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    DHA enrichment of the red earthworm Eisenia fetida for improving its potential as dietary source for aquaculture
    (Elsevier, 2018) Kumlu, Metin; Beksari, Asuman; Eroldogan, O. Tufan; Yilmaz, H. Asuman; Sariipek, Merve; Kinay, Enes; Turchini, Giovanni M.
    This study aimed at assessing the potential of omega-3 fatty acids enrichment in the red earthworm Eisenia fetida. Specifically, the investigation focused on the effects of a commercial enrichment emulsion (ES) supplied at graded doses (0, 10, 25 and 50 g ES/100 g of compost) and at different enrichment times (0, 12, 24, 48 and 96 h) on the resulting fatty acids composition of red earthworm reared with or without additional bedding materials. In the first experiment (bed-free technique), inclusion of ES, in the highest tested dose (50 g/100 g compost), exerted stress on the earthworms resulting in high mortality, while the use of bedding in the second experiment led to safer but slightly reduced enrichment. Dominant fatty acids in earthworms were found to be PUFA (51.08-53.04 mol%), followed by MUFA (25.95-26.90 mol%) and SFA (21.16-22 mol%). Non-enriched earthworms contained some of the PUFA, important for cultured marine species, including 18:2n-6, 18:3n-3 and 20:5n-3 (EPA), whereas in contrast, 22:6n-3 (DHA) is very low. Overall the results of this study have, for the first time, showed that LC-PUFA, and especially DHA, contents of E. fetida can be enriched to levels much higher than those of the control (non-enriched) groups. In bed-free technique, DHA accumulation in the worms increased from 0.31 mol% (0 h) to 14.38-14.63 mol% at 12 h, 9.65-9.81 mol% at 24 h, 10.65-15.41 mol% at 48 h and finally 15.81-18.31 mol% at 96 h. In the bedding technique, DHA also rose from the base level to 5.27-5.97 mol% at 12 h, 5.25-8.60 mol% at 24 h, 11.06-13.01 mol% at 48 h and finally 14.05-17.14 mol% at 96 h. In the bedding technique, DHA increased linearly for up to 9.6 fold, while this increase was fluctuating in the bed-free technique, reaching 8.7 fold over the non-enriched controls. Throughout the experiments, n-3/n-6 ratios rose from 1.35-1.56 in the controls to 3.38-3.72 in the enriched-groups. As a result, 12-h enrichment time is suggested to be suitable for a fast boosting of DHA in the earthworms with bed-free technique, while a longer period of up to 96 h is recommended with bedding technique at optimal dose of 25 g ES inclusion into 100 g compost. The present study showed that earthworm (E.fetida) can be successfully enriched in its DHA content; making it a novel and easily producible feed resource, particularly as broodstock feed, in aquatic hatcheries.
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    n-3 LC-PUFA Enrichment Protocol for Red Earthworm, Eisenia fetida: A Cheap and Sustainable Method
    (Central Fisheries Research Inst, 2021) Kumlu, Metin; Beksari, Asuman; Yilmaz, Hatice Asuman; Sariipek, Merve; Kinay, Enes; Turchini, Giovanni M.; Eroldogan, Orhan Tufan
    This study assessed the potential of omega-3 long chain polyunsaturated fatty acids (n-3 LC-PUFA) enrichment in red earthworm (Eisenia fetida, REW), via the addition of fish oil (FO, anchovy oil) to the culture-compost. FO addition to compost was tested at graded inclusion doses (0, 2.5, 5 and 10 g/100 g compost) and for different time-periods, up to 96 h. Dose, time, as well as dose and time interactions of FO compost enrichment had significant effects on all fatty acids of earthworm bodies. The enrichment with 10 g FO/100 g compost sharply increased DHA levels of the worms (14.01 mol%) within just 24 h, compared to the control group (0.92 mol%). Similar increases (ranging between 10.99 and 15.55 mol%) occurred only after 48 and 96 h in lower FO enrichment levels (2.5 and 5.0 g/100 g compost, respectively). Therefore, it was concluded that, to obtain maximum n-3 LC-PUFA enrichment efficiency in REW, an enrichment period of 24 h is ideal and recommended for the 10 g FO/100 g compost, whereas longer enrichment periods (48-96 h) are more suitable for lower levels of FO inclusions (2.5 or 5 g/100 g compost).
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    Response of Fatty Acid Composition of the Green Tiger Shrimp Penaeus semisulcatus During the Overwintering Period
    (Central Fisheries Research Inst, 2019) Kumlu, Metin; Kinay, Enes; Yilmaz, Hatice Asuman; Beksari, Asuman; Eroldogan, Orhan Tufan; Sariipek, Merve
    Response of proximate and fatty acid (FA) composition of the green tiger shrimp Penaeus semisulcatus in relation to changing water temperatures during over wintering (for 8-weeks at 11-16 degrees C) and then refeeding periods (at 28 degrees C for a further 2-weeks) was investigated in this study. The shrimps did not appear to need to catabolise their either body proteins or lipids during the overwintering period, as the feeding was not ceased completely. While muscle protein, ash and dry matter compositions of the shrimps did not change by changing temperature, lipid increased from 1% during the overwintering period to 1.2% during the recovery period (P<0.01). Saturated FAs (SFA), mono-unsaturated FAs (MUFA), and partially poly-unsaturated FAs (n-6 PUFA) declined, on the contrary, n-3 PUFA significantly rose in the muscle and hepatopacreas during the cold exposure. Shrimps tended to consume especially SFA and, to a lesser degree, MUFA under sub-optimal conditions (P<0.01). PUFA and LC-PUFA appeared to be selectively retained or even elevated in the shrimp muscle during the cold season. Over wintering strategy might generate additional benefit for a heathier food supply for human nutrition, as shrimps can be enriched for LC-PUFA, by simply keeping them under cold water temperatures (10-15 degrees C) during overwintering period, with minimal cost of feeding.