A REVIEW ON THE USE OF KRILL MEAL IN SHRIMP FEEDS

Krill meal is a commercial product derived from Antarctic krill, Euphausia superba, a shrimp-like zooplankton practically unexploited and widely distributed in the cold waters of Antarctica. While its standing biomass ranges between 400 to 500 mmt, a precautionary catch limit was stipulated at 4 mmt. Fisheries currently harvest less than 0.1 mmt. In fishmeal-challenged shrimp diets, krill meal has been included between 2 and 5% to improve feed attractability and palatability and to promote shrimp growth. Its shrimp growth enhancement effect is partly explained by the supply of inorganic elements, balance of nutrients and its positive influence on feed intake. A typical krill meal can contain up to 65.0% of crude protein (CP), 22.0% lipid, 13.0% phospholipids, 5.0% chitin, and 0.6 mg/kg of cholesterol. Krill meal is rich in n-3 highly polyunsaturated fatty acids (DHA and EPA present at 5.5% of the meal), with levels of sulfur amino acids superior to those of high-grade fishmeal. This work presents a review on studies carried out at LABOMAR on the use of krill meal in grower diets for marine shrimp, illustrating approaches in formulation towards less marine-dependent and more effective feeds.

Studies focused on the use of krill meal to: (1) replace costly ingredients in shrimp feeds, including fishmeal, soybean lecithin, cholesterol, and fish oil, and (2) enhance feed intake and accelerate shrimp growth in fishmeal-challenged diets. All studies were conducted with juvenile whiteleg shrimp, Litopenaeus vannamei. Shrimp were farmed in two experimental rearing systems: (1) in circular tanks of 0.5 m³ under clear water and continuous water recirculation and filtration, and (2) in circular outdoor tanks of 1 m³ under green water conditions. In each study, 4 to 5 replicate tanks were designated per dietary treatment.

Under green and clear water rearing systems, krill meal has been able to effectively replace fishmeal and expensive lipid sources in white shrimp diets. Compared to eight other sources of proteins (soybean meal, soy protein concentrate, poultry by-product meal, meat and bone meal, feather meal, blood meal, tilapia meal, salmon meal), krill meal was able to promote the highest growth rate and final body weight in juvenile L. vannamei. In fishmeal-challenged and in plant-based diets (Fig. 1), krill meal enhanced shrimp feed intake, FCR, growth rate and final body weight staring at 2.0% of the diet (as is basis). Data have demonstrated that it is possible to reduce formula cost and accelerate the growth of whiteleg shrimp through low dietary inclusions of krill meal, even when adopting diets with little or no use of fishmeal and high levels of plant proteins.