Effect of Soy Protein Products and Gum Inclusion in Feed on Fecal Particle Size Profile of Rainbow Trout

Replacement of fishmeal (FM) with alternative plant proteins, especially soybean meal (SBM), can cause a diarrhea-like symptom in rainbow trout (RBT), characterized by very fine fecal particles. These fines do not settle out raceway effluent for collection and contribute to pollution receiving waters. In this study, two experiments were conducted. Experiment 1 examined effects nine protein sources (sardine meal, menhaden soy concentrates (SPC) (three types), SBM (regular high protein), corn concentrate (CPC), poultry by-product (PBM)) on particle size distribution. Results showed that all five soy-based diets produced feces RBT having 75.7–89.3% only about 1.0% large particles, while the remaining four yielded balanced Oligosaccharides present naturally products, thought fines, correlated classes. Instead, crude fiber content was found be responsible unbalanced distribution RBT. 2 if improvements formulation could reduce negative effect ingredients. Eight practical (FM, SPC, SPC + 0.3% guar gum, PBM CPC, CPC 20 or 30% gum) formulated contain 40% 20% lipid. containing mixtures PBM, plus gum highest percentage particles lowest diet alone (56%) resulted mid-size It concluded products (SBM SPC) caused undesirable profiles RBT, addition significantly alleviate effect.