Exploring the nutritional value of corn fermented protein as a replacement for soybean meal in diets for juvenile channel catfish (Ictalurus punctatus): Impacts on production performance, intestinal health, and disease resistance

• Published in: Aquaculture 2024-06, Vol.587, p.740824, Article 740824
• Main Authors: Yamamoto, Fernando Y., Huang, Jing, Suarez-Barazeta, C. Camilo, Craig, Steven R., Older, Caitlin E., Richardson, Bradley M., Santana, Thiago M., Griffin, Matt J., Reifers, J. Grant, Goodman, Penelope M., Gatlin III, Delbert M.
• Format: Article
• Language: English
• Subjects: Alternative protein ingredient; Brewers' yeast; Distillers co-products; Intestinal microbiota
• ISSN: 0044-8486; 1873-5622
• DOI: 10.1016/j.aquaculture.2024.740824

The use of corn fermented protein (CFP) can be a promising alternative ingredient to replace soybean meal (SBM) in aquafeeds, because of its attractive price and constant supply. In this study, the apparent digestibility of CFP was evaluated with channel catfish (Ictalurus punctatus), followed by a comparative feeding trial in which dehulled, solvent extracted SBM in the control diet was incrementally replaced with graded levels of CFP. A slight but significantly higher apparent protein digestibility coefficient was observed for SBM (91%) compared to CFP (89%). However, phosphorus and lipid were twice as available from CFP than SBM. A 60-day feeding trial was conducted, testing the gradual replacement of SBM by CFP on an equalnitrogen basis at 0, 25, 50, 75, and 100%. Channel catfish juveniles (∼11.6 g) were stocked in 30 aquaria (30 fish/ 110-L tank; n = 6) operating as a recirculating system and offered the experimental diets to apparent satiation twice daily. No differences were observed for hepatosomatic index, survival, or serum superoxide dismutase and lysozyme activities. Also, no treatment effects were observed for whole-body protein, ash, and protein conversion efficiency. However, weight gain, feed efficiency, intraperitoneal fat, and whole-body lipid were significantly affected by the dietary treatments with CFP able to replace up to 40 to 58% of the SBM in the diet while providing similar fish performance and body composition as fish fed the control diet. Digesta samples from the posterior segment of the intestine were subjected to DNA extraction, followed by 16S rRNA gene (V3-V4 region) sequencing to profile the intestinal microbiota. A higher relative abundance of Aeromonas spp. was observed for fish fed the control diet. The remaining fish from the feeding trial were challenged with Edwardsiella ictaluri, and cumulative survival was monitored for 21 days. Survival after the bacterial challenge gradually increased as the inclusion levels of CFP increased in the diets, with the 100% replacement treatment being significantly different from the control diet. In conclusion, CFP is a promising alternative plant protein ingredient with high protein and phosphorus digestibility, and it can replace up to 40 to 58% of the SBM in feed formulations for juvenile channel catfish based on weight gain and feed efficiency while potentially increasing disease resistance against E. ictaluri. •Corn fermented protein (CFP) yielded high nutrient digestibility for