Effect of salinity and dietary protein level on physiological condition and digestive activity of juveniles of snook, Centropomus undecimalis reaerd in controlled condition.  

Arenas M1., Alvarez A2., Cuzon G3., Mascaró M3, Maldonado C3., Sánchez A3., Gaxiola G3.
 
Posgrado de Ciencias del Mar y Limnología, UNAM, México
DACBIO, Universidad Juárez Autónoma de Tabasco, México
UMDI-Sisal, Fac. de Ciencias, UNAM, México

The juveniles used in the present study were obtained from one spawning under laboratory conditions. The protein requirement of juveniles of 15-30g was evaluated in two salinity conditions (seawater and low salinity water) receiving a diet based on renderers+protiblend+soy concentrate+wheat gluten.  The responses in terms of survival, weight gain, FCR, condition factor and feed conversion were recorded after two months trial in the laboratory. Hematocrit, osmotic pressure, mesenteric fat index and the biochemical composition of lipids were higher in 35 ‰. The activity of acidic proteases, alkaline proteases (pyloric caeca) and chymotrypsin with increased protein level , however trypsin, leucine aminopeptidase and lipase opposite behavior was recorded. These results suggest that juvenile white seabass demand a protein requirement of 52 on 3 ‰ salinity, however in 35 ‰ not this result is found, which may require a larger amount of this nutrient in the diet, according the growth and activity of digestive enzymes reported, mainly proteases, 35 ‰ established as the best culture condition for this species due to increased efficiency in the use of food nutrients, especially protein.