This thesis describes a number of experiments designed to further our knowledge of the complex relationship that exists between nutrition and the immune system of fish, with a view to finding a practical means of improving disease resistance in farmed fish. In particular, vitamins are known to play an important role in vertebrate immune responses, and in the present study the practical value of vitamin C as an immunostimulant was investigated. A study was also made of the capacity of vitamin C to ameliorate stress-induced immunosuppression, and of the effect of stress on the demand for and distribution of vitamin C amongst various tissues of Atlantic salmon (Salmo salar L). Taken together, the results of these studies revealed no significant evidence for a fundamental role for vitamin C in regulating the stress response of salmon, and no significant evidence that high vitamin C diets have any value as immunostimulants in aquaculture. The practical value of diets containing high levels of vitamin A and carotenoids were also investigated. Whilst there was some evidence that vitamin A deficiency resulted in increased disease susceptibility, there was no evidence to suggest that feeding elevated levels of these compounds was immunostimulatory. Hence, the practical value of these compounds in promoting disease resistance in aquaculture also appears limited. The immunomodulatory effect of differential food acquisition by individual fish kept in different ration groups (i.e. as determined by management feeding strategy), and also within those ration groups (as determined by social interaction) was also investigated. The results obtained indicate that feeding very high ration levels may have deleterious consequences for disease resistance in salmonids, a finding which may have major implications for the aquaculture industry. Overall, the results presented in this thesis have served to eliminate several avenues of research which were popular at the time of its conception, and to suggest new approaches which may lead to real improvements in disease resistance of farmed fish in the future.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:593561 |
| Date | January 1993 |
| Creators | Thompson, Ian |
| Publisher | University of Aberdeen |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://digitool.abdn.ac.uk/R?func=search-advanced-go&find_code1=WSN&request1=AAIU059130 |
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