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Utilization of Neomysis integer Leach (Crustacea, Mysidacea) by rainbow trout (Salmo gairdneri Richardson) parr in brackish water
Aquucdture,
61 (1987) 17-21
17
Elsevier Science Publishers B.V., Amsterdam - Printed in The Netherlands
Utilization of Neomysis integer Leach (Crustacea, Mysidacea) by Rainbow Trout (Salmo gairdneri Richardson) Parr in Brackish Water W. JANSXN and L. SPANNHOF Animal Pkysio~gy Unit, ~e~urtrneRt of Biology, ~~lke~rn Pieck Uniuersity, Restock (German Democratic Republics
(Accepted 29 August 1986 )
ABSTRACT Jansen, W. and Spannhof, L., 1987. Utilization of Neomysis integer Leach (Crustacea,Mysidatea) by rainbow trout (Salmo gairdneri Richardson) parr in brackish water. Aquaculture, 61: 17-21.
The utilization of Neomysis integer by rainbow trout parr was studied and compared with the utilization of conventional fish feeds. Under brackish water conditions Neomysis pellets are just as efficient as conventional feeds in respect of growth. The feeding efficiency is comparable with that obtained with krill. Suggestions are made for obtaining this natural food via filters at power stations or attracting it with light traps (phototaxis). Neomysis should be used as an additional food wherever it is present in appreciable quantities.
INTRODUCTION
Further increases in output from fish farming activities, both in fresh and brackish waters, depend to a large extent on the availability of appropriate food. Pellets of various kinds are generally used because they are readily obtainable and, as a dry feed, easy to handle. Natural food sources, on the other hand, are known to affect positively the growth, survival, resistance and reproduction of fishes. Where foods are available from such natural sources, they should be used for mass production. It is important, however, to know the relative nutritional values of the organisms concerned. From among the crustaceans found in our coastal waters that can be considered potential food sources, we decided to analyze Neonzysis integer Leach in this respect. N. integer is a shrimp with a mean body length of 17 mm that forms huge swarms in shallow waters (down to 1.5 m depth) from spring to winter. Raymont et al. ( 1968)) Morris (1971) and Armitage et al. (1977) have reported in detail on the biochemical composition of this crustacean. 0 1987 Elsevier Science Publishers B.V.
Protein accounts for some 70% of the dry weight. About 14% of all fatty acids in the fat contzent, which can be as high as 13% of the dry weight, are polyunsaturated. The amino acid composition is roughly the same as that of krill, but the chitin shell of ~eo~~~~ is thinner than that of krill, and this can be regarded as an advantage when considering its possible use as a food source. Its omnivarous life mode, euryhaline character and propensity to form schools in shallow estuaries make ~eo~~~~ integer impo~ant f Jansen, 1983) as a fish food at trout production facilities sited in brackish waters. This natural food source should obviously be used. The purpose of the present work is to investigate whether ~eo~~~~ can compete with conventional fish feeds in terms of nutritional value.
Animals Rainbow trout weighing 6-21 g each were taken from a fish farm and fed at 10°C with pellets made of iVeony& and conventional pellets for trout parr ( 2% of body weight daily). The data characteriz~g the experimental arrangement are shown in Table 1. The fishes were tagged so that the growth rate of each ~n~vidu~ could be remained. The followingpa~ame~rs were determined in addition to the initial and final weights of the individuals: protein and fat content of feed and protein and fat content of fishes at the beginning and end of the experiment. Production of Neomysis integer pellets After collection, the crustaceans were dried for at least 24 h at 60°C and then pulverized. The powder was mixed with a 5% gelatine solution in the pruportions 122 (1 g powder per 2 ml solution). This paste was pressed into appropriately sized pellets, which were left tu dry at 60°C for at least 24 h, Some of the Neomys&z pellets were labelled by adding 1% chromium oxide ( Gr,U,) (Nehring, 1962) to permit calculation of di~stibility coef~cien~ (DC). The change in the percentage proportions after passage through the gut can be used to estimate the digestibility of the pellets. We calculated digestibility coefficients by the following formula: DC= [(a-b)/u]
~100
where a=g DW nutrients~g DW indicator in feed, and b ==gDW nutr~ents~g DW indicator in fecal pellets. Both the trout and the feed were analyzed by W~nder’s metb~
for f~~tu~s.
