Two feeding experiments were conducted to evaluate if methionine is limiting in practical growout diets for tilapia, Oreochromis spp. Four diets containing 32% protein and 5% lipid were designed to compare the use of diets high in dehulled solvent-extracted soybean meal (DSESM) and expeller-pressed soybean meal (EPSM) as compared to a diet containing 6% fish meal (FM). Tilapia ( ± g, mean ± SD) were randomly stocked into twelve 600-L flow-through tanks at 20 fish per tank. | 186 NGHIÊN CỨU KHOA HOC KY THUAT ĐÁNH GIA VIỆC SỬ DUNG MỘT SO LOẠI ĐẠM ĐỘNG VÁ THựC VÁT ĐE THÁY Thệ bột cá trong kháu phán THỨC ÁN CÁ RỘ PHI Oreochromis spp. EVALUATION OF ALTERNATIVE PROTEIN SOURCES TO REPLACE FISH MEAL IN PRACTICAL DIETS FOR JUVENILE TILAPIA Oreochromis spp. Nguyen Như Trí D. Allen Davis va I. Patrick Saoud Khoa Thuy Sàn Trường Đại hoc Nong Làm . Department of Fisheries and Allied Aquacultures Auburn University Alabama USA. Department of Biology American University of Beiru Beirut Lebanon ABSTRACT Two feeding experiments were conducted to evaluate if methionine is limiting in practical grow-out diets for tilapia Oreochromis spp. Four diets containing 32 protein and 5 lipid were designed to compare the use of diets high in dehulled solvent-extracted soybean meal DSESM and expeller-pressed soybean meal EPSM as compared to a diet containing 6 fish meal FM . Tilapia g mean SD were randomly stocked into twelve 600-L flow-through tanks at 20 fish per tank. After six weeks there were no notable trends or statistically significant differences P in final mean weight survival rate and feed conversion ratio FCR among the treatments. Since results of this study indicated that DSESM could totally replace fish meal in practical diets for juvenile tilapia a second batch of diets were formulated using other protein sources. Typical levels of cottonseed meal CSM DSESM and meat and bone meal MBM were used to evaluate whether methionine could be limiting. Two basal diet formulations were tested either without or with methionine supplement 100g diet . The first diet contained 15 CSM 27 DSESM and 10 MBM and the second diet contained 15 CSM and 37 DSESM. These diets contained 28 protein and 5 lipid. Tilapia g were randomly stocked into twelve 60-L glass aquaria of a recirculation system at 18 fish per aquarium for five weeks and then moved to the 600-L flow-through tanks for five more weeks. After ten weeks there was no .