A 12-week feeding trial was conducted to estimate
the dietary copper requirement of fingerling Channa
punctatus. Six caseingelatin-based test diets
(450 g kg
1 crude protein; 18.81 kJ g
1 gross
energy) with graded levels of copper as copper sulphate
(3.7, 4.7, 5.7, 6.7, 7.7 and 8.7 mg copper
equivalent kg
1 diet) were formulated and fed to
triplicate groups of fish (7.25 0.81 cm; 5.21
0.27 g) near to satiation. Fish fed diet with 6.7 mg
kg
1 copper had highest absolute weight gain
(AWG; 51.63 g fish
1), protein efficiency ratio
(PER; 1.42 g fish
1), protein gain (PG; 8.34 g
fish
1), haemoglobin (Hb; 9.68 g dL
1), haematocrit
(Hct; 31.18%) and RBCs (3.24 9 106 9 mm
3).
Feed conversion ratio (FCR) was found to be best
(1.57) at above level of dietary copper. Whole body
copper concentration was found to increase with
the increasing levels of dietary copper. Hepatic
thiobarbituric acid-reactive substances concentration
was found to decrease with increasing dietary
concentrations of copper up to 6.7 mg kg
1 beyond
which a reverse trend in this parameter was noted.
Broken-line regression analysis of AWG, FCR and
PG concentrations against varying levels of dietary
copper yielded the requirement in the range of
6.66–6.78 mg kg
1. Data generated during this
study would be useful in formulating copperbalanced
commercial feeds for the intensive culture
of this fish. |
