Effect of high levels of dietary vitamin C on the blood responses of matrinxã (Brycon amazonicus).

Juvenile matrinxã (Brycon amazonicus) were fed with different dietary vitamin C (ascorbic acid or AA) concentrations for 2 months in order to evaluate its effect on the physiological condition of this species. Five treatments were tested: Reference diet-RD (350 mg AA kg(-1) and 45% crude protein commercial feed); C400, C500, C600 and C800 with supplementation of 400, 500, 600 and 800 mg AA kg(-1). Fish fed 800 mg AA kg(-1) supplemented diets presented greater weight gain and survival. Hematocrit, hemoglobin concentrations and erythrocytes showed significant increase (p<0.05) in C600 and C800 relatively to the others. Total leukocyte values were significantly higher in fish fed vitamin C supplemented diets relatively to those fed RD and leukocytes count of C600 and C800 were the highest among the treatments. Monocytes were the only cells of fish defense mechanism that presented variation, and C600 and C800 presented the lowest values (P<0.05). Glucose level was significantly different relatively to RD only in C400 and the plasmatic total protein values for fish fed vitamin C supplemented diets were higher than for fish fed the RD. Fish plasmatic ions (Na(+) and Cl(-)) were significantly lower for C500, C600 and C800 relatively to C400 and RD. The physiological profile and the growth performance of matrinxã suggest that diet supplemented with 800 mg AA kg(-1) can improve its performance and increase the survival rate.

Influence of diets supplemented with vitamins C and E on pirarucu (Arapaima gigas) blood parameters.

This study evaluated the influence of diets supplemented with 500, 800, 1200 mg kg-1 of vitamin C (ascorbic acid or AA) and vitamin E (alpha-tocopherol or alpha-T) on the physiological responses of pirarucu fed for 2 months. Weight and mortality were not affected by dietary vitamin type or their concentrations. Significant increase (p<0.05) on the red blood cells count was obtained on treatments with 800 and 1200 mg AA kg-1 and on the hemoglobin concentration on treatment with 500 mg alpha-T kg-1 relatively to control. Mean corpuscular volume presented a significant decrease (p<0.05) on treatment with 800 and 1200 mg AA kg-1 when compared to control. Mean corpuscular hemoglobin concentration was significantly high (p<0.05) on treatment with 500 mg alpha-T kg-1. Only in vitamin C treatments, we noticed a significant increase (p<0.05) in the number of leucocytes relative to control. All fish in the vitamin-supplemented treatments, except 500 mg AA kg-1, had high total protein values compared to control. Fish treated with 800 or 1200 mg alpha-T kg-1 also showed increases in plasma glucose concentrations. Our results suggest that 800 and 1200 mg AA kg-1 are probably the most suitable concentrations for pirarucu diets, although high vitamin E diets are not necessary for quantitative leucocyte increases for this species.

The influence of dietary vitamin C and E supplementation on the physiological response of pirarucu, Arapaima gigas, in net culture.

This study evaluated the efficacy of dietary vitamin C (ascorbic acid or AA), vitamin E (alpha-tocopherol or alpha-T), and C+E supplementation on the blood parameters of Arapaima gigas grown in net cages for 45 days. Four treatments were tested: control (commercial feed); C800; E500 and C+E (800+500) with supplementation of 800 mg AA kg(-1), 500 mg alpha-T kg(-1) and 800+500 mg AA+alpha-T kg(-1), respectively. Hematocrit (Ht), red blood cells (RBC), and hemoglobin concentration (Hb) (oxidative status indicators), thrombocytes and leukocytes (immunological indicators), plasma protein and glucose were evaluated. Fish fed vitamin C and C+E supplemented diets showed greater weight gain and survival. Dietary vitamin C and C+E diet supplementation resulted in increased Ht, Hb, RBC, MCHC, total leukocytes, total proteins, thrombocytes and eosinophils compared to the control and alpha-T. The alpha-tocopherol-supplemented diet reduced the number of total thrombocytes, lymphocytes and neutrophils and increased glucose and eosinophils relatively to the control. In general, leukocytes and thrombocytes were good indicators of the efficiency of vitamin on the defense mechanism of the A. gigas reared in cages. Results indicate that high alpha-T diet supplementation provides no benefit for the maintenance of the oxidative or the immunological status of A. gigas. However, it was demonstrated that high dietary AA improves A. gigas immunological status. Red blood cell indices and immune system indicators showed no synergistic effect between the vitamins after supplementing the A. gigas diet with alpha-T+AA.