EFFECT OF IRON-AMINO ACID CHELATE SUPPLEMENTED FISH FEEDS ON GROWTH PERFORMANCE OF NILE TILAPIA Oreochromis niloticus IN AN AQUAPONIC SYSTEM IN KENYA

Kenneth Rono*, Julius O. Manyala, David Lusega, Charles Ngugi, Kevin Fitzsimmons and Hillary Egna
 
University of Eldoret
Department of Fisheries and Aquatic Sciences
P. O. Box 1125, Eldoret, KENYA
manyalajo@yahoo.com
 

Aquaponics is an environmentally friendly production system involving reuse of waste and nutrients in production of fish and vegetables. This study investigated the effect of iron bis-glycine supplement in fish feeds on growth performance of mono-sex Nile tilapia (Oreochromis niloticus) and spinach (Spinacia oleracea) in a small aquaponic system. The study was conducted at the University of Eldoret for 119 days. Complete randomized design was used. Supplementation rates in fish diets constituted 30g Fe kg-1, 20g Fe kg-1, 10g Fe kg-1 and 0g Fe kg-1 respectively. Nile tilapia fry with a mean weight of 0.475 ± 0.025g were stocked in 12 aquaria in an aquaponic system. The 30g Fe kg-1 treatment resulted in the highest fish growth performance with final weights of 11.606 ± 0.55g, an SGR of 2.516 ± 0.01 and a good FCR of 1.10 ± 0.107 compared to the 0g Fe kg-1 treatment that exhibited the lowest mean weight of 4.354 ± 0.295g, an SGR of 1.744 ± 0.02 and a higher FCR of 2.081 ± 0.797. In the carcass composition analysis, 30g Fe kg-1 treatment exhibited a significant difference (p < 0.05) for  higher ash content, crude protein and lower crude lipids (16.350 ± 0.03%, 65.607 ± 0.74% and 12.20 ± 0.256%, respectively) while treatment 0g Fe kg-1 showed lowest ash content, crude protein and crude lipids (10.59 ± 2.12%, 59.671 ± 0.676% and 18.20 ± 0.465% respectively). The hemoglobin and hematocrit levels were higher at 30g Fe kg-1 (45.090 ± 0.704 % and 15.630 ± 0.935g dL-1) and lower at 0g Fe kg-1 treatment (29.773 ± 0.213% and 9.9244 ± 0.071g dL-1). We recorded a decrease in glucose levels with increased supplementation of iron amino acids chelates. The 0g Fe kg-1 demonstrated higher glucose levels (26.8 ± 0.0289mg dL-l) and lower levels at 30g Fe kg-1 (13.433 ± 0.169 mg dL-1). These results revealed that 30g Fe kg-1 iron amino acid chelate supplementation had better nutritional attributes as feedstuff for O. niloticus growth than the two other dietary treatments. Iron amino acid chelate supplementation at appropriate levels of concentration may be desirable in complete diet formulations for enhancement of physiological efficiency and accumulation of body proteins for growth efficiency. The study recommends the incorporation of iron amino acid chelate in on-farm formulated diets where complete diets are not easily accessible for small scale farmers.