The effect of different live feed organisms and formulated diet on lumpfish (Cyclopterus lumpus) larval development: part 2—dietary effects on skeletal deformities related to gene expression

Abstract Early-life nutrition plays a critical role in shaping developmental trajectories, including skeletal formation, possibly through mechanisms of nutritional programming. To date, little is known about the early-stage development in lumpfish, their nutritional requirements, and how different start-feeding regimes influence their growth and development. In this study, Cyclopterus lumpus larvae were fed five different dietary regimes (Enriched Artemia , copepods, cirripeds, copepods + cirripeds (mixed diet), and dry feed) up to 21 days post hatch (DPH) and thereafter weaned to a common dry feed up to 35 DPH. Early feeding with enriched Artemia nauplii supported the fastest early growth, the highest survival rates, and the greatest degree of ossification compared to the other dietary regimes. Because of the high differences in ossification rates and anomalies between dietary regimes, we used molecular tools to identify which nutritional deficiencies and/or metabolic imbalances caused the differences in bone development (osteogenesis). Transcriptomic analysis revealed that the larval groups with the highest deformities occurrence and lowest ossification rates (copepods and dry feed groups) showed a marked upregulation of lipid scavenger receptors, fatty acid and lipoprotein metabolism, and retinoid metabolism. The upregulation of lipid scavenger receptors also suggests increased levels of oxidized lipids or lipid peroxidation products. Elevated and prolonged presence of oxidized lipids is known to impair osteoblast differentiation and bone matrix formation by inducing oxidative stress, inflammatory signaling, and attenuating osteogenic pathways, negatively influencing osteogenesis. These data indicate that optimal early feeding is essential to support redox balance, osteoblast differentiation, and normal skeletal formation.