Abstract:
Azolla is a potential fish feed ingredient due to its high nutritional value, abundant
production and low cost of production. This study investigated the replacement of
protein sources with azolla in fish feed formulation, using Genetically Improved
Farm Tilapia (GIFT) as a model to assess growth performances and cost effectiveness. A commercial feed was used as a positive control (PC). Iso-protein
feed was prepared, supplementing the negative control (NC) of 0% azolla with 15%
(T1), 20% (T2), and 25% (T3) of Azolla. The feed was prepared using air-dried
Azolla powder. Tilapia fingerlings (body weight: 1.72±0.09 g) were stocked in fifteen
rectangular tanks (60 cm× 30 cm× 30 cm). Three replicates were conducted per
treatment, each comprising 15 fingerlings. They were fed with the treatments for 45
days. The proximate compositions, quality parameters of feeds and growth
parameters of the fingerlings were analyzed by using ANOVA. The color and water
stability of the feeds were significantly different (p<0.05) while PC had better
quality parameters. Water quality parameters; pH (6.6-7.5), salinity (0.51-0.56
PSU), temperature (26-28°C), and nitrate nitrogen (1.9-2.9 mg L-1
) of all fish tanks
reported within acceptable levels. Nevertheless, there was a significant difference
(p<0.05) in turbidity among the treatments, and the higher the azolla percentage,
the turbidity level increased from 3.8 to 8.5 NTU. Weight gain (WG), length gain
(LG), and specific growth rate (SGR) were significantly different among the
treatments while PC had the highest WG (475.06±2.11%), LG (61.54±1.61%), and
SGR (2.02±0.02% day-1
). Among the formulated feeds, the significantly highest
SGR (1.92±0.07% day-1
) was observed in T3. Among the treatments, survival rates
were insignificant (p>0.05) and T3 exhibited a significantly lower (p<0.05)
incidence cost. Therefore, it can be concluded that incorporating 25% azolla (T3)
in GIFT tilapia feed could achieve a higher specific growth rate while saving on
feed cost.
