Response of Israeli carp, Cyprinus carpio L., to lysine supplementation of a practical ration at varying conditions of fish size, temperature, density and ration size

VIOLA, S.; Lahav, E.; ARIELI, Y.

Response of Israeli carp, Cyprinus carpio L., to lysine supplementation of a practical ration at varying conditions of fish size, temperature, density and ration size

1992

VIOLA, S. | Lahav, E. | ARIELI, Y.

Four feeding trials with Israeli carp, Cyprinus carpio L., were performed in cages or in ponds in order to investigate responses to lysine supplementation of low protein carp feeds under different practical conditions. In each of the trials one of the basic conditions was different: fish size--small (80-125g) or large (560g); temperature--22°C or 26°C; density--cages or ponds. In each trial 2-3 ration sizes × 2-3 lysine levels were tested. A basal diet of 25% protein and 1·35% lysine served for all the trials. At low feeding levels, no responses to lysine supplements were found either at 22 ± 2°C or at 26 ± 2°C (0600 h) for all fish sizes. At higher feeding levels, at both temperatures, 0·5% lysine-HCl supplements to 1·7% total lysine yielded significant growth increases. Further supplements to 2·1% lysine (=8·4% of the protein) brought an additional response only from small fish of 90g in cages at the highest ration and temperature. In ponds at 26°C, the effects on small fish of 80g were smaller, probably due to available natural food. The reduction in lysine retention suggested that 1·7% lysine might have been adequate even at optimal conditions in ponds.

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