Effects of Niger Cake Inclusion in Fish Feed as a Major Protein Source on Anion Dynamics in Nile Tilapia-Lettuce Aquaponics System
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Date
2018-05-04
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Addis Ababa University
Abstract
The aquaponics systems culture different organisms that are dependent on nutrients generated from
feed. Most of the time the major protein source of this system is fish meal. However, the
availability of fish meal is very scarce and the cost is not affordable for developing countries. So,
this study was carried out to examine Niger seed cake as replacement of fish meal and also to
compare the anion dynamics of Niger seed cake with fish meal. The experiment was conducted in
five treatments, each treatment in duplicate, with the proportion of Niger seed cake; 0% (Control),
12.5% (TA), 25% (TB), 37.5% (TC), 42.5% (TD). Also a hydroponic treatment (H) was included
to examine performance of each treatment on anion dynamics. Samples of fish, lettuce and water
were collected every week for about five weeks. Both phosphorus and nitrogen groups (ammonia,
nitrite and nitrate) were analyzed by spectrophotometer. The result of the experiment had shown
that as the Niger seed cake inclusion increased in the fish feed (43%), TD, the increment of anion
in the system was observed, which was comparable with the control diet. However, it had low
anion loading than the hydroponic solution. In the lettuce, as percentage of the alternative feed
increased, the concentration of anion became higher and comparable with the control fish feed. In
general, the result of the experiment had shown little difference with the fish meal. Therefore,
higher percentage of alternative feed from plant sources such as Niger seed cake could be taken as
supplementary source of feed.
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Keywords
Anion Dynamics, Aquaculture, Aquaponics, Fish Meal, Hydroponics, Lettuce, Niger Seed Cake, Nile Tilapia