Sustainable sources of omega-3 fats for fi sh feeds

data can be used to evaluate the effects of an assortment of variables, such as rearing condition, feed, and genotype (family) to real-life production standards, providing feedback for broodstock advancement. Customized PIT tag antennas can be installed at the processing plants to automate the sorting of tagged and untagged fish for further data collection.

Biomark is a worldwide supplier of electronic identification and related monitoring systems to fish and wildlife conservation communities and the aquaculture industry. The company designs, manufactures, and markets novel radio frequency identification (RFID) technology for fish and wildlife, specialising in PIT tag technology used in a broad variety of identification and monitoring solutions. Through advanced technology, Biomark develops services that prioritise the short- and long-term health and sustainability of fish, wildlife, and aquaculture, designed to deliver quality data necessary for critical management decisions.

Biomark is an aquaculture portfolio of digital products within MSD Animal Health.

For more information, visit www. biomark.com

The tissue sampling unit can take a 3 mm fin or tissue notch and includes a liquid buffer to stabilise DNA and a transport medium.

Sustainable sources of omega-3 fats for fish feeds

Plants may be part of the solution

If the global expansion in aquaculture production is to continue, more sustainable sources of the omega-3 fatty acids required for the healthy growth of fish will be required.

Omega-3 fats are polyunsaturated fatty acids (PUFA) that are essential for the normal development of the human body. The best-known kinds of omega-3 fatty acids are EPA (eicosapentaenoic acid), DHA (docosahexaenoic acid) and ALA (alphalinolenic acid). These substances are, however, not produced by the body but need to be obtained from the diet. The importance of EPA and DHA has been confirmed by scientific studies dating back to the 1970s showing their impact on the development and health of the brain, eyes, and the cardiovascular system and there are official recommendations from national and international bodies for daily intake of omega-3 fats.

While ALA is found mainly in vegetable sources including walnuts,

Some additives to fish feed offer benefits to the fish, while other are intended to improve different properties of the feed.

flaxseed (linseed), rapeseed and their oils, and some green leafy vegetables, EPA and DHA are found in fatty fish such as salmon, mackerel, herring, sardines, and tuna. Eating oily fish is a way of obtaining recommended amounts of EPA and DHA. Fish in turn obtain these omega-3 fatty acids from their diets. Microalgae that float in the light-flooded, near-surface layers of the oceans are the original source of omega-3 fatty acids. In the marine food chains these fatty acids accumulate successively in zooplankton and then, in wild fish. Farmed fish, such as salmon, one of the richest sources of EPA and DHA for humans, obtain omega-3s from the fish oil component of their feed.

Genetic technologies to produce omega-3s from plants

Aquaculture production has been increasing steadily over the years and with it demand for fish oil and fishmeal, key components of fish feed. These ingredients are derived primarily from industrial fisheries, that is, catches of species not used for human consumption, but supplies of such fish cannot keep up with the demand. This constraint threatens the growth of the global aquaculture industry which uses almost three fourths of worldwide fish oil production. Although raw material for fish oil is now also obtained from the leftovers from processing operations and bycatches from the fishing industry, these sources are not expected to relieve the situation significantly. Sensing an opportunity companies have been exploring the possibility of producing omega-3-rich microalgae on a commercial scale and extracting the omega-3 fatty acids from them. Among the advantages of this source is that it has no impact on fish stocks. Companies are also trying other approaches. At Aquafeed Horizons, a webinar organised by aquafeed.com in February this year, Pablo Berner from Nuseed, an Australian company, reported on an omega-3 enriched variety of canola oil. Canola (Brassica napus) is a crop grown for its seeds that yield an edible oil. Nuseed, in collaboration with two Australian research bodies, the national science agency and the Grains Development and Research Corporation, has developed a canola that is rich in omega-3 fats using genetic breeding technologies to insert microalgae genes into canola plants. The company claims that one hectare of its omega canola provides the omega-3 fats corresponding to 10 tonnes of forage fish.

