The Israeli Journal of Aquaculture - Bamidgeh 62(3), 2010, 163-171 Effects of Extruded Red Lentil Meal on Growth Performance, Nutrient Digestibility, and Dorsal Muscle Composition in Rainbow Trout (Oncorhynchus mykiss) Zehra Selcuk 1 , Serap Ustaoglu Tiril 2 , Fikret Alagil 2 , Mustafa Salman 1 , Omer Hakan Muglali 1 1 Department of Animal Nutrition and Nutritional Diseases, Faculty of Veterinary Medicine, Ondokuz Mayis University, Kurupelit 55139, Samsun, Turkey 2 Fisheries Faculty, Sinop University, 57000, Sinop, Turkey (Received 25.8.09, Accepted 29.9.09) Key words: extruded red lentil meal, growth performance, nutrient digestibility, rainbow trout Abstract The aim of this study was to evaluate the inclusion of extruded red lentil meal as a plant protein source in a rainbow trout diet. Rainbow trout (n = 207) were randomly allocated to the control and two treatment groups. Diets were isonitrogenous and isocaloric. The control diet contained no extruded red lentil meal. Fish in treatments 1 and 2 were fed diets containing 10% and 15% extruded red lentil meal, respectively. Fish were fed twice a day to apparent satiation for 84 days. There were no significant (p>0.05) differences in weight gain, feed conversion ratio, protein efficiency ratio, dorsal muscle composition, or survival. Digestibility of nitrogen free extract+crude fiber was higher in the experimental groups than in the control. Thus, extruded red lentil meal can be considered as a protein source for rainbow trout diets up to the level of 15%.  Corresponding author. Tel.: +90-362-3121919/3893, fax: +90-362-4576922, e-mail: zselcuk@omu.edu.tr The IJA appears now exclusively as a peer- reviewed on-line Open Access journal at http://www.siamb.org.il