Alternative plant protein sources are generally cheaper compared to animal protein sources and may be the solution to reduce the high dependence of farmers on fish meal due to the limited world supplies and increasing price of fishmeal. This study focuses on growth performance of Nile Tilapia (Oreochromisniloticus); its gastric evacuation rate and carcass composition when fed with fresh aquatic plant and artificial diet.
Azollapinnata and artificial diet (control) were fed at 3% body weight of 90 Oreochromisniloticus weighing 24±1.43g for 56 days (8 weeks) in three treatments T1(artificial diet), T2 (artificial diet 50% and aquatic plant 50%) and T3 (aquatic plant); each having three replicates. Specific Growth Rate (SGR), Food Conversion Ratio (FCR), Protein Efficiency Ratio (PER), Mean Weight Gain (MWG), Protein Intake (PI) and Length-Weight Relationship were used to determine the growth performance and feed utilization. The serial slaughter method was used to determine Gastric Evacuation Rate (GER) and Gastric Transit Time (GTT). Proximate composition of fish carcass was determined using standard methods. Data were analysed using Descriptive analysis and ANOVA at α0.05.
Fish fed both artificial diet and aquatic plant T2 attained a significantly higher MGW and SGR, and attained the best correlation coefficient value which indicates a good relationship between length and weight. T1 and T2 showed no significant difference in FCR but were significantly lower than T3. The PER showed that T2 was significantly higher than T1 and T3. Duncan’s test of significance indicated that there was no significant difference in the daily feeding rate and GER of Oreocromisniloticus across the treatments but GTT differed in T3. Fish fed only Azolla, T3 had a GTT of 3 hours where as T1 and T2 was 4 hours. Carcass proximate analysis showed that crude protein of T3 was significantly higher than T1. Fat content of T3 was significantly higher than those of T1 and T2.
Oreohchromisniloticus performed better when fed with both artificial diet and aquatic plant, it also attained a higher crude protein level and lower moisture content when fed only aquatic plant compared to those fed only artificial diet.
Key words: Oreohchromisniloticus, utlilization of aquatic plant, growth performance, gastric evacuation, carcass composition.