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

Abstract

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 D0 [284 g crude protein (CP) and 383 g carbohydrate (CHO) kg−1 diet], D1 (279 g CP and 446 g CHO kg−1 diet), D2 (207 g CP and 495 g CHO kg−1 diet) and D3 (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 D0 and increased with decrease of SBM content (D1–D3). A significant increase in whole body lipid content was recorded in fish fed diets D2 and D3. Results showed that WDM could be a substitute for SBM up to 300 g kg−1 in practical Nile tilapia diets without compromising growth.