Effects of processing full‐fat soya beans and fish trim for sustainable sablefishAnoplopoma fimbriafeeds

Abstract

To quantify the efficacy and cost of different soya protein ingredients, heated soya beans (HSB) and underprocessed (SB) full-fat soya beans (FFSB), soya protein concentrate (SPC) and trim waste from Pacific whiting (Merluccius productus) were incorporated into feeds for the cold water marine sablefish (Anoplopoma fimbria). Feed ingredients for this study were processed using an experimental heated ball mill with demonstrated potential as an affordable process for rural or small-scale feed production. The three feed treatments were formulated with equal amounts of soya protein and Pacific whiting process trim. The three feed treatments contained 46% protein and 18% lipid as dry matter. Three 480-L tanks of 10 fish were used to evaluate each of the three feed treatments. Fish were fed to satiation every 2 days for 8 weeks. Weight gain of the treatment groups ranged between 56% and 105% over the course of the study. Fish growth was significantly better among fish receiving the feeds containing HSB and SPC than a feed containing SB. At the conclusion of the study, histomorphologic evaluations of the distal intestines of final fish were conducted. Varying levels of inflammation were measured for all three treatments. Fisher's exact test showed a significant reduction in mononuclear cell infiltration among fish fed heat-treated full-fat soya beans vs those receiving underprocessed full-fat soya beans. Fish receiving HSB feed had significantly lower intestinal inflammation than SB fish. Based on our results, cost savings of $ 0.253/kg were calculated for the HSB feed over the SPC feed.