Changes in Serum Blood Parameters in Farmed Rainbow Trout (Oncorhynchus mykiss) Fed with Diets Supplemented with Waste Derived from Supercritical Fluid Extraction of Sweet Basil (Ocimum basilicum)

Abstract

The antimicrobial and immunostimulant proprieties of aromatic plant extracts have been widely described, but their effects on serum blood biochemistry in fish have not. For this study, we assessed the changes in serum blood biochemical parameters in rainbow trout fed with a fish diet supplemented with a basil supercritical extract (F1-BEO). Our hypothesis was that treatment and time would be associated with changes in 10 serum blood biochemical parameters. F1-BEO was added to a commercial feed (0.5, 1, 2, 3% w/w). The fish were fed for 30 days, and the blood samples were collected at 2 time points (15 and 30 days). A two-way ANOVA showed a significant effect of treatment, time, and interaction treatment × time on creatinine, urea, total protein, albumin, magnesium, and phosphorus (p < 0.05), a significant effect of both time and interaction treatment × time on cholesterol (CHOL), glutamic oxaloacetic transaminase (GOT), and glutamic pyruvic transaminase (GPT) levels, and a significant effect of time on triglycerides (p < 0.05). While changes in several of the parameters were observed, the levels remained within the normal range for rainbow trout. Notably, after 30 days there was a significant decrease in CHOL in fish treated with 0.5% and 1% w/w F1-BEO (p < 0.05). The statistically non-significant increase in GOT and GPT in the fish fed with F1-BEO up to 3% w/w indicated a positive effect of basil on liver health. Our findings suggest a potential use for basil extracts (for example., F1-BEO) in fish feed to reduce antibiotic use and improve fish welfare.

Ecotoxicity of basil (Ocimum Basilicum) extract in aquaculture feeds: Is it really eco-safe for the aquatic environment?

“…For this study, the effects of a basil extract (F1-BEO) as-is and supplemented in a commercial fish feed (based on the effectiveness observed in fish [Magara et al, 2022;Pastorino et al, 2022]) were assessed using model organisms for marine and freshwater ecosystems. Our findings suggest that the ecotoxicological responses were comparable in the freshwater and the marine ecosystem for organisms at the same trophic level.…”

“…The basil supercritical fluid extract (F1-BEO) was the same as that used in previous studies (Magara et al, 2022;Pastorino et al, 2022). F1-BEO was extracted by Exenia Group s.r.l.…”

“…Ecotoxicity bioassays were performed on: commercial feed (Alterna Eel, Skretting; ingredients: fish meal, fish oil, wheat red dog, wheat gluten, blood meal from poultry, a soya bean protein concentrate, swine haemoglobin, whey powder; proximate composition: protein 48 %, lipid 11 %, ash 8 %, fibre 1 %) supplemented with 3 % w/w F1-BEO (substance A) which is the feed with the higher basil extract inclusion by weight used by Magara et al (2022) and Pastorino et al (2022); the F1-BEO extract (substance B); a commercial feed (Alterna Eel, Skretting) without F1-BEO supplement (substance C).…”

“…Two recent studies assessed the long-term changes in serum blood biochemical parameters and biomarkers of antioxidant stress in rainbow trout (Oncorhynchus mykiss) fed with a commercial fish diet supplemented with a basil supercritical extract (F1-BEO) up to 3 % w/w (Magara et al 2022;Pastorino et al, 2022). Its ecotoxicity profile in aquatic ecosystems has not been assessed to date, however.…”