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

D Trbovic,J Djinovic-Stojanovic,D Spiric,V Matekalo-Sverak,V Djordjevic,A Spiric,D Vranic,J Babic,R Petronijevic

doi:10.2298/bah1203563t

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.

Highlights

Uncontrolled and long term exploitation of sea resources as well as knowledge on the favorable impact of n-3 polyunsaturated fatty acids (PUFA) on human health, contributed to considerable investments in aquaculture all over the world (Williams, 1998)
Some fish species from inland aquaculture are more capable than marine fish to desaturate and elongate C18 polyunsaturated fatty acids to valuable highly unsaturated fatty acids, EPA and DHA, even when their feed is less rich in these fatty acids (Tocher et al, 2004)
PUFAs were present in quantities of 33.73% (Diet I), 31.95% (Diet II) and 36.43% (Diet III)

Summary

Introduction

Uncontrolled and long term exploitation of sea resources as well as knowledge on the favorable impact of n-3 polyunsaturated fatty acids (PUFA) on human health, contributed to considerable investments in aquaculture all over the world (Williams, 1998). Proteins of high biological value, low fat content and relatively low cholesterol content, as well as valuable quantities of essential fatty acids makes fish one of the most appreciable food stuffs in human nutrition (Conor, 2000; Sidhu, 2003). Some fish species from inland aquaculture are more capable than marine fish to desaturate and elongate C18 polyunsaturated fatty acids to valuable highly unsaturated fatty acids, EPA (eicosapentaenoic acid) and DHA (docasahexaenoic acid), even when their feed is less rich in these fatty acids (Tocher et al, 2004). It has been proved that nutritional value of fish can vary due to species, diet, location, environmental conditions, age, etc (Petterson et al, 2009; Sicuro et al, 2010). In farmed trout, where environmental conditions are more constant throughout the year, development and fish growth as well as fatty acid profile is more affected by food supply (Almeida et al, 2011). Many literature data indicate to a strong connection between fish diet and fatty acid profile of fish. (Caballero et al, 2002; Valente et al, 2007) Under the same rearing conditions, feed reach in n3 PUFAs significantly increase the n-3/n-6 ratio in fish (Skalli and Robin, 2004)

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