Krill is an important source of protein, omega-3 fatty acids and feed attractants for fish and shrimp. Here are some facts about krill and why it is so attractive in feed for shrimp and fish.
Facts on krill
- Krill is a shrimp-like swarming pelagic crustacean, which is used as a feed additive in diet formulations, mainly in the form of a high-protein krill meal.
- Krill is a feed attractant and shrimp and fish growth accelerator.
- Krill is a sustainable and pure alternative to fish meal and is characterized by a high content of omega-3 phospholipids.
- In shrimp farming, krill is given to improve yield and stress resistance without increasing production costs.
- In fish farming, krill not only increases yield, but also improves fillet quality and overall fish health.
Krill - a sustainable source
Krill is one of the most abundant species on earth with a biomass of around 500 million tons. The Commission for the Conservation of Antarctic Marine Living Resources (CCAMLR) restricts harvesting to a specific region in the Southern Ocean, Area 48, and to an annual krill harvest of 1% of the total biomass (the precautionary level for other fisheries is 10% of the total biomass). Aker BioMarine’s krill fishery has been certified by the Marine Stewardship Council (MSC) as being sustainable and 100% traceable.
Krill benefits and use
Due to its inherent advantages – i.e., feeding stimulants, omega-3 fatty acids bound to phospholipids, highly digestible peptides, naturally pure and stable, sourced sustainably – krill inclusion into shrimp and fish feed improves growth and yield. In particular, in diets low in fish meal, krill’s feed attractants increase palatability and improve growth performance. Moreover, krill is used in functional feeds for fish to increase fillet quality. Interestingly, reduced mortality and heart pathology during viral infection is seen in studies with salmon fed krill meal.
A continued sustainable growth of fish and shrimp farming
Continued growth of aquaculture and the change from small-scale to high intensity, industrial farming has increased the need for sustainable protein sources in both shrimp and fish feeds. However, fish meal supplies from wild-caught fish have stagnated.
A way to address the high demand and fish meal shortage is to replace fish meal with soybean meal, which increases cost effectiveness and sustainability of commercial feed. However, soybean meal has a different organoleptic profile than fish meal. Reduced palatability, as well as anti-nutritional factors causing low digestibility, can lead to impaired growth performance of shrimp and fish. Moreover, fish meal is of significant dietary value as a source of nutrients, including minerals and omega-3 long-chain fatty acids that are absent in soybean meal. In contrast to marine lecithins that contain omega-3 fatty acids in phospholipid form, soy lecithins are particularly rich in the pro-inflammatory omega-6 fatty acid, linoleic acid.
What nutrients does krill contain?
- Ca 60% protein with nutritionally well-balanced amino acids
- 25% lipids that are characterized by a high amount of phospholipids (around 40%)
- Omega-3 fatty acids (EPA and DHA)
- Astaxanthin esters
The antioxidant astaxanthin provides pigmentation and is known to have anti-inflammatory properties by the ability to scavenge free radicals, thereby counteracting oxidative stress and damage to proteins, lipids and DNA.
Moreover, krill meal is rich in chitin from the exoskeleton and soluble compounds like trimethylamine oxide (TMAO), free amino acids and nucleotides that may all act as feeding stimulants. Feeding stimulation by partial replacement of fish meal by krill meal in diets leads to increased growth of shrimp and fish, also seen to be true in situations of feeding depression (e.g. high vegetable diets) or stress conditions (e.g. change in salinity or temperature for shrimp and seawater transfer for salmon).
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