Enrichment of hufa contents of the earthworm Eisenia fetida and it's use as feed for the shrimp Penaeus vannamei

This study was carried out to determine HUFA-enrichment and potential use of the earthworm Eisenia fetida in the diets for the Pacific white shrimp Penaeus vannamei. In the 1st Experiment, fatty acid (FA) compositons of E. fetida and fish meal (FM) were compared and the effects of different compost-mixtures on growth, reproduction and vermicompost production of E. fetida were studied. In the 2nd and 3rd Experiments, the effects of a commercial enrichment-emulsion in various doses (0, 10, 25 and 50%) and duration (12, 24, 48 and 96 h) in two different enrichment techniques (with or without bedding) on FA composition of E. fetida were investigated. In the 4th Experiment, enrichment potential of fish meal/oil (FO) for earthworms, in various doses (0, 2.5, 5.0 and 10%) and periods (24, 48 and 96 h) was also studied. In the 5th Experiment, a suitable replacement level of earthworm meal (EM) for FM was studied in five replacement levels (0, 25, 50, 75 and 100%) and the effects were assessed on the growth, feed consumption and fatty acid composition of P. vannamei. Among the compost mixtures, 50% caw dung+25% horse dung+25% tea composts were found to be suitable. Freeze-dried EM had a crude protein level of 62.1%, ash level of 9.4%, and lipid level of 6%. Dominant FA's in EM were found to be PUFA's (48.30%), followed by MUFA's (25.74%) and SFA's (20.08%). FA composition of EM was rich, but it's DHA content, compared to that (23.9%) of FM, was quite low (0.38%). Dose, Time as well as Dose x Time interactions were found to be significantly impor-tant on all FAs in the enriched-groups. Enrichment sharply increased DHA levels up to 8-9% in 24-h, 10-15% in 48-h and 14-18% in 96-h. Enrichment for 96-h resulted in a sharp rise at n-3/n-6 ratios from 1.35 (control group) to 3.72 in the enriched-groups. 12-h period is suggested to be suitable for enrichment without bedding, while longer enrichment periods are recommended with bedding-media. 96-h enrichment boosted DHA to levels between 16.3 and 17.74% (9.37-fold over the control). FO-enrichment in 24-h also increased DHA levels by 16-fold in the group 10/BY (up to 13.55%). Increased inclusion level of EM in the diets enhanced PUFA levels of the shrimp tissues, and the tested diets sustained high survivals (62-87%), good growth (3.39 and 4 g) and FCRs (1.6-2.25) at the end of five-weeks growth-period. FA's, growth and feed consumption results of this study have verified that a replacement level of 100% FM by EM is possible in the diets for the Pacific white shrimp.