The US hybrid striped bass (Morone chrysops x M. saxatilis) industry has been
negatively impacted by infectious diseases because there are very few approved drugs
and vaccines. Therefore, a series of experiments was conducted to explore the potential
use of various dietary supplements including autolyzed brewers yeast, the commercial
prebiotic GroBiotic®, oligonucleotides and levamisole for improvement of hybrid
striped bass growth, immunity and resistance to disease caused by various pathogenic
bacteria.
In two trials with brewers yeast, fish fed diets supplemented with yeast at 2%
generally showed enhanced weight gain and feed efficiency compared with those fed a
basal diet. Brewers yeast also positively influenced resistance to S. iniae infection. In
addition, results of immune response assays demonstrated that brewers yeast can be
administered for relatively long periods without causing immunosuppression.
GroBiotic® (Grobiotic) also resulted in significantly enhanced weight
gain, innate immune responses and resistance of juvenile hybrid striped bass to S. iniae
infection. An additional experiment with sub-adult fish showed significantly reduced
mortality of fish fed a diet supplemented with GroBiotic® at 2% when subjected to an in-situ Mycobacterium marinum challenge. This is the first report of positive effects from
dietary prebiotics for fish health management, although many fundamental questions
should be pursued further.
Dietary supplementation of a commercial oligonucleotide product (Ascogen P®)
at 0.5% of the diet was shown to enhance resistance of hybrid striped bass against S. iniae
infection and increased their neutrophil oxidative radical production. However, the effect
on growth was marginal.
Dietary levamisole supplementation at a low level (100 mg/kg) enhanced the
growth and feed efficiency of juvenile hybrid striped bass. However, an elevated dosage
(1000 mg/kg diet) strongly suppressed growth, feed intake and feed efficiency.
Hypothesized beneficial influences, including antibody production and resistance to S.
iniae and A. hydrophila were not substantiated. Although dietary levamisole increased
fish macrophage respiratory burst, an in vitro study failed to show a direct effect on
cultured macrophages.
This suite of studies demonstrated the potential use of some dietary supplements
to enhance hybrid striped bass production. Thus, immunonutrition represents a valuable
strategy to apply in aquaculture.
| Identifer | oai:union.ndltd.org:tamu.edu/oai:repository.tamu.edu:1969.1/3322 |
| Date | 12 April 2006 |
| Creators | Li, Peng |
| Contributors | Gatlin, Delbert M. |
| Publisher | Texas A&M University |
| Source Sets | Texas A and M University |
| Language | en_US |
| Detected Language | English |
| Type | Book, Thesis, Electronic Dissertation, text |
| Format | 1416629 bytes, electronic, application/pdf, born digital |
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