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ARS Home » Southeast Area » Stoneville, Mississippi » Warmwater Aquaculture Research Unit » Research » Publications at this Location » Publication #162163
Title: EFFECTS OF SHORT-TERM FASTING ON CHANNEL CATFISH GROWTH AND NYCHTHEMERAL CONCENTRATIONS OF PLASMA GH, IGF-I, AND CORTISOL

Author
item Small, Brian

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 3/19/2004
Publication Date: 7/25/2004
Citation: Small, B.C. 2004. Effects of short-term fasting on channel catfish growth and nychthemeral concentrations of plasma GH, IGF-I, and cortisol. Journal of Animal Science 82(s1):95.

Interpretive Summary:

Technical Abstract: Short-term fasting is a common management tool for controlling enteric septicemia of catfish; however, little is known concerning the physiological ramifications of short-term fasting. In many animals, long-term starvation affects the somatotropic and the corticotropic axes, often resulting in increased plasma concentrations of growth hormone (GH) and cortisol, and decreased concentrations of circulating IGF-I. This study was conducted in order to characterize the effect of short-term fasting on plasma concentrations of GH, IGF-I, and cortisol over a 24-h period. Channel catfish fingerlings (mean=14.8 g) were stocked into forty-eight 76-L aquaria and acclimated for two weeks. A photoperiod of 12L:12D was maintained throughout the study, with lights coming on at 6:00 am daily. Treatments were randomly assigned such that fish in 24 aquaria were fed twice daily to satiety and fish in the remaining aquaria were fasted. The study was conducted for 21 days. On day 21, fish in the fed treatment were fed at 6:50 am. Beginning at 7:00 am and continuing every two hours for 24 hours, fish from two tanks per treatment were bled and plasma collected. After 3 weeks, weight of fed fish increased an average of 65.7%, while fasted fish lost 21.3% on average. Nychthemeral concentrations of plasma GH were not significantly (P>0.05) different between fed (24.7 ng/mL) and fasted (26.8 ng/mL) fish. Paradoxically, nychthermeral IGF-I concentrations were significantly (P<0.05) different between fed (23.4 ng/mL) and fasted (17.8 ng/mL) fish, and not significantly different for times within treatments. Nychthemeral plasma cortisol concentrations were also significantly (P<0.05) different between fed (14.5 ng/mL) and fasted fish (11.0 ng/mL), and significantly (P<0.05) different for times within treatments. The present study indicates little or no effect of short-term fasting on plasma GH levels, but does demonstrate fasting-induced suppression of plasma IGF-I levels, and suggests a correlation between feeding and cortisol secretion in channel catfish.