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Dietary oil modulates fatty acid profile in disease challenged barramundi


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Alhazzaa, R, Bridle, AR, Nichols, PD and Carter, CG 2011 , 'Dietary oil modulates fatty acid profile in disease challenged barramundi', paper presented at the Aquaculture America 2011, 28 February - 3 March 2011, New Orleans, U.S.A..

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There are interactions between fish lipid profile and their health and physiology. Fatty
acids (FA) are required for normal growth and development and are important in
immunity modulation and disease resistance. The n-3 and n-6 long-chain polyunsaturated
fatty acids (LC-PUFA) affect immune response partly by affecting cytokine secretion and
pro-inflammatory factors. Using plant oils, such as Echium plantagineum oil (EO),
instead of fish oil (FO) in barramundi feed formulations may be useful as EO has
potential to provide a precursor for synthesis of LC-PUFA. However, the immune system
could be impaired as a result of changing the FA profile of fish fed on alternate oils. We
therefore investigated the changes of FA depots in disease challenged barramundi fed on
EO instead of FO on bacterial infection. Worldwide, bacterial infection with
Streptococcus iniae is responsible for significant mortalities of warm water aquaculture
species including barramundi. Fingerlings (50±2g) were kept at 30°C, 15 ppt salinity, 24
h light photoperiod and fed one of three dietary treatments differing only in their lipid
source: FO, EO and canola oil (CO). Following 5 weeks, fish were challenged with S.
iniae (1-2×105 cfu/ml bathing exposure) causing sub-acute infection. FA profiles in
muscle were compared in initial fish and after one week of challenging when fish showed
signs of recovery. Feed intake dropped initially in infected fish and was paired with the
control group which remained intact. Similar growth ratios were observed in all dietary
treatments during the experiment as well as equal mortality rates following the bacterial
infection, with EO-fed fish retaining SFA, MUFA, n-3 and n-6 PUFA depots better than
FO and CO. When compared with the control group, fish fed alternatives to FO showed a
comparable ratio of utilising n-3 and n-6 LC-PUFA depots while challenged and
sustained the n-3: n-6 ratio through the infection period. These findings indicate efficient
growth, survival and lipid metabolism in barramundi fed on plant oils as alternatives to
FO with capacity to sustain flesh quality in unfavorable production conditions such as
when bacterial infection occurs.

Item Type: Conference or Workshop Item (Paper)
Authors/Creators:Alhazzaa, R and Bridle, AR and Nichols, PD and Carter, CG
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