Despite the promising amino-acid profile of soybean meal , inflammatory reactions arising from its inclusion in aquafeeds becomes a limiting factor to increased utilization of this alternative plant-based ingredient in salmonids . Numerous anti-nutritional factors commonly present in plant-based ingredients have been recognized and studied as potential c auses for the inflammatory effects related to soy-induced distal enteritis. Efforts to address poor performance using plant-based diets include selection in a strain of rainbow trout (Oncorhynchus mykiss) on a 100% plant-meal based feed containing 19.6% SBM and 25.6% soy protein concentrate. In addition to improved growth performance, this selected strain has shown concomitant resistance to the development of distal enteritis and evidence of increased oral tolerance to SBM. Several recent collaborative studies between the Hagerman Fish Culture Experiment Station and Bozeman Fish Technology Center highlight work that has been done to characterize soybean meal induced distal enteritis and develop a clinical model for early detection, progression, and amelioration of adverse effects.
Resistance to distal enteritis observed in the Hagerman selected-strain rainbow trout provide an excellent contrast and model for further characterization of acute mucosal inflammatory responses involving IL-17 paralogs, other interleukins, growth factors, calcium-binding proteins and other immunogenic markers . Additional studies have also characterized induction of T helper17 cells and the repression of T regulatory cells involved in oral tolerance as well as changes to gut histology and microbiota.