19 TABLE I Experimental
arrangement
Experimental group
Salinity (%0)
Feed
I II III IV
Fresh water Fresh water
Neomysis pellets Trout parr feed Neomysis pellets Trout parr feed
10
10
Number of animals
Duration of experiment (days 1
10
28 28 28 28
10
10 10
TABLE 2 Body weights of rainbow trout after feeding for 28 days on trout parr feed (II, IV) or Neomysis pellets (I, III) in fresh water (I, II) or brackish water (10%0 S) (III, IV) Experimental group I II III IV
Initial weight (g)
Final weight (g)
Pw (in %)
1:
s
I
S
i
5
14.55 13.47 12.40 12.88
3.45 4.66 4.52 4.28
19.08 19.67 18.45 19.43
3.9 7.07 6.81 6.35
0.996 1.354 1.424 1.483
0.172 0.191 0.031 0.049
RESULTS
The body weight increased distinctly in all experimental groups (Table 2). Feeding with trout parr pellets was about 30% more efficient than feeding with Neomysis pellets in fresh water. The ration was equal in both cases, and the daily gain in weight fin % ) was used as a measure of growth (Table 2). This difference did not appear in brackish water, however, where the growth rates achieved with the two feeds were t statistically) equal. Analysis of the variance of this 2’ experiment shows that there is an interaction between feed quality and salinity of the environment: the nutritional value of Neomysis is considerably higher in brackish water. The effects of this feed on body composition are reflected in the fact that the animals fed on Neomysis always had a higher protein and a lower fat content. The differences are more pronounced in fresh water than in brackish conditions (Table 3). The fishes fed on Neomysis appeared to be more agile, and the animals in group III particularly were notable for their more intensive red coloration, especially of their fins and gill covers. The digestibility coef~~ient for the Neomys~ pellets was 83%.
20 TABLE 3
Protein and fat content of trout parr feed (F) and Neomysis pelIets (N) and of rainbow trout in groups I-IV after feeding on these feeds (figures = % DW) Feed
Protein Crude fat
Rainbow trout
N
F
of experiment
I
II
III
IV
57.9 3.0
47.8 5.8
68.4 11.1
75.4 10.5
68.0 11.1
70.8 8.9
67.3 10.8
DISCUSSION
~eo~y~~ integer is a highly productive crustacean that occurs in swarms with up to 1000 iu~viduals/m2 in the southern part of the Baltic Sea (shallow inlets south of the Darss-Zingst Peninsula). They inhabit the shallow regions of these waters (down to 1.5 m) from April to November/December (Jansen, 1983). Even larger swarms with up to 3000-4000 individuals/m2 have been observed in Danish waters where organic loads are high (effluent from a slaughterhouse) ( Muus, 1967). Rasmussen (1973) reported even denser swarms with 50 000 in~vidu~s/m2, and Beattie and De Kruiff (1978 ) observed swarms with up to 5800 individuals/m2 in a freshwater lake in The Netherlands. In the latter it was obviously the attraction of warm waste water from a nearby power station that caused the high Neomysis abundance. On account of this high productivity, Neomysis obviously deserves consideration as a possible additional feed at fish farms. Our studies show that, particularly under brackish water conditions and in the case of trout, feeding with these crustaceans is just as efficient as with conventional feeds, although the sole criterion we used was growth. The feeding ef~ciency is comparable to that obtained with krill (Schmidt, 1977; Steffens and Albrecht, 1980; Goryczko and Geliscynski, 1981) . The red coloration of various parts of the body after feeding on Neomysis pellets is probably attributable to the higher carotinoid content of the feed and should have just as positive an effect as that induced by feeding on krill. Spawners, in particular, should therefore receive additional Neomysis feed in order to stimulate gonadal development and maturation. Procuring the c~stace~s may be rather problematic, but filters at power stations or light traps may prove to be suitable sources of this additional feed. Neomysis is positively phototactic (Kuranty, 1979)) so that simply the provision of additional lighting on net cages will lead to accumulations, also of other crustaceans ( Schlumpberger, 1981) , and will promote the growth of trout Parr. Wherever Neomysis is present in appreciable quantities, attempts should be made to use it as an additional food source.
