In order to combat the increasing cost and environmental detriment of fishmeal (FM), plant protein sources have grown in popularity as a protein replacement in aquafeeds. Soybean meal (SBM) is one of the more notable protein alternatives due to its high protein content and relatively well-balanced amino acid profile. However, at high dietary inclusions, SBM has been found to have negative impacts on feed ingestion, digestion, and growth rates. This is primarily attributed to the presence of anti-nutritional factors that can lead to intestinal inflammation. Thus, the objective of this study was to investigate how alternating feeding regimen influences feed utilization and intestinal health of fish fed a high-inclusion SBM based diet.
Zebrafish Danio rerio was used as a model species. At 23 days-post-fertilization, fish were randomly stocked into 3.0 L tanks with 21 fish per tank. Each tank was randomly assigned to one of four treatment groups: fish fed with fishmeal-based diet (FM) every day (FM-FM), fish fed with soybean meal-based diet (SBM) every day (SBM-SBM), alternating FM and SBM daily (FM-SBM), and alternating FM and SBM weekly (FM/SBM). There were three replicate tanks per treatment group with a total of 12 tanks. Fish were fed to apparent satiation three times daily for four weeks.
There were no significant effects of feeding regimen treatment on survival, final average weight per fish, or FCR (p > 0.05). However, numerically, the FM/SBM group tended to have the highest average weight per fish (Table). The SBM-SBM group, presenting with the numerically lowest average weight, had higher relative expression of inflammatory gene tnfa (p < 0.05) compared to the FM-FM group (Figure).
Based on the minimal differences between the FM-FM and FM/SBM groups, alternating FM- and SBM-based diets weekly could represent a practical and cost-effective feeding regimen for fish with potential for applications in other species.