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Protein turnover, amino acid profile and amino acid flux in juvenile shrimp Litopenaeus vannamei: effects of dietary protein source
1 Department of Zoology, University of Aberdeen, Tillydrone Avenue, Aberdeen
AB24 2TZ, Scotland, UK
2 INVE Technologies, Oeverstraat 7, B-9200 Baasrode, Belgium
3 Department of Molecular and Cell Biology, University of Aberdeen, Polwarth
Building, Aberdeen AB25 5ZD, Scotland, UK
4 Laboratory of Aquaculture and Artemia Reference Centre, University of
Ghent, Rozier 44, B-9000 Gent, Belgium
* Author for correspondence (e-mail: e.mente{at}abdn.ac.uk)
Accepted 24 June 2002
The effect of dietary protein on protein synthesis and growth of juvenile shrimps Litopenaeus vannamei was investigated using three different diets with equivalent protein content. Protein synthesis was investigated by a flooding dose of tritiated phenylalanine. Survival, specific growth and protein synthesis rates were higher, and protein degradation was lower, in shrimps fed a fish/squid/shrimp meal diet, or a 50% laboratory diet/50% soybean meal variant diet, than in those fed a casein-based diet. The efficiency of retention of synthesized protein as growth was 94% for shrimps fed the fish meal diet, suggesting a very low protein turnover rate; by contrast, the retention of synthesized protein was only 80% for shrimps fed the casein diet. The amino acid profile of the casein diet was poorly correlated with that of the shrimps. 4 h after a single meal the protein synthesis rates increased following an increase in RNA activity. A model was developed for amino acid flux, suggesting that high growth rates involve a reduction in the turnover of proteins, while amino acid loss appears to be high.
Key words: shrimp, Litopenaeus vannamei, growth, protein synthesis, diet, amino acid flux, casein, protein turnover