21
REFERENCES Armitage, M.E., Raymont, J.E.G. and Morris, R.J., 1977. The effects of a pure carbohydrate diet on the amino acid composition of Neomysis integer. In: M. Angel (Editor), A Voyage of Discovery. Suppl. to Deep Sea Research. Pergamon Press, Oxford, pp. 471-481. Beattie, D.M. and De Kruijf, H., 1978. Population dynamics and biomass production of Neomysis integer (Leach) in the Bergumermeer. Verh. Int. Verein. Limnol., 20: 2566-2571. Goryczko, K. and Gliszcynski, B., 1981. Badania mozliwosci zastosowania kryla mrozonego i maczki z kryla w zywienin pstagow teczowych. Rocz. Nauk Roln., Warszawa, 99 (4) : 7-23. Jansen, W., 1983. Neomysis integer Leach (Crustacea, Mysidacea) in der Dams-Zingster Boddenkette - Untersuchungen zur Populationsentwicklung und Leistungsfhigkeit in Abhiingigkeit von Umweltfaktoren. Dissertation, Wilh.-Pieck-Univ., Restock. Kuranty, J., 1979. Initial investigations on the reaction to light of Neomysis integer Leach 1815. Oceanografia, 6: 69-77. Morris, R.J., 1971. Seasonal and environmental effects on lipid composition of ~eomys~ integer. J. Mar. Biol. Assoc. U.K., 51: 21-32. MUUS,B.J., 1967. The fauna of Danish estuaries and lagoons. Medd. Dan. Fisk. Havunders., N.S., 5(l): 111. Nehring, D., 1962. Verdauungsversuche an Fischen nach der Chromoxid-Indikator-Methode. Z. Fisch. NF, 11: 769-777. Rasmussen, E., 1973. Systematics and ecology of the Isefjord marine fauna (Denmark). Ophelia, II: 152-153. Raymont, J.E.G., Austin, J. and Linford, E., 1968. Biochemical studies on marine zooplankton. V. The composition of the major biochemicai fractions in Neomysis integer. J. Mar. Biol. Assoc. U.K., 48: 735-760. Schlump~rger, W., 1981. Produktion von vorgestreckten Zandern in beleuchteten Gazekaigen. Z. Binnenfisch. DDR, 28 (5): 143-144. Schmidt, G.W., 1977. Krill als Forellenfutter.. Fischwi~ch., Miinchen, 27 (10) : 58-59. Steffens, W. and Albrecht, M.-L., 1980. Krillmehl als Eiweissquelle im Fischfutter. 2. Mitt.: Einsatz von Krillmehl im Forellenfitter. Z. Binnenfisch. DDR, 27 (10): 305-308.
61 (1987) 17-21
17
Elsevier Science Publishers B.V., Amsterdam - Printed in The Netherlands
Utilization of Neomysis integer Leach (Crustacea, Mysidacea) by Rainbow Trout (Salmo gairdneri Richardson) Parr in Brackish Water W. JANSXN and L. SPANNHOF Animal Pkysio~gy Unit, ~e~urtrneRt of Biology, ~~lke~rn Pieck Uniuersity, Restock (German Democratic Republics
(Accepted 29 August 1986 )
ABSTRACT Jansen, W. and Spannhof, L., 1987. Utilization of Neomysis integer Leach (Crustacea,Mysidatea) by rainbow trout (Salmo gairdneri Richardson) parr in brackish water. Aquaculture, 61: 17-21.
The utilization of Neomysis integer by rainbow trout parr was studied and compared with the utilization of conventional fish feeds. Under brackish water conditions Neomysis pellets are just as efficient as conventional feeds in respect of growth. The feeding efficiency is comparable with that obtained with krill. Suggestions are made for obtaining this natural food via filters at power stations or attracting it with light traps (phototaxis). Neomysis should be used as an additional food wherever it is present in appreciable quantities.
INTRODUCTION
Further increases in output from fish farming activities, both in fresh and brackish waters, depend to a large extent on the availability of appropriate food. Pellets of various kinds are generally used because they are readily obtainable and, as a dry feed, easy to handle. Natural food sources, on the other hand, are known to affect positively the growth, survival, resistance and reproduction of fishes. Where foods are available from such natural sources, they should be used for mass production. It is important, however, to know the relative nutritional values of the organisms concerned. From among the crustaceans found in our coastal waters that can be considered potential food sources, we decided to analyze Neonzysis integer Leach in this respect. N. integer is a shrimp with a mean body length of 17 mm that forms huge swarms in shallow waters (down to 1.5 m depth) from spring to winter. Raymont et al. ( 1968)) Morris (1971) and Armitage et al. (1977) have reported in detail on the biochemical composition of this crustacean. 0 1987 Elsevier Science Publishers B.V.
