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United States Department of Agriculture

Agricultural Research Service

Research Project: INTEGRATION OF NUTRITIONAL, GENETIC AND PHYSIOLOGICAL APPROACHES TO IMPROVE PRODUCTION EFFICIENCY OF RAINBOW TROUT

Location: Small Grains and Potato Germplasm Research

Title: Evaluation of the ability of barley genotypes containing different amounts of ß-glucan to alter growth and disease resistance of rainbow trout Oncorhynchus mykiss.

Authors
item Sealey, W. - UNIV OF ID, HAGERMAN
item Barrows, Frederic
item Hang, An - RETIRED USDA-ARS ABERDEEN
item Johansen, K. - FORMER USDA-ARS HAGERMAN
item Overturf, Kenneth
item Lapatra, S. - UNIV OF ID, HAGERMAN
item Hardy, R. - UNIV OF ID, HAGERMAN

Submitted to: Animal Feed Science And Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: December 11, 2007
Publication Date: March 1, 2008
Repository URL: http://riley.nal.usda.gov/nal_web/digi/submission.html
Citation: Sealey, W., Barrows, F., Hang, A., Johansen, K., Overturf, K.E., Lapatra, S., Hardy, R. 2008. Evaluation of the ability of barley genotypes containing different amounts of ß-glucan to alter growth and disease resistance of rainbow trout Oncorhynchus mykiss. Animal Feed Science And Technology 141: 115-128.

Interpretive Summary: A feeding trial was performed to screen three types of barley containing different levels of glucan for their ability to influence growth, immune function, and disease resistance of rainbow trout. Three experimental diets were prepared by substituting each of three barely types containing different amounts of glucan, low, average and high glucan levels, respectively, for the entire wheat portion (321 g/kg) of the diet. An additional test diet which consisted of the control diet supplemented with commercially available yeast glucan product (MacroGard) at the manufacturer’s recommended level also was evaluated. Juvenile rainbow trout were full fed the test diets by hand for 9 weeks. At 3 and 9 weeks post weighing, fish were sampled for determination of immune response. At the conclusion of the feeding trial, fish remaining after sampling were pooled by diet; one subsample was examined for their ability to respond immunologically to a viral pathogen and two other subsamples were challenged by injection with a virulent strain of the same virus. Substituting barely flour for wheat flour in a fish-meal based diet did not substantially alter weight gain or body composition of rainbow trout. In contrast, positive effects of barley type on disease resistance were observed. Trout fed the average or high glucan barley types had survival rates similar to those fed the commercially available challenge material. The results indicate that select barley types can be substituted for wheat without significant detrimental effects on production efficiency while potentially increasing resistance to viral pathogens.

Technical Abstract: A feeding trial was performed to screen three barley genotypes containing different levels of '-glucan for their ability to influence growth, immune function, and disease resistance of rainbow trout. Three experimental diets were prepared by substituting each of three barely genotypes containing different amounts of '-glucan, low (38 g/kg), average (52 g/kg) and high (82 g/kg) '-glucan barley, respectively, for the entire wheat portion (321 g/kg) of the diet. An additional test diet which consisted of the control diet supplemented with commercially available yeast '-glucan product (MacroGard) at the manufacturer’s recommended level of 2 g/kg also was evaluated. Juvenile rainbow trout were fed the test diets by hand to satiation for 9 weeks. At 3 and 9 weeks post weighing, fish were sampled for determination of respiratory burst activity, and lysozyme and TNF-a expression. At the conclusion of the feeding trial, fish remaining after sampling were pooled by diet; one subsample was examined for their ability to respond humorally IHNV and two other subsamples were challenged by intraperitoneal injection with a virulent strain of the same virus. Substituting barely flour for wheat flour in a fish-meal based diet did not substantially alter weight gain or proximate composition of rainbow trout. In contrast, positive effects of barley genotype on disease resistance were observed. Trout fed the average or high '-glucan barley genotypes had survival rates similar to those fed the commercially available challenge. The results indicate that select barley genotypes can be substituted for wheat without significant detrimental effects on production efficiency while potentially increasing resistance to viral pathogens.

Last Modified: 7/23/2014
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