Describing three trials involving salmon in which 60, 50, and 30 of the fish oil was replaced with the Nuseed product, Mr Berner showed how the production parameters, growth, specific feed rate, and feed conversion ratios all improved. He attributed this to the product’s omega-3 profile which increased the total proportion of omega-3s in the diet thereby increasing fish health and welfare. It also led to increased total omega-3s in the salmon fillet thus potentially benefiting consumers too. Another positive change was the decline in mortality which was even more pronounced when the fish were subjected to a sanitary challenge. Including the product In feed formulations improved omega 6 to omega-3 ratios with a reduction in the use of fish oil. The fish farming industry is striving to further reduce its dependence on wild fish for feed, both in response to consumer demand, and to ensure the future of the sector itself. Plant proteins, products from meat

13 - 15 OCTOBER 2021 / AALBORG, DENMARK

WELCOME TO DANFISH INTERNATIONAL

Visit one of the most important exhibitions for equipment to the fishing industry. DanFish International takes place on 13-15 October.

VENUE

Aalborg Kongres & Kultur Center Europa Plads 4, 9000 Aalborg, Denmark

Olivier Decamp

Probiotics, live microorganisms, feed on prebiotics to give postbiotics, metabolites that promote the health and wellbeing of the animal.

rendering plants, insects, micro- and macroalgae, bacteria, and fungi are all being considered for their potential as ingredients for fish feed and many of them are already being deployed. Mr Berner’s figures showed a decline in the fish in fish out (FIFO) ratio, a measure of how much wild fish is needed to produce a unit of farmed fish, when using the Nuseed product, thereby contributing to the sustainability of the aquaculture sector.

Probiotics+prebiotics= postbiotics

Omega-3 fatty acids in fish feed contribute to the health and well being of the fish. Probiotics play a similar role. The intestines of higher organisms including fish and shrimp harbour billions of microbes that have a symbiotic relation with the host. In exchange for the nutrients they derive from the host’s gut, they help the host make more efficient use of some nutritious elements and assist in the defence against pathogens. In humans, these microorganisms, which include bacteria, fungi, protozoa, and viruses, help digest food, produce vitamins, and regulate the immune system. The microorganisms while generally beneficial also include some pathogenic types. Maintaining the balance between the two kinds is key to the health of the individual. Products promoting gut health include pre and probiotics which are widely used in the aquaculture industry. Probiotics are beneficial bacteria that are introduced to colonise the gut while a prebiotic is a food ingredient intended to stimulate the growth and activity of the microbial population in the intestines. At the Aquafeed Horizons webinar Derek Petry from Diamond V, a US-based manufacturer of feed additives for livestock, spoke about the company’s postbiotic for fish and shrimp. The interaction between the probiotics and the prebiotics results in postbiotics, metabolites that contribute to the health and well being of the animal. These can also be created exogenously, that is outside the body of the animal, in a manufacturing facility and then fed to the animal. Postbiotics may have some advantages over pre and probiotics. The latter must go through the harsh environment of the stomach before they can reach the intestines that they colonise. This passage may also be interrupted by medicines being administered to the animal, or stress. In addition, as the pre and postbiotics are vulnerable to different factors it can also result in variations in the postbiotics.

Diamond V creates a consistent and high quality metabolite. Different analyses test for consistency which is also measured by rigorously testing product composition and comparing it against a library of products. Performance testing confirms the expected performance. The product works by interacting with the animal’s innate immune system conferring a strong innate immunity and also by its impact on the adaptive immune system promoting rapid response and recovery, gut integrity, and digestive health. The product encourages the immune system to react to a threat quickly and at the appropriate level and then return to its usual state. Mr Petry stated that studies over the last decade, many of them published, show that average survival rates using the product are almost 12 percentage points higher than the controls and when the animals are challenged this increases to 27 points. The increase in survival rates was accompanied by a 5.3 increase in the growth rate and a decrease in the feed conversion ratio of 1.6. Similar results were obtained from a study carried out at the Kasetsart University in Bangkok.