There is interest in increasing omega-3 content in eggs, meat, and dairy to improve their nutritional value and meet market demand. Many people eating a Western diet do not consume enough fish due to availability and cost, dietary preferences, or allergies.¹ Omega-3 enriched animal products are a convenient way for consumers to consume more omega-3s without significant dietary changes. Hopefully, research will continue on increasing omega-3 content in these products. Genetic engineering and/or selective breeding of livestock with better alpha-linolenic acid (ALA) conversion capacity may help this effort.

In some cases, omega-3 fatty acids are added to livestock diets for the direct benefit of the animal—not just the final product. Omega-3s are as essential to cattle, swine, poultry, and fish as they are to us. The addition of ALA from flaxseed into their diet will support overall health which, in turn, often leads to increased productivity.

Poultry

Milled flaxseed or flaxseed meal is often used as feed for laying hens because it increases omega-3 fatty acid content in their eggs. This is desirable because of human health benefits derived from omega-3 enriched eggs. It’s a “win-win” scenario because it’s an easy way for people to increase their omega-3 consumption, and it allows egg producers to differentiate their product in the market.

Feeding hens flaxseed also improves their health. One study² found that adding 50 to 100 g/kg flaxseed meal to the diet of laying hens improved the health status of their eggs for human consumption as well as their immune response. Another study³ evaluating the effects of ground vs whole flaxseed in diets of laying hens, found that levels of 10 to 15% flaxseed (both whole and ground) produced yolks with 4 to 7% omega-3 fatty acids. This would allow producers to label their eggs as “rich” sources of omega-3s. Bean and Larson⁴ found that when 10% flax was added to a laying hen ration, ALA increased from 38.5 to 306.3 mg/50g egg and DHA increased from 53.3 to 83.7 mg/50g egg.

Flaxseed supplementation also increases omega-3 content in the meat of broiler chickens and improves health indices for the birds.¹ However, care should be taken to not feed flaxseed for too long and/or at too high doses as this could have negative impacts on the oxidative stability in the meat.⁵ The maximum recommended inclusion rate of flax in broiler diets is 3%.¹ Adding enzymes to feed can improve the nutritive value of flaxseed for broiler chickens³ and pelleting the seed three times was found to increase fatty acid retention in the meat by 29%.¹

Dairy

There is tremendous potential for flaxseed in the dairy industry. Not only does flax provide macronutrients needed by dairy cows, but it also improves the nutrition of milk and milk products for human consumption. There is also evidence that flaxseed supports reproductive health and performance in dairy cows.⁶

Flaxseed is an excellent protein and energy source for ruminants, and it can be a good way for producers to increase energy intake in dairy cattle because it does not negatively affect rumen function like other oil sources.¹ Whole or ground flaxseed can be added to dairy cow diets because the seed coat provides protection for the fat. When too much fat is added to a ruminant diet, it can be damaging to fermentation process in the rumen.

Feeding flax to dairy cows increases the ALA content in milk.^6,7 However, due to microbial biohydrogenation, unsaturated fats do not typically make it past the rumen, resulting in milk that is not very rich in ALA despite supplementation.⁸ Putting flaxseed through a heat treatment can help to avoid biohydrogenation, resulting in milk with as high as 20% ALA content.⁹

Supplementing dairy cow rations with flaxseed can allow for production of dairy products that are superior from a human nutrition standpoint. It is well recognized that from both an evolutionary and a health perspective, consumption of omega-6 fatty acids in the Western diet is far too high. Furthermore, an increase in omega-3 consumption, which improves the omega-6:3 ratio, has been linked to the prevention or amelioration of numerous disease states. Saturated fat consumption is likewise quite high in the Western diet and linked to diseases such as cardiovascular disease, obesity, and more. Dairy products, which are naturally high in saturated fat, have been called “unhealthy” in recent years. Because dairy cows consume a lot of corn, soybean, and canola products, the omega 6:3 ratio in conventional milk is not ideal: around 5.77 (5.77 omega-6:1 omega-3) for conventional milk.¹⁰ Grass-fed milk and organic milk, on the other hand, have an omega 6:3 ratio around 0.95 and 2.28 respectively. Those ratios are much closer to the natural ratio on which humans evolved. Seeing as milk is a very common food in North American households, increasing the omega-3 content in milk and improving its omega-3 ratio, would provide big health benefits. Furthermore, supplementing with flaxseed is much cheaper than raising grass-fed, or even organic, dairy cattle. Flaxseed can also decrease saturated fat content in milk thereby increasing its benefit for human health.⁶

