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Replacement of marine products with alternative proteins and oils in feeds for Atlantic salmon (Salmo salar L.) : effect on growth, immune function and disease resistance

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Bransden, Matthew Paul (2001) Replacement of marine products with alternative proteins and oils in feeds for Atlantic salmon (Salmo salar L.) : effect on growth, immune function and disease resistance. PhD thesis, University of Tasmania.

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Abstract

Replacement of marine proteins and oils in feeds for carnivorous fishes such
as salmonids has been identified as a key research area. Alternative proteins
and oils from vegetable and terrestrial-animal sources can effectively replace
marine products, although often growth is the only criteria used to assess their
potential. On few occasions has the health of the animal been considered. This
research aimed to evaluate what effect alternative protein and oil sources had
on growth, immune function and disease resistance when fed to Atlantic
salmon, Salmo salar L., parr.
Locally available proteins from vegetable and terrestrial-animal sources were
initially 'screened' by feeding to salmon to determine any deleterious effects
on blood chemistry or immune function. While no significant differences (P>
0.05) were observed, data suggested certain proteins stimulate
immunoglobulin production compared to fish meal-fed controls. In a short
term experiment, four of these proteins (corn gluten, dehulled lupin, feather
meal and poultry meal) were fed to salmon that had been acclimating on a fish
meal-based control feed, although the change in protein source did not
significantly affect feed consumption or immune function. Growth of salmon
fed dehulled lupin, a mixture of dehulled lupin and feather meal, or fish meal
were not significantly different in a longer term study, although salmon fed
feather meal were found to have significantly reduced (P < 0.05) growth
compared to those fed fish meal. Further, no significant differences were
recorded in immune function or resistance to Vibrio anguillarum infection.
Lysine is usually the first limiting amino acid when alternative protein sources
are used in salmon feeds, although the immune response of salmon fed a range
of lysine concentrations below or above known requirement was not
significantly altered.
Three feeds containing canola oil, a mixture of canola and fish oil, or a
mixture of canola oil and a marine microheterotroph (Thraustochytrid) meal,
did not affect salmon blood chemistry or immune function. Salmon fed the
combination of canola and fish oils however had significantly lower (P <
0.05) cumulative mortality after V. anguillarum challenge compared to the
remaining feeds. Finally, sunflower oil was used to gradually replace fish oil
to alter the dietary omega-3: omega-6 (n-3/n-6) ratio. Although growth and
immune function did not differ between feeds, significant differences in
cumulative mortality were recorded after challenge with V. anguillarum but
they were not correlated to dietary n-3/n-6 ratio.
Experiments generally demonstrated alternative protein and oil sources could
be used in Atlantic salmon feeds without affecting growth, blood chemistry or
immune function. Disease resistance however was shown to be altered when
dietary oil or n-3/n-6 ratio was changed, although exact mechanisms for these
differences are unclear, and warrant further study.

Item Type: Thesis (PhD)
Keywords: Atlantic salmon
Copyright Holders: The Author
Additional Information:

Thesis (Ph.D)--University of Tasmania, 2001. Includes bibliographical references

Date Deposited: 25 Nov 2014 00:50
Last Modified: 11 Mar 2016 05:54
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