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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: The effect of soybean meal processing method and diet inclusion level on growth and intestinal morphology of rainbow trout Onchorynchus mykiss.

Authors
item Barrows, Frederic
item Gaylord, Thomas
item Sealey, Wendy - UNIV OF ID, HAGERMAN
item Haas, Michael - ERRC WYNDMOOR, PA
item Stroup, Robert - RL STOUP CO LTD OHIO

Submitted to: World Aquaculture Society Meeting
Publication Type: Abstract Only
Publication Acceptance Date: January 16, 2007
Publication Date: May 1, 2007
Repository URL: http://riley.nal.usda.gov/nal_web/digi/submission.html
Citation: Barrows, F., Gaylord, T.G., Sealey, W.M., Haas, M.J., Stroup, R.L. 2007. The effect of soybean meal processing method and diet inclusion level on growth and intestinal morphology of rainbow trout Onchorynchus mykiss.. World Aquaculture Society Meeting.

Interpretive Summary: Standard soybean meal is produced by toasting to reduce trypsin inhibitor levels and hexane extraction to remove the valuable soybean oil. The extracted oil is used primarily in human foods, with its use as a feedstock for production of biodiesel, a replacement for conventional petroleum diesel fuel, presently growing rapidly. A new method for soybean meal processing has been developed, with the goal of making soy oil a more economical source for the production of biodiesel. This method, ‘in situ transesterification’ is a one step process for biodiesel production. If the resulting meal is comparable in nutritional value to commercially available solvent extracted soybean meal (SE-SBM) the new process could become widely used in the bio-fuel industry. Rainbow trout were fed soybean meals produced using the different processes. After 9 weeks of feeding the experimental diets fish had gained on average over 600% body weight. There was no effect of soybean meal processing method on weight gain.

Technical Abstract: Standard soybean meal is produced by toasting to reduce trypsin inhibitor levels and hexane extraction to remove the valuable soybean oil. The extracted oil is used primarily in human foods, with its use as a feedstock for production of biodiesel, a replacement for conventional petroleum diesel fuel, presently growing rapidly. A new method for soybean meal processing has been developed, with the goal of making soy oil a more economical source for the production of biodiesel. This method, ‘in situ transesterification’ eliminates hexane extraction to remove the oil, combining the extraction and transesterification steps into one process for biodiesel production. If the resulting meal is comparable in nutritional value to commercially available solvent extracted soybean meal (SE-SBM) the new process could become widely used in the bio-fuel industry. Two levels of each of three types of soybean meal were fed to triplicate lots of 30 (initial wt 22g.) rainbow trout for 9 weeks in flow-through 15oC spring water. The inclusion levels of 17.5 and 35% SBM were chosen to be above and below the generally regarded threshold of growth reduction of 20% for SE-SBM. The three types of soybean meal included SE-SBM, experimentally produced SE-SBM (ESE-SBM), and meal produced using in-situ transesterfication (IS-SBM) and were each fed at two levels for a total of 6 diets. Growth rate of fish fed any of the diets was good, averaging over 600% gain. There was no effect of type of soybean meal on weight gain of trout. The fish fed the meal processed by the new method gained as much weight as either of the two control meals. The fish fed the diets containing IS-SBM, however, did have higher feed intakes (2.51% bw/d) as compared to fish fed the ESE-SBM or SE-SBM, 2.38 and 2.46% bw/d, respectively. Since growth rate was equal, feed conversion ratios were higher for the fish fed the IS-SBM. Protein and energy retention values were lower for the fish fed the IS-SBM diets. There was no effect of soybean source on carcass composition. The effect of diet on apparent nutrient digestibility coefficients and apparent amino acid availabilities will be presented. The presence of large numbers of gram-positive bacteria in the intestinal tracts of fish from all diet groups was observed. Only minor effects of these bacteria were observed, but typical soybean enteritis was not observed. Within the conditions of this study, fish fed the soybean meal produced using the new method had growth equal to trout fed SE-SBM.

Last Modified: 9/1/2014
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