Reducing Nematopsis spp Infection of Panaeus Vannamei Shrimps Post Larvae by Using a Mixture of Natural Antimicrobials

The aim of this study was to evaluate the use of a mixture of natural antimicrobials (maltodextrin, sodium chloride, citric acid, sodium citrate, silica, malic acid, citrus extract, and olive extract) to prevent Nematopsis spp. infestation of shrimp and to explore the biological mechanisms involved in preventing infection and improved performance. Our results show that the natural antimicrobials were able, in vitro, to reduce (p < 0.0001) the ability of N. messor, N. quadratum and N. annulipes to adhere to CHSE-214 epithelial cells. In vivo the natural antimicrobial mixture reduced (p < 0.0001) their gut colonisation, increased the (p < 0.05) shrimp survival rates and (p < 0.05) and also the relative growth rate and shrimp size. Moreover, the average daily gain, the total weight gain and the feed conversion rate were all improved over the 30 d trial. The beneficial effects on shrimp performance were associated with a significant increase (p = 0.0004) in the abundance of probiotic-like bacteria (Lactobacillus spp.). This positive change in gut bacterial composition was correlated with a significant increase in the expression of genes related to digestion or the immune response suggesting that natural antimicrobials can improve the performance of shrimp in vivo.