Effect of salinity on physiological energetics of white shrimp Litopenaeus vannamei (Boone)

The energy balance was determined in Litopenaeus vannamei, juveniles acclimated to salinity at three ranges, hyperosmotic (20 ups), isosmotic (26 ups), and hypo-osmotic (32 ups). Also O:N atomic ratio was calculated. The ingestion rate, oxygen consumption, ammonium excretion and growth were affected significantly when the organisms were acclimated at 20, 26 and 32 ups. The highest energy contained from the food consumed was obtained in the organisms maintained in 26 ups. The lowest energy expense derived to routine metabolism, and excretion of nitrogenous products was obtained in the animals maintained at 26 ups. The high quantity of energy channeled to the scope for growth (671.1 J g-1 day-1 d.w.) was obtained in the shrimps acclimated to salinity of 26 ups. The O:N atomic ratio calculated for the juveniles indicated a catabolism of carbohydrates for the organisms maintained in the isosmotic condition. The apparent heat increase, the feces production, and energy lost by exuviae, not were significantly different in the shrimps exposed to the three salinities. It was recommended to maintain Litopenaeus vannamei juveniles at the salinity level which is isosmotic (26 ups).