Flaxseed oil and clove leaf essential oil in Zebrafish diet (Danio rerio)

Abstract

Flaxseed oil is recognized as the plant source richest in α-linolenic acid, whereas clove leaf essential oil has a strong antioxidant capacity. The objective of this study was to determine the in vitro antioxidant capacity of diets containing a combination of flaxseed oil (FO) and clove leaf essential oil (CLEO), as well as to use zebrafish (Danio rerio) to assess their effect on the animals’ growth. Fifty days after hatching, a total of 420 male specimens (0.29 ± 0.04 g) were divided into seven groups for each diet and fed for 55 days to be used, with the diets being: control, absent FO and CLEO; 3% FO + 0.5% CLEO; 3% FO + 1% CLEO; 6% FO + 0.5% CLEO; 6% FO + 1% CLEO; 9% FO + 0.5% CLEO and 9% FO + 1% CLEO. Antioxidant activity was determined through DPPH (2,2-diphenyl-1-picrylhydrazyl) tests, showing interaction effect between factors (FO x CLEO, p < 0.05); the diets containing 1% combined with 3, 6 or 9% of FO presented means higher than those of the 0.5% diets. No mortality was observed during the experiment. For final weight and weight gain, there was no interaction effect (p > 0.05), only isolated effect for FO, with the fish fed 6 and 9% diets having the best results. Final total length and specific growth rates showed interaction effect (p < 0.05). As for specific growth rates, the best response was that of the diet with 6% FO and 0.5% CLEO. Final length showed increase with FO levels, even when there was association with 0.5 or 1% of CLEO. Therefore, combined use of 9% of FL with 0.5% of CLEO is recommended for zebrafish.

The effect of laboratory diet and feeding on growth parameters in zebrafish

“…The post-hoc comparison also revealed each diet to differ significantly between each other except for wheat gluten compared to 9% FO and 0.5% CLEO 26,30 .…”

“…Sub-group analysis revealed 50% FM (category 3) and GM300 combined with brine shrimp (category 6) to be optimal within their respective categories for juvenile length gain and were therefore compared against wheat gluten (category 2), defatted prepupae meal (category 4) and 9% FO + 0.5% CLEO (category 5) in the overall analysis 26,30,35,37 . The analysis demonstrates a significant effect of diet on juvenile length gain (One-way ANOVA: F (4, 877) = 279.6, p < 0.0001) (Fig.…”

“…Female zebrafish tend to grow heavier and longer than male zebrafish and therefore an unequal split in sex may have impacted the results 49,50 . However, 50% of the included studies did not disclose a sex split and one of the studies that did only used males 26 . Other factors which may have significantly impacted the growth findings include strain of fish, water quality, temperature, availability of feed and population density 48 .…”

“…The studies reported significant effects on juvenile growth with differing zebrafish feeds with no effect on overall survival observed [24][25][26][27] . A common finding amongst authors was a positive correlation between protein content, pro-biotic, Chlorella spirulina (Chlorella sp.)…”