Abstract
This study aimed to evaluate the effects of including microalgae Chlorella sp. or Nannochloropsis sp. in plant-based diets on antioxidant mechanisms of European sea bass (Dicentrarchus labrax) juveniles. For this purpose, three isoproteic (50%) and isolipidic (19%) diets were formulated: a practical diet, containing 15% fish meal (FM) and plant ingredients as the protein source and a mixture of fish oil and vegetable oils (40: 60) as lipid source (control diet); and two diets identical to the control but with the FM replaced by Nannochloropsis sp. or Chlorella sp. (diets Nanno and Chlo, respectively). The diets were offered to quadruplicate groups of 25 fish (initial body weight: 24 ± 1 g) for 11 weeks and then enzymatic and non-enzymatic antioxidant mechanisms and lipid oxidative biomarkers were assessed in the liver and intestine of these fish. Results showed that the antioxidant response was tissue-dependent, with the liver exhibiting lower glutathione peroxidase and glucose-6-phosphate dehydrogenase (only in Chlo group) activities, and intestine lower superoxide dismutase activity with the diets including microalgae compared to control diet. An increase of oxidized glutathione content was also observed in the intestine of fish fed the microalgae diets. Catalase and glutathione reductase activities, oxidative stress index, and total and reduced glutathione, were unaffected by dietary treatments in both tissues. Overall, the lipid peroxidation status was not compromised by the replacement of FM by microalgae.
Highlights
Finding sustainable ingredients alternative to the finite world fisheries products remains a major issue for the sustained growth of aquaculture [1]
Proximate composition was similar among diets; the dietary fatty acid profile was slightly different, with the microalgae diets having a higher n−6 polyunsaturated fatty acid (PUFA) content and an n−6/n−3 ratio than the control (Table 2)
lipid peroxidation (LPO) was shown to be a sensitive biomarker of increased oxidative stress as it is a major result of oxidative damage induced by different types of stressors, including nutritional factors [35]
Summary
Finding sustainable ingredients alternative to the finite world fisheries products remains a major issue for the sustained growth of aquaculture [1]. High or total replacement of fish meal (FM) by PF without affecting growth performance has been successfully achieved in carnivorous species, Microalgae Impact on Fish Oxidative-Status the presence of antinutritional factors (protease inhibitors, lectins, saponins, phytic acid, non-starch polysaccharides, among others) in most PF has been related to adverse effects on fish nutrient digestion and utilization, liver and intestine histomorphology, immune, and inflammatory responses [3,4,5,6] Overall, this may affect target functions in the body, including increased fish susceptibility to oxidative stress. Animals developed a complex antioxidant protection system that involves antioxidant enzymes (superoxide dismutase, SOD; catalase, CAT; glutathione peroxidase, GPX; glutathione reductase, GR) and non-enzymatic antioxidants (Coenzyme Q10, glutathione, ascorbic acid, uric acid, lipoic acid, bilirubin, etc.) [7]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
