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Effect of graded levels of
phosphorus on growth and mineral concentration in giant
African catfish Heterobranchus bidorsalis
L. C. Nwanna1*, I. A. Adebayo2 and
B. Omitoyin3
1Department
of Fisheries and Wildlife, Federal University of Technology,
P. M. B. 704 Akure, Nigeria.
2Faculty
of Agriculture, University of Ado Ekiti, Nigeria.
3Department
of Wildlife and Fisheries MGT. University of Ibadan,
Nigeria.
*Corresponding author.
E-mail:
drlu2001@yahoo.com.
Tel: 234/8033582428.
Accepted 20
March, 2009 |
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Eleven diets (D1 - D11), designated as treatments (T1 - T11),
supplemented with different levels of inorganic phosphorus
(P) (CaHPO4) were fed to Heterobranchus
bidorsalis (10.8
± 0.02 g) to determine the optimum P requirement. D1 - D11
contained total P of 10.2, 10.4, 11.0, 11.9, 12.3, 12.6,
13.4, 13.9, 14.2 14.7 and 15.4 g kg-1
respectively. After 84 days of feeding trial, there was
increase in fish growth up to T5 with 12.3 g P kg-1
diet, followed by consistent decline in growth towards T11
with the highest P content. However, fish in T5 had the best
(P < 0.05) growth performance and feed conversion ratio (FCR).
Fish in T1 and T2 had the highest (P < 0.05) FCR. Carcass
protein was the same in T5, T6, T7, T8, T9 and T10, which
was higher (P < 0.05) than in T1, T2, T3 and T4. Carcass fat
content was highest in fish in T1 which also had the lowest
water content. P and Ca concentration in fish carcass
increased linearly and was highest (P < 0.05) in fish in
T11, while Mg and Zn were highest (P < 0.05) in fish in T5.
Data from the study suggest 12.3 g P kg-1 diet as
optimum requirement for the growth of
Heterobranchus bidorsalis.
Key
words:
Phosphorus requirement, giant
African
catfish, Heterobranchus bidorsalis. |
