60 DECEMBER 2015 • WORLD AQUACULTURE • WWW.WAS.ORG Figure 3 shows the differences in the expected final weights of channel catfish after 180 days. Beginning at 27.2 g, the data in Table 1 was used for power only vs. natural logarithm only combinations to calculate weight gains and adjust feeding rates every 7 days. Final weights after 180 days were 512 g versus 645 g for power vs natural logarithm combinations, respectively. In Kentucky, field demonstrations (Wurts and Wynne 1995) indicated an increase in channel catfish body weight from 45 to 590 g in 175 days. Therefore, the mean weight determined from the field demonstration falls between the values calculated with the equations. Kentucky field observations suggest that precision feeding with equations could increase the accuracy of feeding and improve channel growth. Perhaps one of the other two possible combinations of the power and natural logarithm equations more accurately represent actual channel catfish growth. More research in this area is needed. Perhaps channel catfish in four experimental treatments could be fed using each of the four possible equation combinations. Actual measurements of FCR, and % BW fed and weight gains at regular intervals could be used to refine and create more accurate tables and/or equations. Tightly grading fish size before stocking could fine-tune the effective use of equations even further. Feed can be as much as 50 percent of channel catfish production costs. Overfeeding creates higher waste loads in the aquatic production environment. As production practices continue to crowd more fish into smaller volumes of water and space, precise and accurate feeding practices are imperative to ensure profits by improving fish growth, health and survival. Notes William A. Wurts, Kentucky State University, College of Agriculture Food Science and Sustainability, UKREC, P.O. Box 469, Princeton, KY 42445-0469 www2.ca.uky.edu/wkrec/Wurtspage.htm References Robinson, E.H., M.H. Li, and M.W. Brunson. 1998. Feeding catfish in commercial ponds. Southern Regional Aquaculture Center, Publication No. 181 (first version no longer in print). Wurts, W.A. 2014. Channel catfish Ictalurus punctatus food conversion ratios, feeding rates and growth. Page 555 In: Aquaculture America 2014 in Seattle, WA. Book of Abstracts. Wurts, W.A. 2001. Review of feeding practices for channel catfish production. World Aquaculture 32(4): 16-17, 68. Wurts, W.A. and F. Wynne. 1995. Sustainable channel catfish farming: low management production through modified stocking and feeding practices. World Aquaculture 26(3):54-59. 7 Goodwin Drive ▪ Festus, MO 63028 USA ▪ 636-937-8830 Next-Gen Cutter Hub Systems Precision Dies and Cutters Rear Seal Systems Stabilization Systems Back Pressure Valve and Sanitary Start-Up Discharge Systems Carbide Protected Screws Leaders in Extruder Solutions for Optimization, Sanitation, and Safety See Us at Booth 109 for AQ 2016 in Las Vegas www.everextruder.com Rapid Die Exchange System Copywright © 2015 EEX-ADS-40042-11-2015 Field observations suggest that precision feeding with equations could increase the accuracy of feeding and improve channel growth.
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