Growth performance, antioxidant activities, and immunological responses of hapa-reared thinlip mullet (Liza ramada) juveniles fed on diets supplemented with spirulina (Arthrospiraplatensis).

Spirulina (Arthrospira platensis) (SP) has been utilized for a long time as a valued feed supplement because of its proteinous content and other beneficial phytochemical compounds. Herein, we investigated the influences of SP-supplemented diets on growth, body somatic indices, digestive enzymes, hepatic antioxidant activities, and immunological responses of hapa-reared thinlip mullet (Liza ramada) juveniles. Fish were assigned in six triplicate groups and were fed for consecutive 60 days on the prepared experimental diets containing varying SP levels as 0.0, 2.0, 4.0, 6.0, 8.0, and 10.0 g/kg diet and defined as control (CNT or SP0), SP2, SP4, SP6, SP8, and SP10 groups, respectively. The results indicated that dietary SP supplementation linearly and quadratically improved the fish growth performance, and the highest growth indices were found in the SP8 group. However, dietary SP supplementation did not significantly alter feed conversion ratio (FCR), survival rate (%), hepato-somatic index, and viscera-somatic index among all experimental groups. Meanwhile, digestive enzymes (lipase, α-amylase, and proteases) in the mid-intestine were also linearly and quadratically increased in all SP-fed groups, and their uppermost values were noted in the SP8 group. Hepatic antioxidants such as superoxide dismutase, catalase, and total antioxidant capacity in SP-supplemented groups were significantly elevated than the CNT group. Conversely, hepatic malondialdehyde contents were decreased significantly along with increasing dietary SP-supplementation levels. The immunological parameters such as lysozyme, respiratory burst, and alternative complement activities were significantly elevated in SP-fed groups than in the CNT group. These findings evoked that feeding SP-supplemented diets (especially at 8.0 g/kg diet) significantly promoted the growth, digestive enzymes, hepatic antioxidant status, and immunity of L. ramada juveniles.

Dietary supplementation of organic selenium improves growth, survival, antioxidant and immune status of meagre, Argyrosomus regius, juveniles.

Oxidative stress is considered one of the main obstacles to immune competence and high mortality rate of marine fish larvae due to the high dietary polyunsaturated fatty acids and accelerated metabolic rate. This study was carried out to assess the effect of different dietary selenium (Se) yeast on growth, antioxidant status, hematological changes, and cellular and humoral immune parameters in meagre (Argyrosomus regius). Juvenile specimens (3.20 ± 0.17 g) were randomly assigned to four experimental groups, a control group fed a basal diet and another three groups fed Se-supplemented diets at doses of 1, 2 and 3 mg Se-yeast kg-1 diet for 63 days and the final analyzed selenium concentrations were 0.77, 1.51, 2.97 and 3.98 mg Se kg-1 diet, respectively. The results indicated that growth performance, feed conversion ratio and survival were significantly improved with 2.97 and 3.98 mg Se-yeast kg-1 compared to the control group. The catalase, superoxide dismutase activities and total antioxidant status were significantly increased, and thiobarbituric reactive substances in liver homogenate were significantly decreased with increasing Se supplementation respect to the control fish in a dose-dependent manner. Furthermore, hematological and innate immune parameters (immunoglobulin, lysozyme, myeloperoxidase, ACH50 and respiratory burst activity) were also significantly higher in fish fed the Se-yeast supplemented diets compared to the control group. The results demonstrated that the supplementation of 3.98 mg Se-yeast kg-1 diet improves growth performance, antioxidant balance and innate immune status of meagre juveniles.