EVALUATION OF VARIOUS DIETS ON 



THE LIPID AND PROTEIN COMPOSITION 



OF EARLY LIFE STAGES OF THE 



ATLANTIC SILVERSIDE 



Kenneth L. Simpson, Leslie M. Richardson and 



Paul S. Schauer 



Department of Food Science and Technology, 



Nutrition and Dietetics 



University of Rhode Island 



Kingston, R.I. 02881 



ABSTRACT 



A study was performed to evaluate the effect of various natural and 

 artificial diets on the lipid and protein composition of,laboratory cultured 

 Atlantic silversides, Menidia menidia. Results were compared to analyses of 

 wild silversides, which constituted the biochemical control. 



The best growth and survival of juvenile silversides was obtained on a live 

 3-day-old brine shrimp nauplii diet. Substantially lower growth and survival 

 were obtained on a freeze-dried brine shrimp diet and the artificial diets. 



Amino acids were incorporated into the tissue of batch cultured silversides 

 fed a live 3-day-old brine shrimp diet by the fifth day of culture. Thereafter, 

 the profiles changed very little, except for the levels of histidine and arginine in 

 the 58-day-old silversides. The amino acids of the cultured fish fed natural or 

 artificial diets were quite similar. Bioavailability studies are necessary to 

 ascertain the degree of incorporation and assimilation of dietary amino acids. 



The whole body fatty acid composition of cultured fish reflected the 

 composition of their diets. Fish fed a Uve brine shrimp naupHi diet had higher 

 total lipid levels and lower polyunsaturated fatty acid levels than wild 

 silversides. Cultured fish may store large amounts of lipids in order to facilitate 

 the bioaccumulation of long chain polyunsaturated fatty acids. The 

 incorporation of cod liver oil into a diet previously containing a soybean oil 

 increased the levels of the polyunsaturated fatty acids in the fish. The resulting 

 fatty acid tissue levels resembled the long chain fatty acids of the wild fish 

 lipids more closely than the profiles of fish fed brine shrimp nauplii. 



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