Effect of prolonged fasting on lipid and fatty acid composition in rainbow trout, Salmo gairdneri

1981

Leger, C.

Young rainbow trout (mean weight: 40 g) were starved for 36 days. The water temperature ranged from 10 to 12 deg C. The results were compared with those of the control animals. Trout weight loss was 5 g/day/kg, i.e. 18 and 34% of initial wet weight and dry weight, respectively. The total lipid (LT) loss was 0.89 g/day/kg, i.e. 71% of the initial amounts of LT. The proportions of lipid loss as compared to total wet and dry weight loss were 18 and 37%, respectively. During starvation, the loss of nonlipid components was 1.6 times higher than the loss of lipid components. The starved trout almost exclusively used neutral lipids (LN:94%) as lipid fuel. Thus, the phospholipids (LP) represented a negligible energy source. Conversely, an appreciable proportion (8.5%) of initial phospholipids was consumed during starvation. It seems that long-term fasting weight loss involves a breakdown of the membranes as soon as the lipid depots reach values as low as 2% of wet weight. The fatty acid composition of phospholipids and neutral lipids was markedly constant, whereas the level of neutral lipids, as compared to the controls, was reduced 83% during starvation. Thus, the trout cannot specifically metabolize polyunsaturated fatty acid as suggested by some authors. On the contrary, the palmitic acid of neutral lipids was selectively utilized, but this preferential utilization was not very important quantitatively. The unsaturated fatty acids 16:1 n-7 and 20:5 n-3 of neutral lipids decreased, whereas the level of 20:1 n-9 increased. Factors explaining the decrease of 20:5 n-3 have been suggested

[Aquaculture (Netherlands)]

1982/XE/XE1982_0.rdf