The effect of feed mixtures with different protein and fat contents on production and chemical composition of the body of juvenile African catfish (Clarias gariepinus)
R. Ondra et J. Jirasek, The effect of feed mixtures with different protein and fat contents on production and chemical composition of the body of juvenile African catfish (Clarias gariepinus), CZEC J ANIM, 45(6), 2000, pp. 277-284
The African catfish Clarias gariepinus (Burchell, 1822) is considered as th
e most suitable species for intensive aquaculture in lukewarm waters due to
its physiological characteristics and delicious meat. The objective of the
paper was to compare the effect of available feeds for the culture of trou
t, catfish and carp on the growth rate and resultant chemical composition o
f the body in African catfish. The first experiment was conducted to test t
wo feeds with different contents of proteins and fat (PA2 - declared nutrie
nt content 47% proteins/12.5% fat, SA2 - 49/14) in fish with two initial we
ights (12.5 and 20.2 g). The performance parameters were positively influen
ced by feed with higher protein and fat content (SA2). The values of specif
ic growth rate in experimental fish of both weight categories receiving thi
s feed were higher in the first stage (20 days) by 2.3% (fish with lower in
itial weight - 3.06%/d) and by 2.9% (fish with higher initial weight - 3.86
%/d) than in the other group (SGR 2.99 and 3.75%/d). But the differences in
fish growth rate were not statistically significant. A similar trend was o
bserved in the second stage of experiment (22 days). The use of feeds with
higher protein and fat content (SA2) resulted in an increase in hepatosomat
ic index (HSI) in both smaller and larger fish (by 40.1% and 10.6%, respect
ively) in the first stage of experiment and in higher fat deposition in mus
cle (by 13.3 and 28.5%, resp,) at the end of experiment. The second experim
ent was carried out to test feeds for the production of trout (P2 - 42/13),
catfish (S2 - 42/10) and carp (K2 - 30/14) in fish with initial weight 76.
2 g. In the first stage of experiment (35 days), the best results were dete
rmined in fish receiving feed S2 (42/10 - SGR 1.44%/d, FCR 1.04), the worst
in fish on diet K2 (30/14 - SGR 0.56%/d, FCR 3.32). Average individual wei
ght of fish receiving feed K2 was demonstrably lower than in the other vari
ants (P < 0.01) and was accompanied by the largest decrease in deposition o
f intramuscular fat (by 38.7% in females, by 29.6% in males) and visceral f
at (by 60.6% in males, by 51.3% in females) in comparison with the values d
etermined at the beginning of experiment. Tn the second stage of experiment
(35 days), slower growth rate and lower feed conversion ratio were observe
d in the first (S2) and in the second variant (P2) while these parameters h
ad higher values in the third variant when feed K2 was replaced by feed S2.
The lower feeding intensity (1.5% of fish weight) resulted in further decr
ease in fat deposition and adipose tissue proportion in fish viscera in all
variants.