Author
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Torrans, Eugene |
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Submitted to: Catfish Farmers of America Research Symposium
Publication Type: Abstract Only Publication Acceptance Date: 1/5/2003 Publication Date: 2/21/2003 Citation: Torrans, E.L. 2003. EFFECT OF MORNING (MINIMUM) D.O. ON WATER QUALITY, FOOD CONSUMPTION, GROWTH, PRODUCTION, AND FOOD CONVERSION IN CHANNEL CATFISH [Abstract]. In: Research and Review; A Compilation of Abstracts of Research on Channel Catfish. Catfish Farmers of America Catfish Culture Research Symposium, February 21, 2003, Sandestin, Florida. p. 8. Interpretive Summary: Technical Abstract: Farmers have long known that increased aeration allows them to feed more and grow more fish. However, since we still do not know how specific D.O. concentrations affect various production parameters, every farm has it¿s own oxygen management plan, most based largely on keeping the fish alive over night. The purpose of this study was to determine the effect of daily minimum oxygen concentration on channel catfish food consumption, growth, production, and food conversion. Six quarter-acre ponds were each equipped with three ½-HP aerators and one ½-HP circulator. D.O. and temperature were continuously monitored with a commercial oxygen monitor, which also controlled aeration. Aeration was initiated in the "high oxygen" treatment when the D.O. dropped below 5.0 mg/Ll; aeration was initiated in the "low oxygen" treatment when the D.O. dropped below 2.5 mg/L (2001 study) or 1.5 mg/L (2002 study). Fish were fed daily to apparent satiation with floating feed. Water was added only to compensate for evaporation and seepage. Ponds were harvested at the end of each growing season. One pond was dropped from each treatment in 2002 due to high mortality in June. Minimum D.O. in the high oxygen treatment averaged over 4.3 mg/l from June-September of both years; minimum D.O. in the low oxygen treatment averaged 2.6 mg/L in 2001 and 1.7 mg/L in 2002. Maintaining these lower oxygen concentrations required significantly less aeration; aeration time in the low oxygen treatments were reduced 62% in 2001 and 84% in 2002 (P<0.05 both years). Delaying aeration until the D.O. dropped to 2.5 mg/L (in 2001) had little impact on production parameters. Feed consumption decreased by 6.3% (P<0.05) and average fish weight was 8.9% less than the high oxygen treatment. Other parameters were similar. However, delaying aeration until the D.O. dropped to 1.5 mg/L (in 2002) had major impacts: average fish weight was 30.5% less; net production was 54.0% less (P<0.05) and food consumption was 45.1% less (P<0.05) than the high oxygen treatment. Food conversion was not significantly affected by reduced oxygen. It appears that if feed was consumed, it was converted with similar efficiency. Even at the high feeding rates of 2002 (up to 600 lbs/acre/day; 38,860 total lbs/acre in one pond), no critical water quality parameters were observed. |
