Submitted to: World Aquaculture Society Meeting
Publication Type: Abstract Only
Publication Acceptance Date: October 20, 2004
Publication Date: January 17, 2005
Citation: Weber, G.M., Silverstein, J., Lankford, S.E., Gahr, S.A., Blemings, K. 2005. Growth axis and target tissue response to fasting and refeeding in rainbow trout oncorhynchus mykiss fingerlings. World Aquaculture Society Meeting. Technical Abstract: A breeding program to develop strains of rainbow trout with improved growth performance for the US rainbow trout aquaculture industry is being conducted at NCCCWA. Our broodstock families are being characterized and selected for improved growth rate. In addition, we will characterize variation in growth regulatory mechanisms among our broodstock families to provide additional information to direct our breeding efforts. As a first step in this effort we characterized the neuroendocrine responses to fasting and refeeding in a commercially available strain of rainbow trout fingerlings to serve as a foundation on which to base our comparisons. The study began with 70 fish (~12 g) placed in each of 15 tanks (200 L), with 5 tanks assigned to each treatment. The treatments were; fish fed throughout the study (fed controls), fish fasted for 3 days (3 day fasted), and fish fasted for 2 weeks prior to refeeding (2 week fasted). Six fish from each tank were sampled on the day refeeding was to be initiated, and again at 3, 7 and 14 days after refeeding. Fish number and mass for each tank was determined weekly. Fish fasted for 3 days or 2 weeks had significantly reduced body weight compared with controls. Body weight of the fasted fish did not return to values observed in the fed controls for the duration of the study. Plasma concentrations of insulin-like growth factor I (IGF-I) were reduced compared to fed controls in the 2-week fasted fish at days 0, 3 and 7 of refeeding, and reduced in the 3-day fasted fish at days 3 and 7. Other measures of change in growth axis activity with fasting or refeeding were not as dramatic as those of plasma IGF-I.