further research should focus on screening effective probiotics and exploring their application strategies.