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ARS Home » Pacific West Area » Aberdeen, Idaho » Small Grains and Potato Germplasm Research » Research » Publications at this Location » Publication #385793

Research Project: Improving Nutrient Utilization to Increase the Production Efficiency and Sustainability of Rainbow Trout Aquaculture

Location: Small Grains and Potato Germplasm Research

Title: Effects of elevated temperature and dietary additives Thermal Care™, Bio-Mos®, and GroBiotic® A on rainbow trout (Oncorhynchus mykiss) performance

item BROKUS, ABIGAIL - Louisiana Universities Marine Consortium
item Rawles, Steven - Steve
item Sealey, Wendy
item CONLEY, ZACHARIAH - Department Of Fish And Wildlife
item GAYLORD, THOMAS - Department Of Fish And Wildlife

Submitted to: Aquaculture
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/21/2021
Publication Date: 6/24/2021
Citation: Brokus, A., Rawles, S.D., Sealey, W.M., Conley, Z.B., Gaylord, T.G. 2021. Effects of elevated temperature and dietary additives Thermal Care™, Bio-Mos®, and GroBiotic® A on rainbow trout (Oncorhynchus mykiss) performance. Aquaculture. 544:Article e737084. Available:

Interpretive Summary: The effects of climate change-induced increases in air temperature and reduced water flow rates can produce stressful culture conditions for aquacultured fish. Numerous commercially available dietary additives claim to improve production of aquaultured fish; however there is often insufficient efficacy data to support these claims. USFWS and ARS scientists at the Bozeman Fish Technology Center investigated the ability of three dietary additives to mitigate negative climatic-induced effects. Research results identified hematological markers of climatic stress in rainbow trout. Using these climatic stress markers, researchers detected no noticeable benefits of the tested dietary additives on rainbow trout production efficiency.

Technical Abstract: This study examined the effects of elevated temperature and dietary Thermal Care, Bio-Mos and GroBiotic A on production performance and blood chemistry parameters in rainbow trout (Oncorhynchus mykiss) under optimal (15C) and supraoptimal (18C) culture temperatures. Rainbow trout under supraoptimal thermal conditions (18C) at 18C exhibited increased growth and feed intake but no change in feed efficiency for 6 weeks. This suggests that rearing fish at 18C may enhance production performance during the early stages of the grow-out process. By 12 weeks, fish at 18C showed increased feed intake, decreased feed efficiency, but no change in growth. Additionally, fish at 18C had lower protein content, protein retention efficiency, and energy retention efficiency. Elevated temperature did not change relative maximum swimming speed but did increase hematological parameters, thereby increasing the fish’s oxygen supply capacity. There was preliminary evidence that Thermal Care improved rainbow trout growth under optimal thermal conditions (at 15C). However, fish fed Thermal Care at 18C exhibited increased feed intake but one of the lowest final fish weights leading to the lowest feed efficiency. Additionally, Grobiotic A impacted acid-base balance through changes in blood pH, TCO2, and HCO3- although the relevance of these interactions remains to be determined. By the end of the experiment, there were no noticeable benefits of including Thermal Care or Bio-Mos or GroBiotic A on production performance at either culture temperature.