Date of Award

8-2026

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Animal and Veterinary Sciences

Committee Chair/Advisor

Susan Duckett

Committee Member

Troy Farmer

Committee Member

Elliot Jesch

Committee Member

William Bridges

Committee Member

Charles Rosenkrans

Abstract

In rainbow trout (Oncorhynchus mykiss), skeletal muscle growth is the driving force behind growth efficiency, fillet yield, and final product quality. Despite these traits’ economic value, there are still gaps in current knowledge surrounding how muscle develops throughout production, and further, how interventions in nutrition and molecular homeostasis could optimize performance. The three following studies aim to address these challenges by characterizing skeletal muscle development and evaluating molecular and nutritional strategies to enhance muscle growth performance in rainbow trout.

The first study aimed to set the groundwork for basal growth, muscle deposition, fatty acid composition, and gene microRNA expression in white and red/pink muscle expectations from a single genetic strain (FLD-ERW) and cohort of rainbow trout across six developmental stages (6-19 months of age). As fish developed throughout the study, growth characteristics and fillet yield increased; muscle growth was mainly governed by white muscle growth. At the same time, genes like pax7a/b, myf5, gh1/2, and igf1 expression generally decreased across development, while expression from genes such as mtor, tnfa, and miR-133a-3p/5p was more tissue specific.  These changes across development point to ongoing muscle remodeling and maturation.

The second study evaluated potential delivery methods and the subsequent biological response to exogenous miR-133a-3p administration. Early juvenile rainbow trout were grown out for 14 days after being treated using injection (INJ) or immersion (IMM) of a miR-133a-3p AgomiR (MIR) or 1X phosphate buffered saline (PBS) (CON). Growth responses were fairly moderate in the short-term study, that said, MIR treatments successfully modulated expression of genes involved in muscle growth and differentiation. Most importantly, these results demonstrate the feasibility of a non-invasive miRNA delivery method, providing a baseline for future research into miRNA-mediated growth regulation in aquaculture.

The third and final study, aimed to evaluate the effects of the dietary supplementation of curcumin and piperine on juvenile rainbow trout under optimal (14°C) and elevated (19°C) water temperatures. Elevated water temperatures improved growth performance and growth-related signaling pathways, while curcumin and piperine (CUR:PIP) supplementation altered metabolic, endocrine, and stress-associated responses. That said, reduced feed acceptance could have contributed to the lower growth performance in supplemented fish. These data highlight the importance of evaluating the effects of phytogenic feed additives, especially when the goal rises beyond fish health.

Together, these studies demonstrate that rainbow trout skeletal muscle growth is a highly complex system regulated through coordinated interactions between age, muscle fiber type, endocrine signaling, post-transcriptional regulation, nutrition, and environment. These findings shed new light on the biological mechanisms that govern muscle growth and identify potential opportunities for improving production, efficiency, and sustainability in aquaculture systems.

Author ORCID Identifier

0009-0007-5499-963X

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Available for download on Tuesday, August 31, 2027

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