n-3 LC-PUFA Enrichment Protocol for Red Earthworm, Eisenia fetida: A Cheap and Sustainable Method

Abstract

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 timeperiods, up to 96h. 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).

Cutting without a Knife: A Slice-Selective 2D 1H–13C HSQC NMR Sequence for the Analysis of Inhomogeneous Samples

“…The latter is consistent with the literature which has reported that E. fetida can rapidly enrich themselves with long-chain polyunsaturated fatty acids with maximal uptake after only 24 h . On the other hand, in slice (d), which includes contributions from both the stomach and head region, the −CHCH- CH 2 -CHCH– peak is not as large, consistent with the process mainly occurring in the stomach.…”

“…This suggests that either the unsaturations are being synthesized from 13 C enriched algal components and/or polyunsaturated species/moieties are being concentrated from the food source. The latter is consistent with the literature which has reported that E. fetida can rapidly enrich themselves with long-chain polyunsaturated fatty acids with maximal uptake after only 24 h. 48 On the other hand, in slice (d), which includes contributions from both the stomach and head region, the −CH�CH-CH 2 -CH�CH− peak is not as large, consistent with the process mainly occurring in the stomach. In slice (e), which includes the stomach and clitellum, the peak in the green box (associated with CH 3 groups) is larger than that in the blue box.…”

Stress Tolerance of African Catfish (Clarias gariepinus, Burchell, 1822) Larvae Fed on Spirulina platensis or Eisenia fetida in Partial Replacement of Caridina nilotica in Formulated Diets

“…This could be attributed to poor growth and increased chitin content (non-digestible protein) in diet T6 due high inclusion levels of E. fetida that could have decreased its digestibility (Musyoka et al, 2019). Thus, reduced supply of nutrients for development and enhanced stress tolerance in C. gariepinus larvae (Kumlu et al, 2021). Furthermore, high stress indices were recorded possibly because lipid (10.4/% dry matter) content could have increased PUFA beyond optimal levels for C. gariepinus larvae and could have caused physiological malfunctioning and suppression of stress management abilities of the larvae (Rufchaei et al, 2019).…”

“…Yet, information from such evaluations could contribute to the development of aquafeeds that guarantee fish larvae health and quality. This is because nutritional content in a diet has proportionate effects on fish larvae growth, immunity, and general robustness (Kreutz et al, 2008;Kumlu et al, 2021). This study aimed at determining the effects of partially replacing C. nilotica with S. platensis or E. fetida on stress tolerance of C. gariepinus larvae.…”