Nutritional evaluation of waste date fruit as partial substitute for soybean meal in practical diets of juvenile Nile tilapia, Oreochromis niloticus L.

The potential of waste date meal (WDM; low-quality date palm, Phoenix dactylifera L.) as a carbohydrate source in formulated diets for Nile tilapia was evaluated. Four isocaloric-practical diets (15.7 kJ g(-1)) were formulated incorporating WDM at 0, 100, 200 and 300 g kg(-1) levels as partial substitutes for soybean meal (SBM). These were designated D-0 [284 g crude protein (CP) and 383 g carbohydrate (CHO) kg(-1) diet], D-1 (279 g CP and 446 g CHO kg(-1) diet), D-2 (207 g CP and 495 g CHO kg(-1) diet) and D-3 (175 g CP and 578 g CHO kg(-1) diet). Each diet was fed to three replicate groups of 30 fish [20.20 +/- 0.09 g (+/- SE)] for 75 days. No feed-related mortality was observed during the entire experimental period. Final body weight (FBW) and specific growth rate (SGR) in the different treatments were statistically not significantly different (P > 0.05). Protein efficiency rate (PER) was lowest in diet D-0 and increased with decrease of SBM content (D-1-D-3). A significant increase in whole body lipid content was recorded in fish fed diets D-2 and D-3. Results showed that WDM could be a substitute for SBM up to 300 g kg(-1) in practical Nile tilapia diets without compromising growth.