9 Dispensable amino acids can be synthesized by catfish, but there are certain
advantages if they are provided in the diet. Practical catfish feeds contain liberal amounts of dispensable amino acids inherent in the proteins of various feedstuffs.
Channel catfish have been shown to require the same 10 indispensable amino acids as other fish. The quantitative requirements for these indispensable amino
acids are summarized in Table 2.
Table 2. Amino acid requirement of catfishes Essential
Amino Acid Requirement g kg
-1
protein African Catfish
Channel Catfish Clarias hybrid
Arginine 45
43 17.8-20
Histidine 15
Isoleucine 26
Leucine 35
35 Lysine
57 51
50 48
Methionine +Cystine
32 23
24 Phenylalanine
+Tyrosine 50
Threonine 20
Tryptophan 11
5 Valine
30 Reference
Fagbenro et al. 1999
Wilson et al. 1980 Robinson et al. 1981
Harding et al. 1977 Unprasert
1994
2.3 Amino Acid Supply
The dietary non-essential amino acids supplied in a diet, while not required, help to promote growth by reducing the need for amino acid synthesis, which
saves energy Tucker Robinson 1991. During the digestion process, the rates of release and absorption of amino acids influence the dietary value of a protein
source. Proteins that contain an abundance of indispensable amino acids are
commonly considered high-quality proteins. The radar plot is one of tools which can be used to evaluate the quality of protein. Figure 3 gives examples of radar
plot for good and bad dietary protein content.
10 Figure 3. Dietary with good and bad protein content to satisfy catfish requirement.
From the radar plot above, supply from dietary with bad protein content can not satisfied catfish requirement; while the good protein can satisfied the catfish
requirement, even some amino acids are in excess. Surplus amino acids supply by one protein has no adverse effect on the animal Lloyd et al. 1978. This appears
to be true for most diets composed with natural feedstuffs. If an indispensable amino acid is in excess then it will be catabolised, while if it is deficient the
growth will be limited. Crystalline amino acid supplementation is a way to override amino-acid
deficiency resulting from incorporation of low quality protein in the diet. However, if growth improvements are observed the utilization of such crystalline
amino acid can lead to various problems Halver 1957. Several researchers Yamada et al. 1981, Murai et al. 1987, Schuhmacher et
al. 1993 have demonstrated that amino acid concentrations in blood plasma increased more rapidly, and reached a peak level more quickly, after feeding
crystalline amino acids than after feeding intact proteins. Cowey and Walton 1988, made similar observations when they measured the increase in
radioactivity in the blood of rainbow trout after feeding pellets containing either
14
C-labeled amino acids or
14
C-labeled protein. The lower growth rates and higher feed conversion ratios of rainbow trout fed crystalline amino acids have been
attributed to a rapid uptake of amino acids from the gut into the peripheral blood,
0.0 5.0
10.0 15.0
20.0 25.0
30.0 Lys
Arg His
Ile
Leu Met+Cys
Phe+Tyr Thr
Trp Val
Catfish requirement Good protein
Bad protein
11 leading to the deamination of the amino acids in excess and to higher rate of
nitrogen excretion Yamada et al. 1981, Cowey Walton 1988.
Figure 4. Satisfying catfish requirement by increasing amount of protein bound- lysine.
Faster absorption of free amino acid may lead to transient amino acid imbalances and consequently to decreased protein utilization if crystalline amino
acid is used to supplement dietary protein. Then giving dietary protein bound- lysine must be better than supplementation crystalline lysine to meet requirement
of amino acid. This can be achieved by mixing protein with complementary amino acid profile, or by increasing protein supply in order to provide adequate amount
on absolute basis of the target missing amino acid. Considering the low quality protein example previously, a 59 increase in protein supply may meet catfish
requirement for lysine Figure 4.
5 10
15 20
25 Lys
Arg His
Ile 0.5 Leu
Met+Cys 0.5 Phe+Tyr
Thr Trp
Val Catfish requirement
Bad protein Bad protein + 59
Bad protein + crystalline lysine
III. MATERIALS AND METHODS
3.1 Rearing Condition
The experiment was conducted at Balai Riset Budidaya Ikan Hias BRBIH Depok, West Java with the support of Institut de Recherche pour le
Développement. Fishes
were 3-inch
patin juvenile
Pangasianodon hypophthalmus with an average mass 6.4±0.2 g. Density was 12 fishes per 60 L
for each aquarium 50 cm x 40 cm x 40 cm. These fishes were obtained from Balai Besar Pengembangan Budidaya Air Tawar BBPBAT Sukabumi, West
Java. Before rearing, patin juvenile were being adapted to low fish meal diet
during one week. The experimental period lasted 6 weeks with various daily
protein supplies. Daily ration were given in the 3 equal meals at 08.00, 12.00 and 16.00. Aquariums were cleaned by siphoning every morning before first meal
07.00 am. Fish biomass was recorded every week to adjust daily ration in each aquarium. Prior to sampling, fishes were anesthetized with 600 µL L
-1
eugenol solution 10 in ethanol.
Water quality ammonia-N, pH, O
2
, temperature and conductivity was monitored weekly.
3.2 Diets
Feeds were prepared using fish meal Chile, soybean meal India, corn meal local market, wheat gluten meal Australia, palm oil local grocery, corn
oil, fish oil Aphytec, France, vitamin, mineral Agrobase
®
, France and binder Carboxyl Methyl Cellulose. The formulations were given in below Table 3.
3.3 Chemical Analysis
Chemical analyses were conducted to measure proximate composition of feed ingredients, feeds, fish body and faeces. Proximate of feed ingredients was used as
basis to formulate the diet and so proximate of diet after pelleting to check the composition. Proximate analysis of fish body was conducted at the beginning and
