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United States Department of Agriculture

Agricultural Research Service

Research Project: CATFISH GENETICS, BREEDING, AND PHYSIOLOGY

Location: Warmwater Aquaculture Research Unit

Title: Effects of Temperature and Feed-energy on Performance of Juvenile Red Drum

Authors
item Fontaine, L - TEXAS A&M UNIVERSITY
item Whiteman, K - TEXAS A&M UNIVERSITY
item Li, P - TEXAS A&M UNIVERSITY
item Burr, G - TEXAS A&M UNIVERSITY
item Webb, K - TEXAS A&M UNIVERSITY
item Goff, J - TEXAS A&M UNIVERSITY
item Gatlin, D - TEXAS A&M UNIVERSITY
item Neill, W - TEXAS A&M UNIVERSITY
item DAVIS, KENNETH
item Vega, R - TEXAS PARKS & WILDLIFE

Submitted to: American Fisheries Society Transaction
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: March 19, 2007
Publication Date: August 1, 2007
Citation: Fontaine, L.P., Whiteman, K.W., Li, P., Burr, G.S., Webb, K.A., Goff, J., Gatlin, D.M., Neill, W.H., Davis Jr, K.B., Vega, R.R. 2007. Effects of Temperature and Feed-energy on Performance of Juvenile Red Drum. American Fisheries Society Transaction.

Interpretive Summary: An ecophysiological computer model, Ecophys.Fish, was used to develop the hypothesis that fish exposed to high temperatures can be growth limited by the concentration of energy in available food, whereas fish exposed to lower temperatures can be limited by their metabolic capacity to exploit available food energy for growth. We used growth and marginal metabolic scope of juvenile red drum fed at a high energy (HE) and a low energy (LE) level at three temperatures to test this hypothesis in a 4-week and a 6-week Body composition indicies, proximate composition and the cortisol responses to net confinement were also measured in the 6 week study. Feed efficiency, hepatosomatic index, intraperitoneal fat ratio and whole-body fat of fish fed the LE diet were significantly lower than those of fish fed the HE diet, indicating relative energy malnutrition in the LE group. But, in accordance with lack of difference in MMS between feed treatments, there was no apparent differential effect of feed-energy on pre- or post-stress values of plasma cortisol.

Technical Abstract: Work with Ecophys.Fish, an ecophysiological model of fish performance, led to development of this hypothesis: Fish exposed to high temperatures can be growth-limited by the concentration of energy in available food; whereas, fish exposed to lower temperatures can be limited by their metabolic capacity to exploit available food energy for growth. To test this hypothesis, we compared growth and marginal metabolic scope (MMS) of juvenile red drum Sciaenops ocellatus under laboratory conditions at two levels of dietary energy, ~ 980 (LE) and 3800 (HE) cal/g as-fed, and three temperatures-- ~19, ~25, and ~29 C. After 4 weeks, results conformed to expectation under the hypothesis. Growth rate and MMS increased with temperature, but only growth rate increased with dietary energy and then only at the higher two temperatures. At 19 C, the HE fish apparently lacked metabolic capacity to exploit any more of the feed energy than did the LE fish; at 25 C and especially at 29 C, the LE fish seemingly had more metabolic capacity than they could use in support of growth. A subsequent, 6-wk-long experiment confirmed the marked difference in growth, and lack of substantial difference in MMS, between fish fed the two diets at ambient temperature (~26 C) and sought further resolution of these responses by examination of body-condition indices and proximate composition. In addition, fish from the second experiment were assayed for differential cortisol response to net-confinement stress. Feed efficiency, hepatosomatic index, intraperitoneal fat ratio and whole-body fat of fish fed the LE diet were significantly lower than those of fish fed the HE diet, indicating relative energy malnutrition in the LE group. But, in accordance with lack of difference in MMS between feed treatments, there was no apparent differential effect of feed-energy on pre- or post-stress values of plasma cortisol.

Last Modified: 9/10/2014
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