Protein accounts for some 70% of the dry weight. About 14% of all fatty acids in the fat contzent, which can be as high as 13% of the dry weight, are polyunsaturated. The amino acid composition is roughly the same as that of krill, but the chitin shell of ~eo~~~~ is thinner than that of krill, and this can be regarded as an advantage when considering its possible use as a food source. Its omnivarous life mode, euryhaline character and propensity to form schools in shallow estuaries make ~eo~~~~ integer impo~ant f Jansen, 1983) as a fish food at trout production facilities sited in brackish waters. This natural food source should obviously be used. The purpose of the present work is to investigate whether ~eo~~~~ can compete with conventional fish feeds in terms of nutritional value.
Animals Rainbow trout weighing 6-21 g each were taken from a fish farm and fed at 10°C with pellets made of iVeony& and conventional pellets for trout parr ( 2% of body weight daily). The data characteriz~g the experimental arrangement are shown in Table 1. The fishes were tagged so that the growth rate of each ~n~vidu~ could be remained. The followingpa~ame~rs were determined in addition to the initial and final weights of the individuals: protein and fat content of feed and protein and fat content of fishes at the beginning and end of the experiment. Production of Neomysis integer pellets After collection, the crustaceans were dried for at least 24 h at 60°C and then pulverized. The powder was mixed with a 5% gelatine solution in the pruportions 122 (1 g powder per 2 ml solution). This paste was pressed into appropriately sized pellets, which were left tu dry at 60°C for at least 24 h, Some of the Neomys&z pellets were labelled by adding 1% chromium oxide ( Gr,U,) (Nehring, 1962) to permit calculation of di~stibility coef~cien~ (DC). The change in the percentage proportions after passage through the gut can be used to estimate the digestibility of the pellets. We calculated digestibility coefficients by the following formula: DC= [(a-b)/u]
~100
where a=g DW nutrients~g DW indicator in feed, and b ==gDW nutr~ents~g DW indicator in fecal pellets. Both the trout and the feed were analyzed by W~nder’s metb~
for f~~tu~s.
19 TABLE I Experimental
arrangement
Experimental group
Salinity (%0)
Feed
I II III IV
Fresh water Fresh water
Neomysis pellets Trout parr feed Neomysis pellets Trout parr feed
10
10
Number of animals
Duration of experiment (days 1
10
28 28 28 28
10
10 10
TABLE 2 Body weights of rainbow trout after feeding for 28 days on trout parr feed (II, IV) or Neomysis pellets (I, III) in fresh water (I, II) or brackish water (10%0 S) (III, IV) Experimental group I II III IV
Initial weight (g)
Final weight (g)
Pw (in %)
1:
s
I
S
i
5
14.55 13.47 12.40 12.88
3.45 4.66 4.52 4.28
19.08 19.67 18.45 19.43
3.9 7.07 6.81 6.35
0.996 1.354 1.424 1.483
0.172 0.191 0.031 0.049
RESULTS
The body weight increased distinctly in all experimental groups (Table 2). Feeding with trout parr pellets was about 30% more efficient than feeding with Neomysis pellets in fresh water. The ration was equal in both cases, and the daily gain in weight fin % ) was used as a measure of growth (Table 2). This difference did not appear in brackish water, however, where the growth rates achieved with the two feeds were t statistically) equal. Analysis of the variance of this 2’ experiment shows that there is an interaction between feed quality and salinity of the environment: the nutritional value of Neomysis is considerably higher in brackish water. The effects of this feed on body composition are reflected in the fact that the animals fed on Neomysis always had a higher protein and a lower fat content. The differences are more pronounced in fresh water than in brackish conditions (Table 3). The fishes fed on Neomysis appeared to be more agile, and the animals in group III particularly were notable for their more intensive red coloration, especially of their fins and gill covers. The digestibility coef~~ient for the Neomys~ pellets was 83%.
