AMMONIA-N EFFLUX RATE AND NUTRITIONAL STATE OF JUVENILE PINK SHRIMP, PENAEUS-PAULENSIS (PEREZ-FARFANTE), IN RELATION TO FOOD TYPE

The effects of squid flesh, two pelleted diets containing 41% and 53% protein, and starvation on the ammonia-N efflux rate and the biochemic al composition of pink shrimp, Penaeus paulensis (Perez-Farfante), wer e investigated. A transient increase in the ammonia-N efflux rates of shrimp subjected to starvation was observed. Ammonia-N efflux rates of shrimp fed the diet with 41% protein were lower than in those fed the diet with 53% protein or squid flesh. Ammonia-N efflux rates were inv ersely related to body weight, except during starvation, which affecte d mainly small individuals. Increased ammonia-N excretion rates increa sed immediately after the ingestion of high-protein diets, Such rates were also found to be higher during light periods (cf. dark periods), possibly reflecting differences in activity levels, Dietary-related al terations in the blood, muscle and midgut gland constituents were also detected. In general terms, starvation tended to reduce the levels of such constituents, whilst pelleted diets promoted increases in lipid and carbohydrate concentrations.