In the both species, the fish fed diets deficient in each of alanine, aspartic acid, cystine, glutamic acid, glycine, proline, and tyrosine grew as well as those fed the complete amino a
Trang 1Bulletin of the Japanese Society of Scientific Fisheries 38(7) 753-759 (1972)
Amino Acids Essential for the Growth of Eels,
Anguilla anguilla and A japonica*
Shigeru ARAI**, Takeshi NOSE**, and Yoshiro HASHIMOTO***
(Received December 28, 1971)
Essential amino acids for the 2 species of eel, A anguilla and A japonica, were examined
by using an amino acid test diet Forty fish were grouped in each aquarium and fed the test diets for a period of 6 weeks In the both species, the fish fed diets deficient in each of alanine, aspartic acid, cystine, glutamic acid, glycine, proline, and tyrosine grew as well as those fed the complete amino acid diet The fish fed diets deficient in each of arginine, histidine, isoleucine, leucine, lysine methionine, phenylalanine, threonine, tryptophan, and valine failed to grow until the deleted amino acid was added to the ration It was thus established that eels require the same 10 kinds of amino acid reported to be essential for salmonids and others.
Ten amino acids have been shown to be essential for the growth of chinook salmon1), sockeye salmon 2) , rainbow trout3), and channel catfish 4) by HALVEDR and his colleagues with amino acid test diets By examining the incorporation of 14 C into amino acids after intraperitoneal injection of [U-14C] glucose, COEEY et al.5) indicated that the plaice and sole have a dietary requirement for amino acids similar to that of salmonids and channel catfish
In the previous paper6), one of the authors reported that methionine, threonine, tryp-tophan and valine were found to be essential and proline to be non-essential for the growth
of the Japanese eel, Anguilla japonica by using the amino acid test diet developed by HAL-VER7) for salmonids The results, however, were not so conclusive, since the test diet itself was not so satisfactory for the growth of eels This led us to study both the test diet and feeding technique for eels and establish a far more reliable testing method8) By using
it, we examined the amino acids essential for the growth of 2 species of eels, A anguilla and A Japonica The results obtained clearly demonstrated that the both species of eel require the same 10 kinds of amino acid as reported on the other fishes.
Materials and Methods
Experimental fish Elvers of A Japonica were obtained in March 1971, from Kago-shima Prefectural Fisheries Station and those of A anguilla in April 1971, from a wholesale
*Contribution of Freshwater Fisheries Research Laboratory
, No, 294.
** Freshwater Fisheries Research Laboratory, 399, Miya, Hina-shi, Tokyo (新 井 茂 ・能 勢 健 嗣:
淡 水 区 水 産 研 究 所).
***Laboratory of Marine Biochemistry
, Faculty of Agriculture, the University of Tokyo, Bunkyo-ku,
Trang 2dealer of freshwater live fish They were kept in tanks at 25•Ž on Tubifex, beef liver and purified casein-gelatin diet8) in order The body weight at the start of feeding eiperi-ment was approximately 1.7 g in A japonica and 0.6 g in A anguilla
Feeding and testing methods Experimental fish were kept in aquariums (20•~20•~
50 cm) made of polyvinyl chloride and well water heated to 25•Ž was supplied after aeration to each aquarium at the rate of 0.4-0.7 liter per minute Before feeding the test diets, they were kept for 2 weeks on a casein-amino acid mixture diet, in which the protein source of the casein-gelatin diet was replaced with a mixture of each nearly equal amount of casein and acid-hydrolyzates of soybean, a product of Ajinomoto Co Ltd and carboxymethylcellulose was used as a binder The other ingredients were not modi-fied practically In addition, A anguilla received the basal diet in Table 1 for 3 days immediately before the start of feeding experiments, but this preliminary feeding with the basal diet was omitted in the case of A japonica The experimental period was 6 weeks for the both eels Each individual was weighed to the nearest 0.01 g after being anes-thetized in a urethane solution (1.2 %, w/v) at intervals of 2 weeks Forty fish were grouped
in each aquarium for each experimental diet Fish were fed twice a day except Sunday and Saturday when they were fed once a day The pasty test diet was extruded into tank
as moist fine noodle from a 50-ml nylon syringe without needle This made eels easy to eat the diet with reduced loss of it Thirty minutes after feeding, the remainder of the diet was siphoned out at each time
Test diet The newly established test diet9) was used as the basal diet after modifi-cation by replacing casein and gelatin with amino acid mixture, adding carboxymethyl-cellulose as a binder, and leaving other ingredients untouched (Table 1) The composi-tion of amino acid mixture simulated that of the beef liver which sustained the excellent growth of eels in the previous work8) and differed only slightly from that of the amino
Table 1 Composition of the basal diet.
