The effects of brown algae Sargassum angustifolium extract on growth performance, survival and Vibriosis resistance in shrimp Litopenaeus vannamei

In this study, the effect of ethanolic extracts of Sargassum angustifolium on growth and survival of shrimp Litopenaeus vannamei juvenile was investigated under challenge with shrimp pathogen bacteria Vibrio harveyi. Powder form of the extract was bioencapsulated in Artemia and fed to L. vannamei juvenile reared as 5 groups inclouding C- (unenriched Artemia, without bacteria), C+ (unenriched Artemia, with bacteria), T1 (enriched Artemia with 200 mg l-1 SA extract, with bacteria), T2 (enriched Artemia with 400 mg l-1 SA extract, with bacteria), T3 (enriched Artemia with 600 mg l-1 SA extract, with bacteria). One week after culture all groups except C- were inoculated with V. harveyi at the rate of 1.5 × 108 CFU ml-1 for 15 minutes then after every water exchange 10 ml of V. harveyi at the rate of 1.5 × 107 CFU ml-1 was added to aquaria. Shrimps at group C- showed maximum survival (86.6%), specific growth rate (SGR, 11.33%) and less bacterial load (0.5 ± 0.03× 102 CFU g-1 tissue). While (C2) exhibited lowest survival (33.3%), SGR (9.90%) and more bacterial load (3.4 ± 0.05× 105 CFU g-1 tissue) and the difference was significant (p<0.05). In treatment groups survival and SGR were significantly (p<0.05) more than C+ and less than C-, also bacterial load were less than C+ and more than C-. Among treatment groups T2 that fed with enriched artemia with 400 mg l-1 SA extract gave better results.