Aquaculture America 2020

February 9 - 12, 2020

Honolulu, Hawaii

GROWTH AND IMMUNE RESPONSES OF CULTURED BURBOT Lota lota maculosa FED VARIED INCLUSIONS OF SOY PROTEIN SOURCES

 
Timothy J. Bruce *,  Luke P. Oliver,  Jie Ma, Brian C. Small ,  Ronald  W. Hardy , Michael L. Brown, Steven R. Craig,  and  Kenneth  D. Cain
 
Department of Fish and Wildlife Science s
University of Idaho
875 Perimeter Dr. MS1136
Moscow, ID, 83844-1136
tbruce@uidaho.edu
 

Burbot (Lota lota maculosa ) are the only freshwater member of the cod family (Gadidae) and are a new species for commercial aquaculture.  Burbot culture  methods and feeding trials at the University of Idaho are  being optimized for commercial burbot production. T his "freshwater cod"  species  could  provide  diversification  for freshwater salmonid and other aquaculture operations , given its desirable fillet  quality and growth potential .  Burbot n utrition research  is  necessary to further define dietary requirements and the potential of this species to utilize more sustainable plant-based proteins.  A 91-day feeding trial and subsequent 28-day pathogen challenge was completed and growth performance, survival, and immune parameters in juvenile burbot were evaluated. Dietary treatments included a fishmeal reference diet (FM), and 25% and 50% fishmeal replacements with soybean meal (SBM), soy protein concentrate (SPC) and bioprocessed soybean meal (BSBM). Growth results indicated a difference in relative growth (RG; P =0.01) and specific growth rate (SGR; P=0.02) among dietary treatments, with the fish fed FM and SBM-25% performing better than the SPC-50% and BSBM diets. Analysis of distal intestine samples discerned no differences in lamina propria thickness (P=0.489) or cellularity (P=0.979), and the amount of connective tissue of the submucosa was found to be similar (P=0.972), indicative of no diet-related complications. Immediately following the feeding trial, burbot were challenged (triplicate groups of 25 fish/tank) with a virulent strain of Aeromonas sp. while remaining on their respective dietary treatments.  At day 28 post-challenge, no diet-related effects were found in cumulative percent mortality (P=0.17), and i mmune metrics post-challenge  were not differen t for ser um lysozyme (P=0.975) or respiratory burst activity of isolated head kidney-derived leukocytes (P=0.796). Overall, results indicate that low-level FM replacements with SBM and SPC are applicable for incorporation into burbot diets and long-term feeding of soy-based proteins does not impair disease resistance or innate immune function. Utilizing soy-based protein sources for commercial burbot culture will expand the use of soy ingredients in aquaculture and provide potential producers with a more cost-effective alternative to high fishmeal diets.