Three leaf meals,
Gliricidia sepium
, cassava (
Manihot esculenta
), and
Stylosanthes humilis
were screened as feed supplements in the culture of the Nile Tilapia,
Oreochromis niloticus
. The experiment had four treatments. Treatment A had
S.
humilis leaf meal incorporated in the feed while treatment B had cassava leaf meal in
the feed. Treatment C had
Gliricidia leaf meal incorporated in the feed while
treatment D was made up of feed formulated without leaf meal (control). Proximate
analysis of these leaf meals showed that Cassava leaf meal had the highest crude
protein content (26.3%) followed by
Gliricidia leaf meal (22.9%) and
Stylosanthes
leaf meal (19.5%). All the four diets (A – D) were formulated with maize flour,
soybean, fish meal, blood meal and the respective leaf meals and crude protein
content ranged from 30.57 – 36.42 %. The diets were distributed randomly to twelve
experimental units containing
Oreochromis niloticus fingerlings with mean weight
range of 2.40-2.55g and fed for twelve weeks. The feed containing cassava leaf meal
(Treatment B) gave the best mean weight gain of 3.50 ± 0.01g followed by the feed
with
Gliricidia leaf meal with a mean weight gain of 2.21 ± 0.06g while the feed with
Stylosanthes leaf meal and the control gave mean weight gains of 2.05 ± 0.25g and
1.06 ± 0.03g, respectively. Mean weight gain in treatment B (cassava leaves) was
significantly higher (P < 0.05) than mean weight gain in other treatments. Mean growth
rate ranged from 0.01 ± 0.006 g/day for the control treatment to 0.04 ± 0.001 for the
fish fed Cassava leaf meal diet. Specific growth rate (SGR) was also highest in the
treatment with cassava leaf meal (1.07 ± 0.11%/day) and lowest in the control. Protein
efficiency ratio (PER) was 0.11 ± 0.004 in Treatment B, 0.07 ± 0.001 in Treatment C,
0.06 ± 0.009 in Treatment A and 0.03 ± 0.001 in the control. The food conversion
ratio (FCR) was best with cassava leaf feed (3.71 ± 0.19) followed by
Stylosanthes
(5.51 ± 0.27),
Glyricidia (6.17 ± 0.22) and the control (9.48 ± 0.58). FCR, SGR and
PER for treatment B (cassava leaves) were significantly better (P < 0.05) than the
values for other treatments. Percentage survival ranged from 92% with
Stylosanthes to
100% with cassava leaf feed. The study showed that leaf meals can be effectively
used in the diet of
Oreochromis niloticus.
