International Journal of Aquaculture, 2013, Vol.3, No.6, 23
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upon the roughness of the water surface and angle of
radiation. In the maize bran and chicken manure fed
ponds there was low transparency because of stimulation
of algae production from the manure. When secchi
disk visibility is shallower, this reflects a high algal
abundance in the photic zone which is positively
correlated with fish growth and nutrition (Abbas and
Hafeez-Ur-Rehman, 2005). Natural water can never
be pure and contains substances (plankton, debris
etc.) which further interfere with light penetration.
Light exerts a profound influence upon the whole series
of biological phenomenon of water by controlling
the occurrence and abundance of phytoplankton
(
Corpei, 2001).
In aquaculture, the ultimate aim is not to achieve the
highest mean weight (De-Silva et al., 1989), the
emphasis is on a low environmental burden and the
cost effectiveness.
O. niloticus
is considered a prime
species for culture in tropical and subtropical
regions, because it has a fast growth rate and adapts
to a wide range of environmental conditions
(
Marshall, 2010). This could be due to the better
performance and utilization of the diets in spite of
high fibre levels. Comparison of means showed
significant difference in mean weight, specific
growth rate, percentage weight gain and condition
factor between chicken manure, maize bran and the
control pond. Li and Yakupitiyage (2003) reported
that pond fertilization such as organic matter
provides exogenous elementary nutrients that
enhance natural food productivity for omnivorous
fish like
O. niloticus
.
Consequently, depending on
the actual conditions, phytoplankton and zooplankton
may be an important source of nutrients, supplementing
the diets of fish raised in pond culture (Rakocy and
McGinty, 1989; Bentsen et al., 2001). The pond
which had chicken manure applied to it had high
plankton, which fish fed on and led to a high
specific (growth) rate though, maize bran fed fish
grew faster because they consumed the bran directly
when fed. Manure from poultry droppings promotes
natural food webs that improve
O. niloticus
production.
Diana et al. (1994) demonstrated that organic fertilizers
result in higher primary production in lakes and
consequently larger sized algivorous fish.
The standard total length in maize bran pond and
chicken manure pond had a small difference
showing that the weight increased more regardless
of feed and time. During a five-month culture period,
O. niloticus
increased from an initial weight of 13.5 g
to a final weight of 108.7 g in the maize bran treated
pond. In the Philippines, Guerrero (1980) cited in
Beveridge et al. (2002) indicated that diets with 25%
maize bran was economical for cage culture of
O.
niloticus
.
Fish fed on maize bran ponds had
significantly higher mean weight than fish fed
chicken manure and the control. Liti et al (2001)
compared the performance of chicken manure with
commercial fish diet and observed better growth on
O. niloticus
with the chicken manure than with other
fish feeds. Supplemental feeding permits fish to
continue to grow rapidly (Hepher, 1988). Condition
factors increased in week 8 for maize bran and
chicken manure ponds showing that there was a
significant difference in the treatments applied. The
condition factor reflects the physiological state of
the fish in relation to its welfare (Shakir et al., 2008).
In this study, the condition factor and survival rates
were significantly different showing that the
composition and mode of action of the maize
bran and chicken manure were different as we
used the same fish species. The condition factors
of fish in previous studies revealed that 4 fish
species;
C. gariepinus, L. altivelis, O. mossambiccus
and
T. rendalli
had their K values outside the 2.9
-
4.8
recommended range for matured freshwater fish
according to (Bagenal and Tesch, 1978).
The survival rate was highest in the control pond
and least in the chicken manure fed pond, organic
fertilizer particularly the chicken manure used in this
study encourage growth of detrimental microorganisms
during their degradation (Leveque, 2002). However,
the high survival rate of
O.niloticus
at high density
in the control pond and maize bran fed ponds
indicates its amenability to the intensive culture
practice (Pardon, 2001).Chicken manure as a fish
feed is useful because the carbon dioxide released
after decomposition provides the inorganic carbon
needed for photosynthesis or slowly enters the
carbonic acid-bicarbonate-carbonate system that acts
as a pH buffer (Nath, 1993). This buffer is important
in protecting fish and other aquatic organisms from
the adverse effects of pH fluctuations. Parts of the
organic material settle as pond sediments that
significantly contribute towards seepage reduction.
Some benefits of chicken manure fertilization,