Carotenoid-enriched Dunaliella sp. PM018 as a microalgal feed ingredient for rainbow trout (Oncorhynchus mykiss) fry

Description

This dataset includes growth and carotenoid data for Dunaliella sp. PM018 and dietary and growth performance data from rainbow trout (Oncorhynchus mykiss) fry fed diets containing the microalga.

Steps to reproduce

Dunaliella sp. PM018 was cultured in Guillard f/2 medium in triplicate 500-mL Erlenmeyer flasks containing 300 mL, inoculated at 4.76 × 10^5 cells mL−1. Cultures were maintained for 9 days at 22 ± 1 °C, pH 8.0, 60 µmol m−2 s−1 irradiance and a 12:12 h light photoperiod, with manual agitation three times daily. Cell productivity and specific growth rate were calculated from initial and final cell concentrations and cultivation time. Cultures in the exponential phase were scaled to 3 L using a 1:10 inoculum ratio. Carotenogenesis was induced by increasing NaCl to 1.0 M and exposing cultures to continuous high irradiance (460 µmol m−2 s−1). The resulting dried biomass was stored under cool, dry conditions until pigment analysis and diet preparation. Total carotenoids were extracted in triplicate from 30 mg dried biomass using 3 mL 100% acetone. Samples were vortexed for 3 min, sonicated in an ice bath for 5 min, and the cycle was repeated twice before storage at −20 °C for 24 h. Samples were subsequently subjected to repeated vortexing, sonication and centrifugation (2,000 × g, 5 min, 4 °C) until the biomass pellet was colorless. Supernatants were combined and adjusted to 30 mL with acetone. Chlorophyll a, chlorophyll b and total carotenoids were quantified by UV–Vis spectrophotometry (GENESYS 40/50) at 661.6, 644.8 and 470 nm, respectively, using acetone as blank. β-carotene was quantified by HPLC–DAD after filtration through 0.45-µm PTFE filters and injection of 8 µL onto a Poroshell 120 EC C18 column (4.6 × 50 mm, 2.7 µm). A total of 360 rainbow trout (Oncorhynchus mykiss) fry (1.78 ± 0.008 g) were randomly assigned to 12 experimental units (30 fish/unit), with four treatments and three replicates, in a 76-day completely randomized feeding trial. Treatments were a basal diet (BD), basal diet with synthetic carotenoid (Carophyll® Pink), basal diet with 10 g kg−1 non-stressed Dunaliella biomass (BD-DSC), and basal diet with 10 g kg−1 stressed biomass (BD-DSE). Diets were isoproteic (50% crude protein) and isoenergetic (3.69 Mcal kg−1 digestible energy). Fish were fed 4.5% body weight day−1 in eight equal daily feedings, with rations periodically adjusted to body weight and temperature. Growth was assessed every 10 days by sampling 15 fish per experimental unit. Hematological and biochemical variables were determined from blood samples, and liver and anterior intestine were evaluated histologically at the end of the trial. Microalgal and feeding-trial data were statistically analyzed in R 4.5.0. Microalgal data were evaluated using GLMMs, Kruskal–Wallis/Dunn tests, and Mann–Whitney U tests as appropriate; feeding-trial variables were analyzed by ANOVA, with normality and variance homogeneity assessed beforehand. ART was used when assumptions were not met, followed by Tukey HSD or appropriate nonparametric comparisons. Statistical significance was set at P < 0.05.

Institutions

• Universidad Estatal Península de Santa Elena

  Guayas, La Libertad
• Universidad de las Fuerzas Armadas ESPE

  Pichincha, Sangolquí
• Universidad Estatal de Bolívar

  Bolívar, Guaranda

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