Effects of long-term exposure to feed restriction in juveniles of the freshwater crayfish Cherax quadricarinatus (Decapoda, Parastacidae).

LUIS M. FRANCO TADIC; HERNÁN J. SACRISTÁN; LIANE STUMPF; LAURA S. LÓPEZ GRECO

San José

Congreso; TCS-ALCARCINUS Summer Meeting, Costa Rica 2013; 2013

The Crustacean Society

Food represents one of the most expensive costs in aquaculture so its optimization is essential for this growing industry. An experiment was conducted to determine the effects of long-term (90 days) exposure to feed restriction on survival, growth, energetic reserves, digestive enzimatic activity and structure of hepatopancreas in C. quadricarinatus. Juveniles were individually exposed to two treatments: juveniles daily fed (C ) and juveniles fed four days followed by four days without food (INT, intermittent feeding protocol). Mortality and molting were daily recorded. At day 30 and 60 a sample of juveniles and at day 90 the remaining juveniles were weighted, sacrificed and their hepatopáncreas were dissected and processed for light microscopy and to determine digestive enzymatic activities and energetic reserves (proteins, total lipids and glycogen). Muscle from the pleon was also obtained to determine energetic reserves. After 90 days of feed restriction, survival of INT was 100% and growth increment was 25% lower although juveniles received 50% of food compared to C. Some, but not severe, histological abnormalities were found in the hepatopancreas from INT juveniles as enlarged tubular lumen, R-cells with enlarged vacuoles and disorganized tubular structure. Lipases from the hepatopancreas and lipid content both for muscle and hepatopancreas had lower values in INT along the experiment while proteins were only lower at day 30. The results showa high resistance to low feeding with little impact on many parameters of growth performance, allowing the reduction of food supply during extended periods and thus, improving yields.