Krill meal
Krill meal enhances health and fillet quality of Atlantic salmon, according to new study
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by Aker BioMarine, Norway
he wild fish harvested from the ocean and processed to become fish meal (FM) and fish oil (FO) are finite resources that are shared across a range of users with increasing demands, for direct human consumption, pig and poultry production, to aquaculture feeds (1; 2) (1, 2). Because of the high cost of fish meal and fish oil, due to increased demand and as mentioned limited resources, traditional small pelagic fish have also been increasingly replaced by vegetable feed ingredients in salmon feeds. For example, during the past two decades, the amount of fish included in feed ingredients has dropped dramatically from 65 percent to 18 percent for fish meal and from 24 percent to 11 percent for fish oil. However, farmed salmon remains a main user of both fish meal and fish oil so further complementary feed ingredients are required to support the salmon aquaculture market’s continue growth. There is an urgent need to find alternative feed resources that can further replace fish meal in Atlantic salmon diets, without compromising welfare and feed quality, in particular during the finishing feeding period when the feed demand is highest and flesh quality effects are most significant. Antarctic krill meal is considered a unique and genuinely sustainable raw ingredient, high in protein content, favourable amino acids and fatty acid profiles, and with enhanced palatability properties. It has also been suggested that the low molecular weight soluble compounds of krill meal, such as nucleotides, amino acids and high levels of trimethylamine N-oxide, all act together to make krill meal an effective attractant and flavoring agent. This has been confirmed in various species, such as salmon (3) resulting in a healthier and more robust farmed fish.
Krill meal as a feed ingredient for salmonids
Various aquafeed publications and scientific articles have examined krill meal’s proteins, palatability, pigment, heavy metals, dioxins and other important compounds and how krill impacts aqua feeds. Pages and pages of text show that Antarctic krill meal’s nutritional attributes make it a unique feed ingredient for aqua-feeds due to its unique protein quality, strong palatability, natural beta-carotene (in the form of astaxanthin), excellent lipid and minerals profile and its chitin and chitosan constituency. Krill meal’s negligible amount of dioxins, PCB’s and heavy metals are also a key asset when adding it to feed formulations. Krill meal is an excellent source of protein (average 60% dry basis) with an interesting profile of amino acids. Regarding palatability, krill meal has a low molecular weight of soluble compounds such as nucleotides, amino acids in the form of proline and glycine, glucosamine, and high levels of trimethyl amine oxide, TMAO. All of these act together as an effective attractant and flavouring agent. Krill meal’s high TMAO content has an extra osmoregulatory contribution, useful in reducing salmon’s physiological stress when they are transferred from fresh to seawater and it has also been successfully used in low palatability diets containing vegetable proteins and/or antibiotics. Antarctic krill meal’s natural pigment (in the form of astaxanthin) increases flesh pigmentation in salmon, trout, yellowtail, shrimp and other farmed species. Beta-carotene astaxanthin found in krill meal also plays an important role in the regulation of fish’s immune systems, enhancing disease resistance, boosting survival rates and acting as an essential fish growth regulator. Krill meal chitin content found in raw krill shell is typically at an average content of twoto-four percent of chitin and the resulting krill meal is used as an immune system stimulant in some fish species.
28 | July 2020 - International Aquafeed