ARS | Publication request: ENERGY BALANCE AND PHYSIOLOGICAL RESPONSE TO FASTING AND REFEEDING IN RAINBOW TROUT FINGERLINGS

Submitted to: Aquaculture America Conference
Publication Type: Proceedings/Symposium
Publication Acceptance Date: October 25, 2004
Publication Date: February 21, 2005
Citation: Silverstein, J., Weber, G.M., Leder, E.H., Blemings, K.P. 2005. Energy balance and physiological response to fasting and refeeding in rainbow trout fingerlings. Aquaculture America Conference 2005. New Orleans, LA 01/17 - 1/20/2005. Abstract 268.

Technical Abstract: To investigate feeding and growth rate changes as a result of an energy debt and the corresponding physiological response, we examined feeding, growth and gene expression of several key genes in the feed regulatory pathways following two fasting and refeeding treatments. Using the predictions of compensatory growth, refeeding treatments were used to try to increase growth rate and determine the response in gene expression of rainbow trout. Treatments consisted of a short fast (3D) followed by refeeding, a long fast (14D) followed by refeeding, and a control of continuous feeding. Following pretreatments of 3D or 14D fasting, fish tissues were sampled and feeding was resumed to all remaining fish. Fish were weighed and tissue samples were taken again one and three weeks after resumption of feeding. Feed intake was monitored throughout the study to determine differences in feed intake among the groups. Fish were approximately 16g prior to the fasting. At the end of the fasting period, the control group fish averaged 26g while the 3D and 14D fasted fish averaged 22.1g and 13.4g, respectively. Upon refeeding, despite the expectation of vigorous feeding, the intake of fasted fish was not much greater than controls. Consequently the growth rate of fasted/refed fish was not greater than controls. After two weeks of refeeding, the control fish weighed 52.5g, and the 3D and 14D groups averaged 50.2g and 33.4g, respectively. Brains were dissected into upper and lower brain regions. Real-time PCR was used to examine several genes known to be involved in the feed intake response including: neuropeptide-Y (NPY), agouti-related peptide (AGRP), and pro-opiomelanocortin (POMC). Initial analysis indicated a slight increase in expression of NPY and POMC in both fasting/refeeding treatments.