Different potential immunostimulants were investigated to detect changes in the activity of non-specific defense mechanisms in sturgeon hybrid, Acipenser ruthenus × A. baerii. In the experiments, fish were fed with glucan, vitamin U, and vitamin C to show the effects of immunostimulation. Fish were fed diets containing two doses of glucan (0.1 and 0.5%) for 8 weeks, three doses of vitamin U (100, 200 and 300 p.p.m) for 4 weeks, and different doses of L-ascorbic acid (AA) (10; 100 and 1,000 mg/kg) for 20 weeks. Oral application of glucan enhanced leukocyte activity within 2 weeks after feeding 0.5% glucan/food kg. Production of oxidative radicals, as detected by the nitrobluetetrazolium (NBT) assay, rose after treatments. An elevated phagocytosis was observed only in the group fed with a higher dose of glucan. After 4 weeks of feeding with vitamin U, even the lowest dose of vitamin U (100 p.p.m.) significantly increased phagocytosis and respiratory burst activity of circulating leukocytes. Fish fed with vitamin C had significantly lower erythrocyte and leukocyte counts compared with the control group, but the volume of the erythrocytes as measured by the mean corpuscular volume (MCV) and the mean hemoglobin concentration (MCH) were lowest in the control group. This indicates anemia related to iron deficiency. Plasma lysozyme activity in fish fed 100 and 1000 mg AA was remarkably high, while no other differences were found among the various groups.
ASJC Scopus subject areas
- Aquatic Science