Dietary administration of Sargassum angustifolium and Gracilaria pulvinata extracts affect antioxidant enzyme activities and Lactobacillus bacterial population in intestine of rainbow trout (Oncorhynchus mykiss) fry

Document Type : Research Paper


1 Department of Fisheries, Faculty of Agriculture and Natural Resources, Persian Gulf University, Bushehr, Iran

2 2Lorestan Fisheries Adminestration, Khoramabad, Iran

3 Department of Animal Husbandry, Faculty of Agriculture and Natural Resources, Persian Gulf University, Bushehr, Iran


This study investigated the effect of Sargassum angustifolium and Gracilaria pulvinata extracts on the growth performance, body composition, antioxidant status and gut microbiota of rainbow trout (Oncorhynchus mykiss)fry. For this purpose, 540 fry of rainbow trout (initial weight 0.23±0.04g) were distributed in 12 fiberglass tanks. Fish were fed with experimental diets, containing 500mg kg-1 of Sargassum extract (SA), 500mg kg-1of Gracilaria extract (GL) and 250mg kg- Sargassum+250mg kg-1 Gracilaria extract (SA+GL). The control diet was a commercial diet without seaweed extract. At the end of the experiment growth and feeding performance, including final weight, specific growth rate (SGR), weight gain (WG) and feed conversion (FCR) in all treatments were not significantly different (p >0.05). Whole body protein, ash and moisture contents of fish were not significantly affected by dietary macroalgae extracts (p >0.05). However, lipid content was significantly lower in fish fed with extract og Gracilaria and Sargassum compared to control (p <0.05). The seaweed extract-fed fish utilized efficiently the body lipid and suppressed weight loss of the body during starvation. No significant difference (p >0.05) in serum total protein, creatinine alanine transaminase (ALT), aspartate aminotransferase (AST), alkaline phosphatase (ALP) and blood superoxide dismutase (SOD) activity was observed in all treatments. Whereas serum albumin, glutathione peroxidase (GPX) and catalase specific activity were higher in SA, GL and SA+GL treatments compared to the control group (p <0.05). ACH50 level was significantly (p <0.05) increased in GL and SA+GL treatments as compared to SA and control group. The addition of Sargassum and Gracilaria extracts to feed did not affect total bacterial population but increased Lactobacillus bacteria levels (p <0.05) in the intestine. These results revealed potential antioxidant enhancing and health-promoting effects of dietary Sargassum angustifoliumand Gracilaria pulvinata extracts.