Salmon farming is a flourishing aquaculture industry throughout the world and
relies on intensive husbandry practices and well balanced diets to succeed. As in
agriculture, genetics, health, husbandry, and nutrition are the main pillars of a
successful and sustainable industry. Astaxanthin, a xanthophyll pigment with
antioxidant properties, is incorporated into farmed salmon diets to provide the desirable
red colour in flesh. Dietary antioxidant supplements (i.e. vitamins, flavonoids) have been
shown to fight free radicals normally formed during aerobic metabolism and generated
in excess during some physiological and pathological processes (i.e. exercise, disease).
This research was conducted to investigate the role of dietary supplementation,
with grape seed extract and astaxanthin, on pigmentation, growth and the immune
response, of pre-smolt and post-smolt chinook salmon spp maintained in freshwater
(FW) and saltwater (SW). Four experimental diets were formulated that contained
uniform amounts of astaxanthin (60 ppm) and one of two concentrations (low and high)
of grape seed extract (Kikkoman Proanthocyanidins, KPA®). The control diet (no
astaxanthin, no KPA®), astaxanthin diet (astaxanthin, no KPA®), low KPA® diet
(astaxanthin, 100 ppm KPA®), and high KPA® diet (astaxanthin, 1000 ppm KPA®) were
fed for 32 days to pre-smolt chinook salmon in FW tanks, and 155 days to post-smolt
chinook salmon in SW growout seacages.
Pre-smolts fed fortified diets with the antioxidants KPA® and astaxanthin, showed
a significantly (p=0.043) larger weight gain than fish groups fed the control diet after 32
days. There were no significant weight differences among the groups ingesting the
antioxidant-fortified diets. The specific growth rates (SGR) and feed conversion ratios
(FCR) were not significantly different between groups fed the four experimental diets in
FW. Conversely, muscle astaxanthin concentrations were significantly higher (p=0.019)
in groups fed the astaxanthin-containing diets compared to baseline values and fish fed
the control diet. There were no significant differences either in the concentration of
astaxanthin in fish muscle or on the apparent astaxanthin retention coefficients (AARC)
in salmon fed either the astaxanthin, low or high KPA® diets.
After a feeding period of 155 days in SW, post-smolts fed the high KPA® diet had
a significantly higher deposition of astaxanthin in muscle (p=0.036), higher visual colour score in fillets as measured by the Roche Salmofan® (p=0.029), and greater wet weight
gain (p<0.001) than those fed the other three diets.
Following a disease challenge with Vibrio anguillarum, pre-smolts fed the high
KPA® diet had a significantly lower (p=0.038) cumulative mortality among diet
treatments, as well as a significantly greater (p=0.025) number of circulating leucocytes
(p=0.025), neutrophils (p=0.018), and monocytes (p=0.034). Furthermore, the lysozyme
activity both in plasma and head kidney, and the neutrophil respiratory burst activity
were significantly greater in fish fed the high KPA® diet, (p=0.029, p=0.037, and
p=0.027, respectively).
It is concluded that the addition of antioxidants (proanthocyanidins and
astaxanthin) to a chinook salmon diet significantly enhanced the humoral and cellular
non-specific immune response factors and was related to a lower cumulative mortality
after the disease challenge. Furthermore, the deposition efficiency of the carotenoid
astaxanthin, and growth-related variables in farmed chinook salmon were also
significantly affected by the combination of dietary antioxidants.
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:BVAU.2429/15076 |
| Date | 05 1900 |
| Creators | Schlicht, Alberto |
| Source Sets | Library and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada |
| Language | English |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Relation | UBC Retrospective Theses Digitization Project [http://www.library.ubc.ca/archives/retro_theses/] |
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