NUTRITION AND FEED DEVELOPMENT FOR WARM WATER AQUACULTURE
Location: Aquatic Animal Health Research
Title: Enhancement effects of dietary wheat distiller's dried grains with solubles on growth, immunity, and resistance to Edwardsiella ictaluri challenge of channel catfish, Ictalurus punctatus
Submitted to: Journal of the World Aquaculture Society
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: May 15, 2012
Publication Date: December 10, 2012
Citation: Li, E., Lim, C.E., Cai, C., Klesius, P.H. 2012. Enhancement effects of dietary wheat distiller's dried grains with solubles on growth, immunity, and resistance to Edwardsiella ictaluri challenge of channel catfish, Ictalurus punctatus. Journal of the World Aquaculture Society. 43(6):814-827.
Interpretive Summary: Distiller’s dried grains with solubles (DDGS), the main by-product of the ethanol production that is produced after fermentation of dry-milled grains to ethanol, is readily available and its cost on a protein basis is lower than those of commonly used protein ingredients. Research evaluating the nutritional value of DDGS showed that 30% DDGS derived from corn can be included in tilapia or catfish diets without requiring lysine supplementation. With supplementation of lysine, DDGS at levels of 40% or higher can be used without affecting growth performance and feed utilization efficiency. DDGS also contain yeast, a rich source of beta glucan and nucleotides that have been reported to improve growth, immune responses and the resistance of fish to microbial infections. Wheat DDGS differs markedly in nutrient composition from corn DDGS, but no information is available on its nutritional value or use in channel catfish diets. Thus, this study was conducted to evaluate the influence of dietary levels of wheat DDGS on growth performance, immune responses, and resistance of channel catfish to Edwardsiella ictaluri challenge. We found that 20% wheat DDGS can be included in the diet of juvenile channel catfish as a replacement of a SBM and CM mixture on an equal protein basis without requiring lysine supplementation. With lysine supplementation, at least 40% WDDGS (highest level evaluated) can be used. Weight gain and feed utilization efficiency generally improved at these recommended inclusion levels of wheat DDGS. Inclusion of 30 or 40% WDDGS without lysine supplementation resulted in the development of anemia and decrease body protein content. Body fat, however, tended to increase in fish fed WDDGS-containing diets. The resistance to E. ictaluri infection increased in fish fed diets containing wheat DDGS regardless of lysine supplementation, but higher survival was obtained at wheat DDGS inclusion levels of 20% or higher. Serum complement and antibody production were significantly affected by dietary treatments, but did not appear to follow the trend of survival observed 21 days following bacterial challenge. The improvement in growth, feed utilization efficiency and resistance of fish to E. ictaluri infection obtained in this study may be due to the presence of brewers yeast and its subcomponents, such as ß-glucan and nucleotides, in the soluble portion of wheat DDGS.
Juvenile channel catfish were fed for 12 weeks with diets containing wheat distiller’s dried grains with solubles (WDDGS) at levels of 0 (diet 1), 10, 20, 30 and 40% without (diets 2-5) or with (diets 6-9) lysine supplementation as substitutes of soybean and corn meal mixture. Fish fed diet 5 had the lowest weight gain (WG), feed efficiency ratio (FER), protein efficiency ratio (PER), feed intake (FI) and survival. Fish fed diets 7-9 had significantly higher WG, FER and PER than fish fed diet 1. Body protein decreased in fish fed diets 4 and 5, while body lipid tended to increase in fish fed WDDGS-containing diets. Fish fed diet 5 developed anemia. The number of days to first mortality was delayed and cumulative mortality 21 days post challenge with Edwardsiella ictaluri was lower in fish fed WDDGS-containing diets relative to fish fed diet 1. Further decrease in mortality was obtained in fish fed diets with 20 to 40% WDDGS regardless of lysine supplementation. Serum protein, immunoglobulin and lysozyme were unaffected by dietary treatments. Serum complement and antibody titer against E. ictaluri significantly differed among treatments but did not appear to be related to cumulative mortality following experimental challenge.