Fatty acid profile in rainbow trout (Oncorhynchus mykiss) as influenced by diet

Abstract

With the aim of reinforcement S&T capacities in aquaculture, studies on the influence of three commercial pelleted diets on fatty acid profile in rainbow trout production were undertaken. Commercial diets for rainbow trout contained significantly different quantities of saturated fatty acids (SFA), (p<0.05), ranging from 21.02 to 38.50%. Significant differences between diets (p<0.05) were established in the proportions of monounsaturated fatty acids (MUFA), (29.56- 45.21%) and polyunsaturated fatty acids (PUFA), (31.95 to 36.43%). The established quantities of EPA (C20:5 n-3) and DHA (C22:6 n-3) in diets were 8.69, 9.11, 11.36% and 3.90, 5.30, 8.18%, respectively. The share of n-3 and n-6 fatty acids (FA) ranged from 17.97 to 26.33% and from 10.10 to 13.98%, respectively. The n-3/n-6 ratio was in the range 1.29-2.61. The major SFA (total SFA: 22.17- 35.63%) in fish samples was palmitic acid (C16:0), (15.61-24.65%). Oleic acid (C18:1cis-9) was the most abundant from the MUFA family (21.90-31.89%), (total MUFA: 35.00-43.50%). From PUFA family (total PUFA: 29.38-34.33%), linoleic acid (C18:2 n-6), (10.09-10.97%), EPA (2.95-4.26%) and DHA (7.53-10.39%) were present in significant quantities in trout. Quantities of n-3 FA ranged from 17.08 to 21.12% and significant differences (p<0.05) were established between trout fed Diet I and Diet III. The proportion of n-6 FA ranged from 12.29 to 13.21% and no significant differences were established (p>0.05). The n-3/n-6 ratio ranged from 1.39 to 1.60 and differences were not statistically significant (p>0.05). The obtained results indicate that fatty acid profile of fish reflects the fatty acid composition of fish diets, with some variabilities which indicate that the incorporation of fatty acids in fish tissue is under some metabolic effects.