Thiamine supplementation improves survival and body condition of hatchery-reared steelhead (Oncorhynchus mykiss) in Oregon

Veterinary Sciences
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Abstract

Early rearing of steelhead (Oncorhynchus mykiss) in Oregon hatcheries is often problematic; fry can become emaciated and die during the period between hatch and first feed. Thiamine (vitamin B1) deficiency has caused early mortality in salmonids; however, the thiamine status of Oregon’s steelhead populations is unknown, to date. Of the 26 egg samples from three Oregon hatcheries in 2019, 20 (77%) had thiamine levels < 10 nmol/g, and 13 of those samples (50%) had levels <6.5 nmol/g, suggesting the thiamine deficiency of adult, female steelhead. To investigate if thiamine deficiency was causally related to fry survival, females were injected with buffered thiamine HCl 50 mg/kg prior to spawning; additionally, a subset of eggs were supplemented via bath treatment with thiamine mononitrate (1000 ppm) at spawning. Cumulative fry mortality at 8 weeks post-hatch from thiamine-injected females was 2.9% compared to 13.8% mortality of fry without thiamine supplementation. Fry treated only with the thiamine via bath as eggs had a mortality rate of 6.9%. There were no additional improvements for the survival of fry from injected females that also received a thiamine bath. Furthermore, condition factors were greater in thiamine-supplemented fry than in those that received no thiamine. These data identify thiamine deficiency in Oregon steelhead and suggest supplementation with thiamine can mitigate early rearing mortality.

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Publication type Article
Publication Subtype Journal Article
Title Thiamine supplementation improves survival and body condition of hatchery-reared steelhead (Oncorhynchus mykiss) in Oregon
Series title Veterinary Sciences
DOI 10.3390/vetsci10020156
Volume 10
Issue 2
Year Published 2023
Language English
Publisher MDPI Journals
Contributing office(s) Columbia Environmental Research Center
Description 156, 11 p.
First page 156
Country United States
State Oregon
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