Effect of diet on the lipid composition of wild and cultured abalone

Abstract

Foot-muscle tissue from wild-caught adults of the two main commercial species of Australian abalone, Haliotis laevigata and H. rubra, were analysed for fatty acid and sterol composition. Foot muscle tissue from juvenile H. laevigata and hybrid H. laevigata X H. rubra fed an artificial diet was compared with that of juvenile H. laevigata fed the green alga Ulva australis. The major fatty acids in all samples of muscle were 16:0, 18:0, 18:1(n-9), 18:1(n-7), 20:4(n-6), 20:5(n-3) and 22:5(n-3). The abundance of 22:5(n-3) is unusual as most marine animals have much more 22:6(n-3). The muscle of juvenile abalone fed an artificial diet high in total lipids and 18:2(n-6) contained elevated total lipid levels and elevated levels of 18:2(n-6) and 20:2(n-6). The muscle of abalone fed U. australis, which was high in C 16 and C 18(n-3) polyunsaturated fatty acids (PUFA), contained elevated proportions of their chain-elongation products C 20 and C 22(n-3) PUFA, which is similar to wild-caught adult abalone. The major sterol in all samples of abalone muscle was cholesterol, irrespective of diet. The muscle of juvenile H. laevigata fed an artificial diet high in 24-methylcholest-5-enol and 24-ethylcholest-5-enol contained elevated proportions of these sterols compared with the muscle of juveniles fed U. australis and wild-caught adult abalone. Observed differences in fatty acid and sterol compositions were attributed to the accumulation of lipid in the foot muscle of abalone fed an artificial diet.