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“Sphere-ized” aquatic feed By Dana Nelson, Aquaculture Specialist, Extru-Tech Inc Global aquaculture continues to grow and mature; production has increased both regionally and globally in recent years. Experts predicted this growth, and most have also concluded that aquaculture will provide a reliable supply of seafood in the future. However, issues related to food safety, nutrition, and sustainability, as well as a significant list of additional challenges, have become increasingly apparent. Fish nutrition and feed technology are a critical cog in the gears responsible for pushing aquaculture forward. Much of aquaculture’s success and failure worldwide is dictated by the challenge of cost-effectively compounding raw materials into a form that is readily acceptable for each stage of the aquatic species life cycle. Although most of the world’s starter aquafeeds are still produced by breaking larger pelleted and extruded feeds into smaller pieces and screening them into the desired sizes, more and more feeds are being extruded directly to their desired sizes. This trend is attributable to many factors. Newly emerging species require different
feeds. However, the shift has also been due in part to better understanding and analysis. Feed production costs are well understood by modern producers. It is becoming increasingly obvious that the advantages of crumbling feed are hamstrung by a few significant realities. First, even the most efficient crumbling lines require reprocessing of under- and oversized particles. This additional processing increases cost and damages nutrients. Second, the rough texture of crushed pellets can adversely affect palatability. Palatability remains as a performance factor with even the most developed species, and a critical one with others. Finally, and perhaps most importantly, producers’ awareness of the requirement to properly reduce the individual ingredients to ensure that they are sufficiently small to be contained in each particle of crumbled feed has led to significant improvements in grinding and mixing processes. This understanding has altered perspectives on formulations and the large particles that plague directly extruding
rations to the desired sizes in one step. These changes and other manufacturing advancements have encouraged manufacturers to reexamine their ability to directly extrude fine pellets.
History Over two decades ago, the limitations of using live feeds and traditional dry crumbles led Dr. Rick Barrows of the then United States Fish and Wildlife Fish Technology Center in Bozeman, Montana, to think outside the box. Dr. Barrows adapted pharmaceutical manufacturing equipment to produce micro-extrusion marumerization (MEM) feed. These openformula larval diets were used in fisheries restoration programs for walleye and other species. MEM is a “batch” process that involves atypical steps to normal aquatic feed production. Once raw materials are sufficiently ground, the ration is mixed with oil and water. The mix is then introduced
