do conjugated linoleic acid (cla) in diets for atlantic
salmon (salmo salar) juveniles affect fatty acid metabolism and bone
mineralisation?
G.M.
Berge, B. Ruyter, T. Asgard
Triplicate
groups of 0.7 g Atlantic samon (Salmo salar) fry were offered diets
containing 0, 0.5, 1.0 or 2.0%CLA for 3 subsequent periods of 28 days. Fish
were weighed in bulk, and samples for proximate, fatty acid and mineral
analyses were collected at start, and after each 28-day period. Growth rates
were calculated, as well as fatty acid content in body burden increase (BBI)
of lipid and deposition ratio (RD) of fatty acids. No significant
effect of CLA on growth rate or proximate composition was observed. Fatty
acid composition was strongly affected by diet. CLA was deposited in the
fish, but dietary CLA also affected the deposition of other fatty acids.
Increased RD of C14:0, C16:0 and C18:0, and decreased RD
of C16:1 and C18:1, in response to increasing levels of CLA in the diets,
indicated that CLA may cause a reduction in delta-9 desaturase activity.
Dietary CLA caused a significant increase in R D of total n-3
fatty acids, especially of C22:6n-3. CLA also caused a higher concentration
of phosphorus (P) and calcium (Ca) and a lower P:Ca ratio in fish. The
results indicate that dietary CLA may affect fatty acid metabolism and bone
mineralization.
(AKVAFORSK,
Institute of Aquaculture Research, N-6600 Sunndalsora, Norway, e-mail of T.
Asgard: torbjorn.asgard@akvaforsk.nlh.no)