West Alabama (AL) catfish farmers employ various approaches for feeding catfish during the winter months with no set protocol regarding winter feed management. Farmers typically use daily satiation feedings during the growing season to maximize fish growth and maintain efficient feed conversion ratios. However, fish metabolism is greatly reduced during winter, drastically decreasing feed intake and growth rate. Catfish farmers use feed with 28% or 32% protein or a combination to feed their fish. Because of the uncertain winter feed management, this study aims to investigate different winter feed management strategies using the two feeds most used by the west AL catfish industry.
Two completely randomized trials were conducted with Channel catfish, Ictalurus punctatus, at two different sites. Trial A consisted of four treatments with three replicates, totaling 12 pond-based tanks of 2,495 L located at E.W. Shell Fisheries Center, Auburn University. Trial B comprised four treatments and four replicates, totaling 16 pond-based tanks of 800-L located on a Greensboro, AL, farm. The study treatments consisted of a 28% or a 32% crude protein feed fed either 4 times/month or 8 times/month throughout the winter. The feeding protocol consisted of checking the weather forecast, and fish were then offered feed on the warmest day(s) of a given week. A feed response was observed to feed the set rate of 1% of body weight/day. Water temperature and dissolved oxygen concentrations were measured daily; alkalinity, hardness, ammonia, and nitrite were measured weekly. Channel catfish with an average weight of 519.51 ± 7.23 g (trial A; mean ± SE) and 506.09 ± 2.38 g (trial B) were stocked in mid-January with water temperatures ranging from 3.3 to 23.2 °C (5.5 ± 1.6 °C). No feeding activity was recorded until mid-February, when water temperature ranged from 10.8 to 15.4 °C (12.9 ± 0.1 °C).
Preliminary results showed differences among treatments in some growth performance and proximate composition parameters. Individual final body weight was higher in fish fed 8 times/month (0.57 ± 0.02 kg) compared to fish fed 4 times/month (0.53 ± 0.01 kg; F1,12 = 5.12, P = .0430) in trial B, regardless of feed protein content. Whole body crude protein in trial A was higher in fish fed the 32% protein 8 times/month than in fish fed the 28% protein feed 4 times/month (t(8) = 4.1, P = .0140). Hematological analyses showed higher flesh phosphorus and amylase enzyme in both trials in fish fed 8 times/month compared to those fed 4 times/month, regardless of feed protein content. Alkaline phosphatase and alanine aminotransferase were higher in fish fed the 32% protein diet compared to the 28% protein diet in trials A and B, respectively. Preliminary results suggest changes in production, digestion, and modulation of nutrients from diets containing different percentages of crude protein. Further fatty acid composition and innate immune responses analyses could potentially provide more conclusive results.