Deposition and mobilization of lipids varies across the rainbow trout fillet during feed deprivation and transition from plant to fish oil-based diets

Hepatic Fatty Acid and Transcriptome Profiles during the Transition from Vegetable‐ to Fish Oil‐Based Diets in Rainbow Trout (Oncorhynchus mykiss)

“…Previous findings from this study have been published that describe growth performance and changes in the fillet fatty acid profile prior to, during, and after completion of the finish diet period (Cleveland et al, 2018). These results indicate that while a finishing diet is effective at elevating fillet LCn3 content, fillet content of LCn3 remains lower compared to fish continuously fed a fish oil diet.…”

“…Procedures and protocols involving live fish received approval from the Institutional Animal Care and Use Committee (IACUC) and were performed according to IACUC guidelines (protocol #108). Full details of the husbandry protocols, diet formulation, and experimental design are published (Cleveland et al, 2018). Briefly, fish (~10 months, 250.2 ± 4.0 g) were randomly distributed among nine circular tanks (0.9 m 3 capacity), with 39 fish per experimental tank.…”

“…Notable differences in the fatty acid profiles of the two diets were as follows: the FO diet contained higher concentrations of saturated fatty acids (SFA), LCn3, and LCn6 by approximately 2.3‐, 8‐, and 10‐fold, respectively. In contrast, the VO diet displayed greater concentrations of monounsaturated fatty acids (MUFA) and several 18‐carbon unsaturated fatty acids, including oleic acid (18:1n‐9), linoleic acid (18:2n‐6), and alpha‐linolenic acid (ALA, 18:3n‐3) that were 2.5‐, 2.3‐, and 17‐fold higher than the FO diet (Cleveland et al, 2018).…”

“…Samples (n = 9 per treatment) were pulverized at liquid nitrogen temperature and the powder stored at −80°C until fatty acid content was determined by fatty acid methyl ester (FAME) analysis. FAME derivatization was based upon a previously developed one‐step method using acetyl chloride (Lepage and Roy, 1986) as described in Cleveland et al (2018). FAME were quantified by gas chromatography with flame ionization detection (GC‐FID) as described previously (Picklo and Murphy, 2016).…”

Fishmeal alternative from renewable CO2for rainbow trout feed

“…However, this increase did not result in elevated whole‐body EPA or DHA, possibly due to the high amounts of fish oil (approximately 13%) already in the diets, which is a rich source of LC‐PUFA. Generally, FADS6 and elongase are upregulated when dietary levels of LC‐PUFA are reduced, such as when being fed vegetable oil‐based diets that often lack DHA and EPA (Cleveland, Raatz, Hanson, Wickramaratne, & Picklo, 2018). Therefore, SCP could be particularly advantageous as a protein substitute for its capacity to boost endogenous synthesis of LC‐PUFA when using diets containing vegetable oils.…”