Feed mills are rapidly moving towards shrimp diets with low fishmeal levels driven by the need to strengthen sustainability and economic parameters. Fishmeal replacement by plant and rendered animal proteins requires attention to nutrient composition and their bioavailaibility, so that proper dietary supplementation with amino acids, fatty acids, minerals and vitamins are carried out. In shrimp feeds, attractability and palatability also play a key role. Shrimp are slow feeders with a poor vision, thus relying on low molecular weight soluble compounds to detect and move towards a food source, and to initiate and remain feeding. Feed attractiveness has the potential to reduce leaching of nutrients, increase feed intake and prolong feeding activity. This work presents a review on studies carried out with juveniles of the whiteleg shrimp, Litopenaeus vannamei, fed minimum level or fishmeal-free diets containing low inclusions of krill meal (Qrill™ Antarctic krill meal, Aker Biomarine Antarctic AS, Oslo, Norway).
In Study 1, shrimp were stocked in 25 clear and green water tanks of 0.5 and 1 m3 under 100 and 60 animals/m2, respectively. A basal diet was formulated to contain 18.75% fishmeal, 2% fish oil, 1.5% soybean lecithin, and 0.15% cholesterol. From the basal diet, three other diets were prepared to include krill meal at 1, 5 or 11% by replacing fishmeal, fish oil, soy lecithin and cholesterol. After 72 days, shrimp showed no differences in performance among dietary treatments. In clear water, shrimp attained 13.1 ± 0.59 g body weight (BW), 1.00 ± 0.06 g/week, and 81.4 ± 7.3% survival. In green water, shrimp attained 14.3 ± 0.81 g BW, 1.04 ± 0.09 g/week, and 91.4 ± 5.4% survival. Diets containing krill meal were able to fully replace the protein and lipid value of the basal diet. In Study 2, shrimp of 1.13 ± 0.19 g BW were stocked in 30 green-water tanks of 1 m3 under 100 animals/m2 and raised for 71 days (37 ± 1.8 ppt salinity). A control (CTL) feed was formulated to contain 15% fish meal with 1% squid meal. Three other feeds were prepared by reducing the fish meal in the CTL by half (from 15 to 7%) and supplementing it with 1, 3 and 5% krill meal. Shrimp fed the CTL (8.14 ± 1.07g) and the feed with 5% krill meal (8.11 ± 1.18 g) achieved statistically higher BWs compared to other fish meal-challenged feeds. In Study 3, diets with 5.0% fishmeal, 7.75% soy protein concentrate (SPC) and between 13.1 and 15.0% poultry meal were supplemented with a combination of krill meal and squid meal included at 0.5, 1 and 2% of the diet. Shrimp were reared for 30 days in 20 clear-water tanks of 0.5 m3. Shrimp were stocked with 3.95 ± 0.67 g BW at 70 animals/m2. At harvest, there was a significant increment in shrimp BW when a combination of 2% krill and squid meal (7.90 ± 1.25 g) was used compared with a diet deprived of these ingredients (7.52 ± 1.17 g). In Study 4, krill meal was included at 0, 0.5, 1, 2 and 3% in all plant-protein based diets. Shrimp of 2.84 ± 0.52 g (n = 800) were raised for 72 days in 20 clear-water tanks of 0.5 m3 under 70 animals/m2. There was a significant improvement in shrimp growth, gained yield, feed intake and FCR when krill meal was used in plant-based diets at inclusion levels above 1%. However, shrimp BW was only improved at a dietary inclusion of 2% krill meal. At this level, BW increased from 12.13 ± 1.97 (1% krill) to 13.12 ± 1.88 g. This study demonstrated that krill meal in fishmeal-free diets enhanced feed intake at only 1%, while at 2% krill meal accelerated shrimp growth, while increasing yield and reducing FCR.