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ARS Home » Southeast Area » Stuttgart, Arkansas » Harry K. Dupree Stuttgart National Aquaculture Research Cntr » Research » Publications at this Location » Publication #377087
Research Project: Enhancing the Production of Hybrid Striped Bass Through Improved Genetics, Nutrition, Production Management, and Fish Health

Location: Harry K. Dupree Stuttgart National Aquaculture Research Cntr

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

Author
item BOCKUS, ABIGAIL - Louisiana Universities Marine Consortium
item Rawles, Steven - Steve
item SEALEY, WENDY - Us Fish And Wildlife Service
item CONLEY, ZACHARIAH - Us Fish And Wildlife Service
item GAYLORD, T. GIBSON - Us Fish And Wildlife Service

Submitted to: Aquaculture
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/21/2021
Publication Date: 6/24/2021
Citation: Bockus, A.B., Rawles, S.D., Sealey, W.M., Conley, Z.B., Gaylord, T. 2021. Effect of dietary additives Thermal Care™, Bio-Mos®, and GroBiotic® A on rainbow trout (Oncorhynchus mykiss) performance at elevated temperature. Aquaculture. 544. https://doi.org/10.1016/j.aquaculture.2021.737084.
DOI: https://doi.org/10.1016/j.aquaculture.2021.737084

Interpretive Summary: Global mean surface temperature is predicted to increase 1 – 3.7C by the year 2100. This will result in warmer culture conditions for a variety of aquaculture species, including freshwater trout. One of the major physiological consequences of increasing culture temperature is an increase in energetic and metabolic demand. At sublethal elevated temperatures, fishes exhibit higher feed intake to support these temperature-induced physiological shifts. However, warmer culture conditions also result in a variety of changes that affect digestion and nutrient assimilation. Higher temperatures decrease feed efficiency, decrease protein and energy digestibility, and decrease feed retention and utilization. These effects can lead to changes in body composition, higher maintenance rations, and elevated protein and energy requirements. Dietary additives are being widely used across animal industries to combat both biological and environmental stressors. Three dietary additives of commercial interest to the aquaculture industry are Thermal Care, Bio-Mos, and Grobiotic A. Thermal Care is a combination of plant extracts and inactivated yeast advertised as a feed ingredient designed to combat thermal stress in milk cows. Bio-Mos and GroBiotic A are both prebiotics with well-documented benefits across farmed agricultural and aquaculture animal groups. A 12-week feeding trial was conducted to test the ability of Thermal Care, Bio-Mos, or GroBiotic A to facilitate production performance in rainbow trout reared under routine (15C) or elevated (18C) temperatures. Rearing rainbow trout at 18C may enhance production performance during the early stages of the grow-out process, but by 12 weeks, fish at 18C showed increased feed intake and decreased feed efficiency. Also, trout at 18C had lower protein content, and lower retention of protein and energy from the feed. There was preliminary evidence that Thermal Care improved rainbow trout growth 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. 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.

Technical Abstract: This study examined the effects of 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 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 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. 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.