* L-arginine.HC1 4.0, L-histidine HCI-H20 2.0, isoleucine 4.0, leucine 6.0, L-lysine HCI 5.0, L-methionine 2.0, L-phenylalanine 3.5, L-threonine 3.0, L-tryptophan 1.0, L-valine 4.5, L-alanine 4.5, L-aspartic acid , 7.5, L-cystine 1.0, L-glutamic acid 10.0, glycine 5.0, L-proline 4.0, and L-tyrosine 3.0 g
** U S.P XII Salt Mixture No 2 with trace metals91
*** Vitaminized cellulose powder The amounts of vitamins added to the diet were same as those reported by HALVER91
Trang 3acid test diet adopted for salmonids and channel catfish Test diets were prepared by deleting a single amino acid from the basal diet by replacing it with a-cellulose powder The diet was finally adjusted to pH 6.2-6.5 with 25 % NaOH.
Results
The average body weight at each weighing period and mortality are summarized in Table 2 for A anguilla and in Table 3 for A japonica
Anguilla anguilla The experiment was conducted from June 6 to July 20, 1971 The fish on the diets deficient in each of arginine, histidine, isoleucine; leucine, lysine, methionine, phenylalanine, threonine, tryptophan and valine showed a loss of appetite
in 3 days and apparent loss of body weight at the end of 2 weeks Mortality was observed
in some groups, especially in the lysine- and valine-deficient ones As shown in Fig 1,
Fig 1 Growth of the experimental fish, A anguilla (-0-; amino acid-deficient diet, -•œ-; complete diet).
the detrimental effects of depletion of some amino acids were apparent at the end of 4 weeks, and to all the groups of fish showing a retarded growth was then given the basal diet for 2 weeks In the recovery test, the fish recovered their normal appetite within
3 days and showed a rapid growth The percent body weight gain ranged from 19 to 49
in the 2-week recovery period These results clearly indicate that A anguilla requires 10 amino acids, arginine, histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan and valine as essential for the normal growth On the other hand, the eels receiving diets lacking each of alanine, aspartic acid, cystine, glutamic acid, glycine, proline and tyrosine showed a growth comparable to that of fish on the basal diet, indicat-ing that these amino acids are dispensable
Trang 4Table2 The growth of eel, Anguilla anguilla, on amino acid test diets.
* Confidence limit (95%)
** Figures in the parentheses show the percent gain in 2 weeks.
Trang 5Table3 The growth of eel, Anguilla japonica, on amino acid test diets.
* Confidence limit (95%)
** Figures in the parentheses show the percent gain in 2 weeks
Trang 6Anguilla japonica The experiment was conducted from July 27 to September 6,
1971 As shown in Fig 2, the growth of eels was generally slow in the first 2-week period, but much improved in the second 2-week period, probably due to acclimation to the amino acid test diet As mentioned above, the preliminary feeding with the basal diet was
omitt-ed in this case The eels kept on the diets deficient in each of arginine, histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan and valine showed a
Fig 2 Growth of the experimental fish, A japonica (-0-; amino acid-deficient diet ,
complete diet).
remarkable loss of their body weight The percent body weight loss ranged from 8 to
15 % for the first 2-week period and 6 to 12 % for the second period In the recovery test lasting for 2-weeks, the fish recovered their appetite within 3 days as in the case of A anguilla, and the percent increase of body weight was 19-32 % in the recovery, test These results clearly demonstrate that there is no difference in essential amino acids between
A japonica and A anguilla.
Discussion
By using the newly established testing method, the amino acids essential for the growth of 2 species of eel, A anguilla and A japonica, were clearly revealed to be the same
as required by salmonids and channel catfish It may be noteworthy that eels seem to
be much more sensitive to the lack of essential amino acids A loss of appetite was recognized in a period as short as 3 days, while in 2 weeks on salmonids1-3) and channel catfish4) The recovery of appetite in the deficient eels was also rapid, when the deleting essential amino acid was added to the ration.
Trang 7Although serine and hydroxyproline were not included in the basal diet, the eels attained nearly the same growth rate on it as on the casein-gelatin diet These 2 amino acids are therefore reasonably classified as dispensable for eels In the previous worek6), the eels receiving the glycine-deficient diet showed a growth apparently inferior to that of the control In this experiment, however, dispensability of glycine was clearly demon-strated in the both species
Acknowledgement
This study was partly supported by a grant from the Ministry of Education The authors wish to express here their sincere thanks to Ajinomoto Co Ltd for the generous supply of amino acids and also to Kagoshima Prefectural Fisheries Station for assistance
in collecting the experimental fish
References 1) 3 E HALVER, D C DELONO, and E T MERTZ: J Nutrition, 63,95-105(1957)
2) J E HALVER and W E SHANKS: ibid., 72, 340-346 (1960)
3) W E SHANKS, G D GABIMER, and J E 14ALVER: Prog Fish-Cult., 24, 68-73 (1962)
4) H K DUPREE and J E HA.LVER: Trans Amer Fish Soc., 99, 90-92 (1970)
5) C B CowEY, J ADRON, and A BLAiR: J Mar Biol Ass U K., 50, 87-95 (1970)
6) T Nose: Bull Freshwater Fish Res Lab., 19, 31-36 (1969)
7) J E HALVER: J Nutrition, 62, 245-254 (1957)
8) S ARAI, T Nose, and Y HAsmMoTo: Bull Freshwater Fish Res Lab., 21, 161-178 (1971) 9) J E HALVER: J Nutrition, 62, 225-243 (1957)