PERFORMANCE OF RAINBOW TROUT Oncorhynchus mykiss FED CONVERTED SOY PRODUCTS

Defatted soybean meal, initially pretreated with thermo-mechanical methods, was microbially processed and formulated into experimental diets (25% soy inclusion) for a Rainbow Trout growth trial. The dietary treatments included a bioprocessed soy product (BP-SBM) without additions, BP-SBM with fungal cells, BP-SBM with fungal slurry, BP-SBM with enzyme, washed BP-SBM, base BP-SBM, and a fishmeal (FM) control diet. Performance measures including biomass gain, relative growth (RG), specific growth rate (SGR), feed conversion ratio (FCR), feed consumption, and condition factor were obtained at 3-week intervals during the 15-week trial. No significant differences were noted among growth parameters for the first 6 weeks of the study (p>0.05). RG (p=0.03) and SGR (p=0.03) significantly differed among treatments at the 9-week interval, while RG was the only parameter with a significant difference among treatments after 12 weeks (p=0.04). FCR was the only parameter that provided a significant response among treatments at the 15-week sampling (p=0.03). At the end of trial, 3 individuals per tank were randomly selected to assess hepatosomatic (HSI), splenosomatic, viscerosomatic and visceral fat indices, and fillet yield (%). HSI was the only index that significantly differed among treatments (p=0.04). This study indicates that health and growth performance are not inhibited when 46% of FM is replaced with microbially processed soy in the diets of Rainbow Trout.