Growth Performance and Disease Resistance against Vibrio parahaemolyticus of Whiteleg Shrimp (Litopenaeus vannamei) Fed Essential Oil Blend (Phyto AquaBiotic)

SIMPLE SUMMARY: Plant-derived essential oils are promising preventive supplements as antibiotic alternatives in aquaculture. In this study, an essential oil blend (Phyto AquaBiotic, abbreviated as PAB) was tested in Liptopenaeus vannamei to evaluate its effect on growth improvement and mortality mitigation when infected by Vibrio parahaemolyticus (causative agent of Acute Hepatopancreatic Necrosis Disease). Shrimps were fed with two dosages of PAB for 42 days followed by a challenge against a pathogenic strain of V. parahaemolyticus. Results showed an improvement in growth performance and reduction in mortality compared to the positive control (unsupplemented with PAB and challenged against V. parahaemolyticus). Moreover, the Vibrio spp. count in the hepatopancreas of shrimps fed with 2 g/kg of this blend was markedly lower compared to that of the control. To conclude, 2 g/kg PAB contributes in reducing mortality in the context of AHPND outbreaks in whiteleg shrimp (L. vannamei). ABSTRACT: Acute Hepatopancreatic Necrosis Disease (AHPND) is a serious and emerging disease caused by a group of strains of Vibrio parahaemolyticus and affects farmed shrimp, particularly whiteleg shrimps (Liptopenaeus vannamei). The objective of this study is to assess the effect of dietary supplementation with two dosages of an essential oil mixture (Phyto AquaBiotic, abbreviated as PAB) on growth performance and mortality reduction after challenge against V. parahaemolyticus. PAB was mixed with basal diets at rates of 0, 1 and 2 g/kg and fed for 42 days. Each tank was stocked with 100 individuals with experimentation performed in triplicate. The results showed an improvement in growth performance in a dose-dependent manner, specifically regarding daily weight gain, specific growth rate and total biomass, which were significantly improved compared to control (p < 0.05). Further, PAB significantly reduced mortalities when challenged against Vibrio parahaemolyticus (p < 0.05) and decreased Vibrio spp. count in the hepatopancreas of infected shrimp. Overall, PAB was efficient in reducing mortalities in cases of disease outbreaks at a rate of 2 g/kg.