This study was carried out to investigate the effects of increasing levels of propolis addition as a feed additive in seabream (Sparus aurata) diets on the hematological parameters and the fish fatty acids profile. Seabream with an average weight of 12.04 ± 0.01 g were fed 0 (control), by 1.25, 2.5, 5, 10, 20 g/kg (abbreviated with P1.25; P2.5; P5; P10 and P20 respectively) propolis supplemented diets for 10 weeks. The experiment was conducted in three replications by adding 50 fish to 18 polyester tanks of 400 L. The trial groups were fed twice daily (09:00 and 17:00) by hand to satiation with feed containing 45% protein and 17% lipid. Although the propolis supplementation had no effect on seabream saturated fatty acids (SFA) and monounsaturated fatty acids (MUFA), the polyunsaturated fatty acid (PUFA) contents increased significantly after the addition of 10 g/kg propolis. Therefore, the addition of the propolis to feeds significantly affected the total fatty acid composition of fish (p <0.05). As a result, the propolis supplement improved the quality of seabream fatty acid composition. At the end of the experiment, hematological parameters such as RBC (erythrocyte count in red blood cells), HGB (hemoglobin count in blood) and HCT (erythrocyte and hemoglobin count in blood) in blood samples taken from fish were found to be higher in P20 group than the other groups. There was no significant difference between the experimental groups (p > 0.05). The addition of the propolis to their feed did not have any effect on the hematological parameters of seabream. The results obtained showed that the propolis has the potential to use in seabream feeds.
The present study evaluated fatty acid digestibility, histology, blood biochemistry and gene expression in the gut of juvenile gilthead sea bream, Sparus aurata (initial mean weight, 60.4 ± 4.9 g) fed with iso-proteic (48%) and iso-lipidic (20.7%) diets in which fish oil was partially (60%) or totally (100%) replaced with either camelina or chia oil. Each of the experimental diets was fed to triplicate groups of fish stocked at 10 fish/tank in 150 L tanks for 90 days. Although inclusion of camelina or chia oil altered dietary fatty acid (FA) profile, major differences in digestibility in the individual FAs were not observed. Total replacement of fish oil with camelina or chia oil did not have any effect on blood glucose levels, whereas cholesterol and triglyceride levels were reduced. Results of messenger ribonucleic acid (mRNA) transcription showed elevated levels in the expression of the elongases and desaturases in gilthead seabream fed with diets devoid of fish oil. Fish fed with camelina or chia oil based diets had increased expression in lipolytic and lipogenic genes, resulting in accumulation of lipid droplets in the gut of fish. Histological examination revealed no pathological disorders in the guts of the fish.
This study assesses the effect of inclusion of n–3 C18 rich oils on nutrient profile and quality of flesh in gilthead seabream (≈ 61.5 g) after feeding isoproteic and isolipidic diets in which camelina seed (CSO) or chia oil (CO) totally or partially replaces fish oil (FO) for 110 days. Fillet fatty acid (FA) profile reflects dietary FA profile, characterized by increased C18 polyunsaturated FA (PUFA) and a reduced highly unsaturated FA, whereas n–3/n–6 ratios are increased in fish fed diets with CSO or CO content. However, indices of atherogenicity and thrombogenicity, calculated from the fillet FA profile as indices for the health quality for consumers, are reduced with dietary addition of CSO or CO due to the increased fillet content of C18 n–3 PUFA in CSO and CO fed fish. In spite of the differences in fillet FA profiles, sensory quality of flesh does not vary among fish from different dietary groups. Instrumental texture and color analyses reveal significantly different values in cooked fillets in comparison to the raw fillets. Overall, dietary inclusion of CSO or CO enhances the nutritional value of fish flesh as well as the production of healthier fillets.
Practical Applications: This study suggests fish oil could be totally replaced with camelina or chia oil in the diet of gilthead sea bream without negatively affecting sensory characteristics. The dietary inclusion of these oils could enhance the nutritional quality of fish fillets, and could receive wide application in the aquafeed and animal feed producing sector.
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