Date of Award


Degree Type


Degree Name

Master of Science




Dr. Louise Milligan


Much is known about carbohydrate metabolism in adult fish, however virtually

nothing is known about this in early life stages. The purpose ofthis study was to examine carbohydrate metabolism at various stages of early development (from fertilization to free-feeding) in rainbow trout (Oncorhynchus mykiss). Total body glycogen and free glucose increased throughout development, with the greatest changes occurring at hatch and free-feeding stages. Lactate content increased 3-fold at hatch, and persistedthroughfree-feeding. Glycogenphosphorylaseactivitywasnotdetecteduntil 21 dpf and lactate dehydrogenase activity (LDH) not until hatch. Taken together, the increase in glycogen phosphorylase, LDH and glycogen content suggests that embryos areinpreparationforlocomotoryactivityfollowinghatch. Consistentwiththisidea, dechorionated embryos had an increase in glycogen compared to their unfed counterparts. Also, free-feeding likely provides substrates to support glycogenesis seen in free-feeding larvae, as indicated by decreased glycogen content in food-restricted larvae.



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