Fish Oil Replacement by a Blend of Vegetable Oils in Diets for Juvenile Tench (Tinca tinca Linnaeus, 1758): Effects on Growth Performance and Whole-Body Composition

Abstract

Among freshwater species, tench (Tinca tinca Linnaeus, 1758) is considered as a promising species for the diversification of aquaculture, but the intensification of techniques is necessary to promote and consolidate its culture. Adequate feeding in early growth phases is essential to face further grow-out. Fish oil (FO) is the main source of lipids in fish diets, but its production is unsustainable, and thus, alternative oils should be considered. A 90-day experiment was performed to evaluate the effects of partial and total replacement of cod liver oil (FO) by a blend of vegetable oils (VO) in juvenile tench. Six isonitrogenous and isolipidic diets with different levels of a VO blend containing 30% linseed oil, 20% corn oil, and 50% olive oil were tested: 0% (control), 20%VO, 40%VO, 60%VO, 80%VO, and 100%VO. With all diets, survival was 100%, and there were not differences in growth performance (total length (TL); weight (W); specific growth rate (SGR); feed conversion ratio (FCR); and biomass gain (BG)). Compared to the control group, whole-body lipid content decreased significantly in the 100%VO group. No differences in total saturated (SFA), monounsaturated (MUFA), and polyunsaturated (PUFA) fatty acids were found in the whole-body. The content of linolenic acid (ALA) in the whole-body increased as FO substitution did, being significantly higher with respect to control diet from 40% FO replacement diets. Nutritional indices, such as ΣPUFA/ΣSFA and Σn-6/Σn-3 ratios, tended to increase with increasing VO content, whereas the EPA + DHA showed an opposite trend. A total replacement of FO by the blend of VO did not affect the growth performance and fatty acid profile of juvenile tench. Further research on the effects of VO diet on nutritional quality in tench reared to commercial size should be performed.

Fish Oil Replacement by Camelina (Camelina sativa L.) Oil in Diets for Juvenile Tench (Tinca tinca L.): Effects on Survival, Growth, and Whole-Body Fatty Acid Profile

“…In this experiment, this ratio varied between 0.75 and 0.92, corresponding to the control diet and 100% CO diet, respectively. These values were similar to those obtained by Sáez-Royuela et al [ 36 ] in juvenile tench fed diets with different substitutions levels of FO with a blend of vegetable oils. Linhartovà et al [ 49 ] reported higher values in the flesh of commercial-sized tench either under extensive culture (average weight 210 g, ΣPUFA/ΣSFA: 1.32) or semi-intensive conditions (average weight 680 g, ΣPUFA/ΣSFA: 1.10).…”

“…In the same way, Mzengereza et al [ 29 ] and Maldonado-Othón et al [ 19 ] reported a decrease in lipid content in muscle when camelina oil was included in the diet. In studies with juvenile golden pompano ( Trachinotus ovatus ) and juvenile tench, Guo et al [ 44 ] and Sáez-Royuela et al [ 36 ], respectively, found an association between body lipid content and dietary ALA/LA so that the lowest body lipid content coincided with the highest ALA/LA ratio. In our experiment, the same relationship was found, and the high lipid deposition corresponded to juveniles fed the control diet (ALA/LA = 0.25) whereas juveniles fed 100% CO (ALA/LA = 1.14) had lower lipid whole-body content.…”

“…Later, Sáez-Royuela et al [ 35 ] determined that an 8.5% dietary lipid content (2% of cod liver oil) should be present in the formulation. Recently, a study on the possibilities of FO replacement by a blend of VO (linseed oil, corn oil, and olive oil) showed that total substitution was feasible without negative effects on growth performance or whole-body composition [ 36 ]. Considering that camelina is an alternative oilseed crop with a markedly low environmental impact and its oil has a high unsaturated fatty acid content, the present work aimed to know the effects of partial or total replacement of FO with CO on the survival rate, growth performance, and whole-body composition of juvenile tench.…”

Modification ω-6/ω-3 ratio and increase of the shelf life of anchovy oil (Engraulis ringens) with addition of olive oil (Olea europaea)

“…However, in the aquaculture sector where up to 75% of the world's fish oil is used, leveraging the price of fish oil by partial substitution of vegetable oils could show economic incentives in the future. Therefore, studies have already been carried out in this line of research, finding that the substitution of fish oil with vegetable oils, including olive oil, does not significantly affect the nutritional strengths and impact on fish growth (Nasopoulou and Zabetakis, 2012;Sáez-Royuela et al, 2022). On the other hand, although global fish oil production is expected to increase until 2027 (Chouhan et al, 2020), recent studies indicate that global warming is causing substantial decreases of essential fatty acid v-3 in plankton, especially eicosapentaenoic acid (EPA), which would represent a loss of quality in fish feed and therefore in the nutritional quality of fish (Holm et al, 2022).…”