Maternal Dietary Choline Levels Cause Transcriptome Shift Due to Genotype-by-Diet Interactions in Rainbow Trout (Oncorhynchus mykiss)

Authors: FREIJ, KHALID - University Of Alabama; Cleveland, Beth; BIGA, PEGGY - University Of Alabama

Submitted to: Comparative Biochemistry and Physiology, Part D: Genomics and Proteomics
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/10/2024
Publication Date: 1/20/2024
Citation: Freij, K., Cleveland, B.M., Biga, P. 2024. Maternal dietary choline levels cause transcriptome shift due to genotype-by-diet interactions in Rainbow Trout (Oncorhynchus mykiss). Comparative Biochemistry and Physiology, Part D: Genomics and Proteomics. 49:101193. https://doi.org/10.1016/j.cbd.2024.101193.
DOI: https://doi.org/10.1016/j.cbd.2024.101193

Interpretive Summary: The nutrient profile of rainbow trout eggs is affected by what foods the female broodstock consumes during egg development. The rainbow trout embryo relies on egg-derived nutrients throughout development, including the first three weeks after hatching. Thus, optimizing the egg nutrient profile through strategies aimed at broodstock nutrition can benefit offspring growth and health. This study investigated whether choline levels in broodstock diets will affect offspring growth and nutrient partitioning, and characterized gene expression patterns associated with the response. Although supplementing choline in broodstock diets did not improve offspring growth, changes in gene expression were detected that indicate effects on muscle growth and fat metabolism. These findings indicate that broodstock nutrition can impact metabolism in rainbow trout offspring and contribute to the development of nutritional strategies that improve production efficiency.

Technical Abstract: The objective of this study was to identify metabolic regulatory mechanisms affected by choline availability in rainbow trout (Oncorhynchus mykiss) broodstock diets associated with increased offspring growth performance. Three customized diets were formulated to have different levels of choline: (a) 0% choline supplementation (Low Choline: 2065 ppm choline), (b) 0.6% choline supplementation (Medium Choline: 5657 ppm choline), and (c) 1.2% choline supplementation (High Choline: 9248 ppm choline). Six all-female rainbow trout families were fed experimental diets beginning 18 months post-hatch until spawning; their offspring were fed a commercial diet. Experimental broodstock diet did not affect overall choline, fatty acid, or amino acid content in the oocytes (p > 0.05), apart from tyrosine (p = 0.05). Offspring body weights from the High and Low Choline diets did not differ from those in the Medium Choline diet (p > 0.05); however, family-by-diet and sire-by-diet interactions on offspring growth were detected (p = 0.05). The High Choline diet did not improve growth performance in the six broodstock families at final harvest (520-days post-hatch, or dph). Numerous genes associated with muscle development and lipid metabolism were identified, including myosin, troponin C, and fatty acid binding proteins, which were associated with key signaling pathways of lipid metabolism, muscle cell development, muscle cell proliferation, and muscle cell differentiation. These findings indicate that supplementing broodstock diets with choline does regulate expression of genes related to growth and nutrient partitioning, but does not lead to growth benefits in rainbow trout families selected for disease resistance.