Apparent Inability of Channel Catfish to Utilize Dietary Mono- and Disaccharides as Energy Sources

Abstract

Purified diets containing equivalent amounts of glucose, maltose, fructose, sucrose, corn starch and dextrin were fed to fingerling channel catfish (Icatalurus punctatus) to compare the growth responses to these various carbohydrates. The best growth response was achieved with dextrin and the next best with corn starch. Fish grew at the same rate when glucose, maltose or sucrose was the only dietary carbohydrate source. Dietary fructose resulted in the lowest growth rate. Feed efficiency and percent retained energy values followed the same pattern as growth rates. These data suggest that the catfish is apparently unable to utilize dietary mono- and disaccharides as energy sources. Oral carbohydrate tolerance tests using glucose, maltose, fructose, sucrose and dextrin were conducted with larger channel catfish. Oral glucose and maltose resulted in a persistent hyperglycemia indicative of a diabetic-like status. Fructose appeared to be poorly absorbed from the intestinal tract and did not appear to be converted to glucose. Oral administration of sucrose was followed by a gradual increase in plasma glucose, with no detectable fructose being absorbed until the 6-h period. Oral dextrin resulted in less than a two-fold increase in plasma glucose, which remained constant from 2 to 4 h after administration and then declined. These observations are consistent with the hypothesis that certain fishes, including the channel catfish, resemble diabetic animals by having insufficient insulin for maximum carbohydrate utilization.

Nutritional requirements of fish

“…In other species a requirement has been demonstrated only under somewhat unusual conditions, i.e. the use of water, free of Ca (Wilson, 1991).…”

Effect of feeding strategy and carbohydrate source on carbohydrate utilization by white sturgeon (Acipenser transmontanus) and hybrid tilapia (Oreochromis niloticus X O. aureus)

“…Common carp, red sea bream (Furuichi and Yone, 1982), tilapia (Anderson et al, 1984), yellowtail (Furuichi et al, 1986) and channel catfish (Wilson and Poe, 1987) grew better when fed a starch than glucose diet. On the other hand, chinook salmon (Buhler and Halver, 1961) grew better when fed a glucose than starch diet, and there was no significant difference in net weight gain between glucose and starch fed white sturgeon (Hung et al, 1989).…”

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“…However, dietary carbohydrate cannot be efficiently used by most aquatic animals compared with poultry and mammals (Wilson and Poe, 1987) and a high level of dietary carbohydrate may cause slow growth and other negative effects (Shiau et al, 1991). Nevertheless, carbohydrate is often included in the diet of aquatic animals as an energy source to spare protein and reduce feed cost in aquaculture (CruzSuarez et al, 1994;Cuzon et al, 2004).…”