THE EFFECTS OF MARGINAL DEFICIENCIES OF ASCORBIC ACID AND ALPHA-TOCOPHEROL ON THE NATURAL RESISTENCE AND IMMUNE RESPONSE OF RAINBOW TROUT (SALMO GAIRDNERI)
Specific immunity and nonspecific resistence factors were studied in rainbow trout, Salmo gairdneri, marginally deficient in ascorbic acid and (alpha)-tocopherol. Commercially available diets may contain low levels of these vitamins due to their destruction during processing and storage. While low levels may not cause deficiency syndromes or death, increased susceptibility to infectious disease may result.^ Three laboratory prepared, casein based diets were used. A commercial trout pellet was fed for comparison purposes. The specific immune response to sheep red blood cells (SRBC) and to the salmonid pathogen Yersinia riclero were measured.^ Humoral immunity was assessed using the plaque-forming cell assay and serum agglutination. Migration inhibition factor and antigen-binding cell assays were used as measures of cellular immunity. The non-specific resistence factors measured were serum iron-binding capacity, total serum iron and the phagocytic index of peritoneal macrophages. In addition, total and differential blood cell counts, serum total protein and total globulin determinations were performed.^ (alpha)-Tocopherol deficiency depressed all aspects of humoral and cellular immunity as well as phagocytosis. It is hypothesized that (alpha)-tocopherol may have a generalized effect because of its importance to cell membranes.^ Ascorbic acid exhibited a more specific effect. The major consequence of a deficiency was a depression of non-specific resistence. A significant decrease in iron-binding capacity as well as phagocytosis was observed. The cellular response to Y. ruckeri was depressed, however no effect on the cellular response to SRBC was observed. This may indicate an effect on specific helper "T" cell populations.^ The fish fed commercial feed had a significantly decreased cellular response to SRBC, humoral response to Y. ruckeri and phagocytic ability. Since complete analysis of this diet was not available the exact mechanism of immune suppression could not be determined.^ A vitamin enhanced (three times the recommended levels of both vitamins) was fed for two weeks before vaccination with Y. ruckeri. A significantly enhanced humoral response was observed when compared to fish fed a commercial diet.^ This research indicates that fish fed commercial diets may be immunosuppressed and thus have increased disease susceptibility. Outbreaks of infectious disease occur most often at times of stress--spawning, handling and during periods of rapid temperature change. The possibility exists for immunopotentiation and increased resistence by vitamin supplementation before these times of stress. ^
Agriculture, Fisheries and Aquaculture|Health Sciences, Immunology
VICKI SUZETTE BLAZER,
"THE EFFECTS OF MARGINAL DEFICIENCIES OF ASCORBIC ACID AND ALPHA-TOCOPHEROL ON THE NATURAL RESISTENCE AND IMMUNE RESPONSE OF RAINBOW TROUT (SALMO GAIRDNERI)"
Dissertations and Master's Theses (Campus Access).