20 TABLE 3
Protein and fat content of trout parr feed (F) and Neomysis pelIets (N) and of rainbow trout in groups I-IV after feeding on these feeds (figures = % DW) Feed
Protein Crude fat
Rainbow trout
N
F
of experiment
I
II
III
IV
57.9 3.0
47.8 5.8
68.4 11.1
75.4 10.5
68.0 11.1
70.8 8.9
67.3 10.8
DISCUSSION
~eo~y~~ integer is a highly productive crustacean that occurs in swarms with up to 1000 iu~viduals/m2 in the southern part of the Baltic Sea (shallow inlets south of the Darss-Zingst Peninsula). They inhabit the shallow regions of these waters (down to 1.5 m) from April to November/December (Jansen, 1983). Even larger swarms with up to 3000-4000 individuals/m2 have been observed in Danish waters where organic loads are high (effluent from a slaughterhouse) ( Muus, 1967). Rasmussen (1973) reported even denser swarms with 50 000 in~vidu~s/m2, and Beattie and De Kruiff (1978 ) observed swarms with up to 5800 individuals/m2 in a freshwater lake in The Netherlands. In the latter it was obviously the attraction of warm waste water from a nearby power station that caused the high Neomysis abundance. On account of this high productivity, Neomysis obviously deserves consideration as a possible additional feed at fish farms. Our studies show that, particularly under brackish water conditions and in the case of trout, feeding with these crustaceans is just as efficient as with conventional feeds, although the sole criterion we used was growth. The feeding ef~ciency is comparable to that obtained with krill (Schmidt, 1977; Steffens and Albrecht, 1980; Goryczko and Geliscynski, 1981) . The red coloration of various parts of the body after feeding on Neomysis pellets is probably attributable to the higher carotinoid content of the feed and should have just as positive an effect as that induced by feeding on krill. Spawners, in particular, should therefore receive additional Neomysis feed in order to stimulate gonadal development and maturation. Procuring the c~stace~s may be rather problematic, but filters at power stations or light traps may prove to be suitable sources of this additional feed. Neomysis is positively phototactic (Kuranty, 1979)) so that simply the provision of additional lighting on net cages will lead to accumulations, also of other crustaceans ( Schlumpberger, 1981) , and will promote the growth of trout Parr. Wherever Neomysis is present in appreciable quantities, attempts should be made to use it as an additional food source.
21
REFERENCES Armitage, M.E., Raymont, J.E.G. and Morris, R.J., 1977. The effects of a pure carbohydrate diet on the amino acid composition of Neomysis integer. In: M. Angel (Editor), A Voyage of Discovery. Suppl. to Deep Sea Research. Pergamon Press, Oxford, pp. 471-481. Beattie, D.M. and De Kruijf, H., 1978. Population dynamics and biomass production of Neomysis integer (Leach) in the Bergumermeer. Verh. Int. Verein. Limnol., 20: 2566-2571. Goryczko, K. and Gliszcynski, B., 1981. Badania mozliwosci zastosowania kryla mrozonego i maczki z kryla w zywienin pstagow teczowych. Rocz. Nauk Roln., Warszawa, 99 (4) : 7-23. Jansen, W., 1983. Neomysis integer Leach (Crustacea, Mysidacea) in der Dams-Zingster Boddenkette - Untersuchungen zur Populationsentwicklung und Leistungsfhigkeit in Abhiingigkeit von Umweltfaktoren. Dissertation, Wilh.-Pieck-Univ., Restock. Kuranty, J., 1979. Initial investigations on the reaction to light of Neomysis integer Leach 1815. Oceanografia, 6: 69-77. Morris, R.J., 1971. Seasonal and environmental effects on lipid composition of ~eomys~ integer. J. Mar. Biol. Assoc. U.K., 51: 21-32. MUUS,B.J., 1967. The fauna of Danish estuaries and lagoons. Medd. Dan. Fisk. Havunders., N.S., 5(l): 111. Nehring, D., 1962. Verdauungsversuche an Fischen nach der Chromoxid-Indikator-Methode. Z. Fisch. NF, 11: 769-777. Rasmussen, E., 1973. Systematics and ecology of the Isefjord marine fauna (Denmark). Ophelia, II: 152-153. Raymont, J.E.G., Austin, J. and Linford, E., 1968. Biochemical studies on marine zooplankton. V. The composition of the major biochemicai fractions in Neomysis integer. J. Mar. Biol. Assoc. U.K., 48: 735-760. Schlump~rger, W., 1981. Produktion von vorgestreckten Zandern in beleuchteten Gazekaigen. Z. Binnenfisch. DDR, 28 (5): 143-144. Schmidt, G.W., 1977. Krill als Forellenfutter.. Fischwi~ch., Miinchen, 27 (10) : 58-59. Steffens, W. and Albrecht, M.-L., 1980. Krillmehl als Eiweissquelle im Fischfutter. 2. Mitt.: Einsatz von Krillmehl im Forellenfitter. Z. Binnenfisch. DDR, 27 (10): 305-308.