Immunity and histopathological changes of shrimp (Litopenaeus vannamei) fed with Melaleuca cajuputi-synthesized gold nanoparticles (MC-AuNPs) supplemented diets at various durations and concentrations

The green synthesis nanoparticles formulated in aquatic feed were commonly studied nowadays to improve aquatic product immunity and mitigate disease occurrence due to their effectiveness, safety, and lower cost. This study was assessed to investigate the effect of Melaleuca cajuputi-synthesized gold nanoparticles (MC-AuNPs) at various concentrations (i.e., 0%, 10%, 40%, and 70%) and feeding periods: short-term (4 days) and long-term (30 days) on immunity and histology of the whiteleg shrimp Litopenaeus vannamei. The selected concentrations used are based on our previous study on the antibacterial properties of MC-AuNP diets against Vibrio parahaemolyticus. Following feeding, shrimps were then challenged with Vibrio parahaemolyticus to assess their resistance and histological alterations. Results showed that the shrimp fed with 10% and 40% MC-AuNP diets for both short-term and long-term feeding periods increased the biochemical and hematological parameters of the shrimp. After the challenge with V. parahaemolyticus, abnormal lumens were seen, while the hepatopancreatic cells and tissue in the 10% and 40% MC-AuNP diets appeared normal. Improved survival rates were observed in all shrimp supplemented with MC-AuNP diets, particularly in 10% and 40%. The findings suggest that the inclusion of 10% and 40% MC-AuNP diets for short-term feeding periods was recommended to be further studied as shrimp immunostimulants due to their potential to improve shrimp immunity with minimal histopathological changes to the shrimp hepatopancreas.