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.l. 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 live brine shrimp nauplii 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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