Feed ingredients are the most critical drivers of all environmental impacts in shrimp aquaculture. The use of conventional raw materials contributes to overexploitation of natural resources and may compete directly with human food supplies. Utilizing locally sourced by-products as feed ingredients offers a sustainable alternative by reducing waste, recycling nutrients, adding value, and promoting circularity of the aquaculture industry. In this work, so far underutilized by-products of several industries in northern Germany were identified, biochemically characterized, and tested. Multiple feeding experiments were conducted in clear water recirculating aquaculture systems with the Pacific Whiteleg shrimp Penaeus vannamei.
In a first step, by-products from shrimp fisheries, insect farming, cosmetics, food, and beverage industries were biochemically characterized and the digestibility of key nutrients was determined in vivo (Figure 1).
Based on these findings, shrimp remains (Crangon crangon) and adult black soldier flies
(Imago, Hermetia illucens) were tested as a dietary protein source to replace fish meal (FM). Cocoons (H. illucens), algae pomace (Saccharina latissima), and carrot pomace (Daucus carota) were tested as functional ingredients to improve overall performance, health, and pigmentation of shrimp.
Shrimp remains improved growth and feed efficiencies at an optimal FM replacement of 85%. Adult black soldier flies suppressed growth of P. vannamei at all tested inclusion levels (13 – 26% of the feed). Cocoons and algae pomace significantly improved shrimp survival at a dietary inclusion of 5%. Dietary inclusion of 5% carrot pomace improved coloration of cooked shrimp but did not increase the total carotenoid and astaxanthin contents in hepatopancreas and uropods of shrimp. No adverse effects of any of the tested by-product were detected on hemolymph parameters (phenoloxidase activity, total hemocyte counts, plasma protein, plasma glucose) and digestive enzyme activities. Our results demonstrate that locally sourced by-products can be used as sources of protein, energy, and functional ingredient in shrimp feed formulations. The approach of utilizing side streams from traditional and emerging industries is transferable to many regions worldwide to enhance sustainability and profitability of aquaculture practices.