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International Journal of Aquaculture, 2014, Vol.4, No.15 89
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4.5 Determination of Acid Insoluble Ash (AIA) and
apparent digestibility coefficient
Acid Insoluble Ash (AIA) was obtained by adding
25ml of 10% HCl to known weights of the ash
contents of the feed and fish feaces, covered with a
wash glass and boiled gently over low flame for five
minutes, after which it was filtered through ash less
filter paper and washed with, hot distilled water. The
residue from the filter paper was returned into the
crucible and ignited until it was carbon free and it was
re-weighed
% AIA = [(Weight of Ash- Weight of AIA) ×100] /
Weight of Ash.
Apparent Digestibility coefficient (ADC) was
calculated as.
ADC = 100-100 * (% AIA in feeds x % nutrient in
feaces) / (%AIA in feaces % in nutrient in feed).
4.6 Determination of the minerals
Ten grammes (10g) of fish sample were ashed (dry
ashing) at 550
℃
for 6 hours in an electric muffle
furnace; the ashed sample was diluted in 5ml of 10%
HCl. This was filtered and made up to the mark in
50ml volumetric flask, the filtrate was used for the
analysis and this was carried out at the Chemistry
Laboratory of Federal University of Technology,
Akure with the use of an electronic machine-Atomic
absorption/emission spectrophotometer Buck scientific,
model 200-A. The minerals such as Calcium,
Magnesium, Zinc, Iron and Manganese with
wavelength 422nm, 285nm, 214nm, 248nm and
279nm were determined respectively in duplicate
and the average of the result was found. The
absorbance was read off the digital display of the
spectrophotometer. The concentration in parts par
million (ppm) was calculated by.
ppm=R*X*V / W
Where,
R = value of each mineral, W = weight of sample, V =
volume of digested sample used. However, R was
calculated with the use of the formula:
R = (10ppm ×Sample read) / Standard
4.7 Phosphorus
Phosphorus was determined by the use of the UV
visible spectrometer. Ten grammes (10g) were ashed
(dry ashing) at 550
℃
for 6 hours I an electric muffle
furnace, the ashed sample was diluted in 5ml of
10%HCL. The was filtered and made up to the mark
in 50ml volumetric flask, the filtrate was used for the
analysis and this was carried out in Fisheries and
Aquaculture Technology Laboratory, Federal University
of Technology, Akure. The wavelength of the
phosphorus was 440nm and the standard (stock)
solution of the element was prepared and introduced
into the instrument. A solution of the sample is then
introduced and the readings recorded in duplicate and
the average result was found. The concentration in
parts per million was calculated by.
A*V*D / Wt.
Where, A = value of each mineral, Wt = weight of
sample, V = volume of digested sample used.
4.8 Analytical methods
Apparent digestibility coefficient (protein, gross
energy and lipid), mineral composition of fish and
faecal were analyzed after the experiment according to
the methods of A.O.A.C (2005).
4.9 Statistical analysis
Data resulting from the experiment was subjected to
one-way analysis of variance (ANOVA) using SPSS
(Statistical Package for Social Sciences 2006 version
15.0). Duncan multiple range test was used to
compare differences among individual means.
Authors’ contributions
This work was carried out by two authors; NLC and OSE.
Author NLC conceived the idea; NLC and OSE designed the
study and wrote the protocol, author NLC supervised the study.
Author OSE performed the experiment and the statistical
analysis as well as managed the literature searches. Also,
Author OSE wrote the first draft of the manuscript. All authors
read and approved the final manuscript.
Acknowledgements
We are grateful to OJUOLA Michael for his technical support
during the research.
References
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of exogenous enzymes (phytase, non-starch polysaccharide enzyme) in
diets on growth, feed utilisation, nitrogen and phosphorus excretion of
Japanese sea bass,
Lateolabrax japonicas
. Comparative Biochemistry
and Physiology 147: 502–508
Asgard T., and Shearer K.D., 1997, Dietary phosphorus requirement of
juvenile Atlantic salmon,
Salmo salar
L. Aquaculture Nutrition