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United States Department of Agriculture

Agricultural Research Service

Research Project: Genetics, Physiology, and Health Research to Improve Catfish Production

Location: Warmwater Aquaculture Research Unit

Title: Effect of fasting on body composition and responses to stress in sunshine bass

Authors
item Davis, Kenneth
item Gaylord, Thomas

Submitted to: Comparative Biochemistry and Physiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: August 17, 2010
Publication Date: January 5, 2011
Citation: Davis Jr, K.B., Gaylord, T.G. 2011. Effect of fasting on body composition and responses to stress in sunshine bass. Comparative Biochemistry and Physiology. 158A:20-36.

Interpretive Summary: Interpretive Summary Liver weight and liver glycogen were essentially depleted after 2 weeks of fasting sunshine bass. The reduction of liver glycogen greatly reduced the glucose response to stress, however, the cortisol stress response was maintained for at least four weeks of fasting. Intraperitoneal fat was decreased very little after 4 weeks of fasting. Plasma IGF-I concentrations were reduced only after 3 weeks of fasting.

Technical Abstract: Technical Abstract The integrated responses of the hormonal regulation of growth and stress in sunshine bass as regulated by feed deprivation were investigated. Groups of fish were fed 1.5% of the body weight per day or offered no feed for 4 weeks. Another group of fish was not fed for 3 weeks and feed was offered during the fourth week. Fish in each group were sampled immediately before or after a 15 minute low water confinement stressor after each week of the experiment. Liver mass and liver glycogen content were decreased after one week of fasting and remained low until the end of the study. However, both recovered after a week of refeeding. Intraperitoneal fat was significantly lower after two weeks of fasting and did not recover after a week of refeeding. None of these components were affected by confinement stress. Plasma glucose in unstressed fish was generally unaffected by fasting or refeeding, however plasma glucose increased after confinement stress in fed but not in fasted fish. The cortisol stress response was unaltered by fasting and remained robust. Plasma IGF-I generally decreased in fasted fish but was not significantly lower than fed fish until the fourth week. A week of refeeding did not restore plasma IGF-I concentrations. Plasma IGF-I concentrations were higher in confinement stressed fed fish after two and four weeks but were unchanged in the fourth week. There was no change in the plasma IGF-I concentrations in fasted or refed fish due to the stress. Liver weight and liver glycogen were essentially depleted after 2 weeks of fasting. The reduction of liver glycogen greatly reduced the glucose response to stress, however, the cortisol stress response was maintained for at least four weeks of fasting. Intraperitoneal fat was decreased very little after 4 weeks of fasting. Plasma IGF-I concentrations were reduced only after 3 weeks of fasting.

Last Modified: 9/2/2014
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