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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 Title: Apparent digestibility of nutrients in extruded diets from cultivars of barley and wheat selected for nutritional quality in rainbow trout Oncorhynchus mykiss

Authors
item Gaylord, Thomas
item Barrows, Frederic
item Rawles, Steven
item Liu, Keshun
item Bregitzer, Phil
item Hang, An - RETIRED USDA ARS ABERDEEN
item Obert, Donald
item Morris, Craig

Submitted to: Aquaculture Nutrition
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: April 16, 2008
Publication Date: June 15, 2009
Repository URL: http://riley.nal.usda.gov/nal_web/digi/submission.html
Citation: Gaylord, T.G., Barrows, F., Rawles, S.D., Liu, K., Bregitzer, P.P., Hang, A., Obert, D.E., Morris, C.F. 2009. Apparent digestibility of nutrients in extruded diets from cultivars of barley and wheat selected for nutritional quality in rainbow trout Oncorhynchus mykiss. Aquaculture Nutrition. 15:306-312.

Interpretive Summary: "Apparent digestibility of nutrients in extruded diets from cultivars of barley and wheat selected for nutritional quality in rainbow trout Oncorhynchus mykiss" In order to screen for the nutritional value of barley (Hordeum vulgare L.) lines with potential for aquafeeds, one must first quantify the digestibility of nutrients in these ingredients. A digestibility trial was conducted to elucidate potential differences in barley lines and varieties with potential for use in aquafeeds. A diverse group of six barley lines having six combinations of selected attributes, normal vs. low phytic acid, normal vs. waxy, and hulled vs. hulless, were chosen along with a waxy wheat(Triticum aestivum L.) and soft white wheat. Apparent digestibility coefficients of the eight ingredients were determined for rainbow trout with diets manufactured by cooking extrusion. Phosphorus availability ranged from 17 to 78% and was influenced by starch type in wheat. Apparent protein digestibility ranged from 53 to 125% and differences were observed in wheat varieties based on starch type. Apparent energy digestibility ranged from 32 to 63%, with waxy barley varieties having higher energy digestibility coefficients than normal starch varieties. Waxy starch varieties had higher starch digestibility in both barley and wheat due to the greater digestibility of amylopectin than amylose. Thus, the data indicates that waxy varieties of barley have higher energy digestibility than normal starch type barleys, and waxy varieties warrant further attention as feed ingredients for rainbow trout.

Technical Abstract: "Apparent digestibility of nutrients in extruded diets from cultivars of barley and wheat selected for nutritional quality in rainbow trout Oncorhynchus mykiss" In order to screen for the nutritional value of barley (Hordeum vulgare L.) lines with potential for aquafeeds, one must first quantify the digestibility of nutrients in these ingredients. A digestibility trial was conducted to elucidate potential differences in barley lines and varieties with potential for use in aquafeeds. A diverse group of six barley lines having six combinations of selected attributes, normal vs. low phytic acid, normal vs. waxy, and hulled vs. hulless, were chosen along with a waxy wheat(Triticum aestivum L.) and soft white wheat. Apparent digestibility coefficients of the eight ingredients were determined with triplicate tanks of 50, 250 g rainbow trout. The experimental diets were manufactured by cooking extrusion (Buhler DNDL-44) and consisted of 70% reference diet that was formulated to contain a minimal level of phosphorus and 30% test ingredient. Diets were fed to triplicate groups of fish. Phosphorus availability ranged from 17 to 78% and was influenced by starch type in wheat. Apparent protein digestibility ranged from 53 to 125% and differences were observed in wheat varieties based on starch type. Apparent energy digestibility ranged from 32 to 63%, with waxy barley varieties having higher energy digestibility coefficients than normal starch varieties. Waxy starch varieties had higher starch digestibility in both barley and wheat due to the greater digestibility of amylopectin than amylose. Thus, the data indicates that waxy varieties of barley have higher energy digestibility than normal starch type barleys, and waxy varieties warrant further attention as feed ingredients for rainbow trout.

Last Modified: 10/23/2014
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