Beef

Flaxseed meal is an effective protein source for beef cattle of all stages in the production cycle and its high levels of energy and protein can increase feed intake and weight gain.¹ In some studies, supplementing with flax has been shown to increase carcass quality.^{1, 11} There is also research suggesting that ALA may enhance disease resistance in beef cattle.¹

One study¹² found that feeding 8% flaxseed to bull calves resulted in an increase of ALA from 3,200 mg to 9300g/100g of intramuscular fat. Once again, this is good news because it will allow for improved nutrition without the need for excessive changing of dietary patterns. Men’s Journal¹³ reported that consumers eat four times as much beef as fish. Although the amount of omega-3 in flax-fed beef is not as high as fish, the amount of beef consumed by North Americans means that this improvement could have a substantial impact. Grassfed beef is higher in ALA than conventional beef; however, the cost may be restrictive for many consumers. Flaxseed-supplemented beef could offer a middle ground in terms of cost.

Pork

Flaxseed supplementation in swine diets can improve sow productivity, piglet health, and result in juicier and tastier meat products.¹ Flax can be incorporated into the diet of grower and finisher pigs up to 10% and the addition of 5% flax may have long term reproductive benefits.¹

Supplementing pigs with flaxseed increases the omega-3 content in pork. One study found that feeding just 5% flaxseed increased omega-3 content enough to exceed the amount needed for an enrichment claim in Canada (300mg/100g serving) and showed a 4-fold increase over controls.¹⁴ This same study also found that when supplementing 5% and 10% flaxseed, the omega-6:3 ratio decreased by 6.8 and 12.4-fold respectively. Furthermore, it was found that when the adipose tissue deposits are left alongside lean pork cuts, EPA and DHA levels are high enough to make it a substantial source of these long chain omega-3s. Other studies on flaxseed supplementation in swine have likewise shown statistically significant increases in ALA, EPA, and DHA and decreases in monounsaturated and saturated fat without substantial negative effects on production efficiency or taste.^15,16,17

Aquaculture

Lipids are an important dietary component in aquaculture feed because they create a “protein sparing effect” which improves growth and protein deposition in fish.¹⁸ Lipids also supply essential fatty acids which are crucial for fish health. Fish meal and fish oil are important sources of high-quality omega-3 fatty acids in aquaculture production. However, part of the appeal of farmed fish is the reduced impact on wild fisheries, and there is currently a gap between supply and demand for fish meal and fish oil.¹⁸

The Food and Agriculture Organization of the United Nations (FAO) has stated that sustainability in the aquaculture industry will likely come from the replacement of fish meal and fish oil used for feed with plant products.¹⁹ Several studies have found that plant oils in aquatic feed need not come at the risk of decreased fish health or reduced fillet quality.^{20, 21, 22}

Seeing as flaxseed is the richest source of alpha-linolenic acid (ALA), a precursor to EPA and DHA, curiosity has been raised over its potential as a replacement for fish products in aquaculture feed. Fish, like mammals, can convert ALA into EPA and DHA. However, the efficiency of this conversion varies by species. Marine fish are far less efficient at synthesizing EPA/DHA from ALA than freshwater fish because they’ve evolved in an environment that does not require it.¹⁸ That said, several studies on replacement of fish oil with flax oil have been conducted with encouraging results.

As in humans and other mammals, the omega-6: omega-3 ratio is important for fish health. One study found that extensive replacement of fish oil with plant oils, particularly those high in linoleic acid (LA) caused a higher incidence of cardiovascular disorders in fish.¹⁸ There is also evidence from multiple trials that feed with a lower omega-6: omega-3 ratio resulted in a better immunity against pathogens.^{20, 23, 24, 25} It is apparent that when replacing fish derived lipids with plant sources, a low omega 6:3 ratio is crucial for fish health. This is good for flaxseed as it has the best ratio of all plant oils.

A different study found that supplementing rainbow trout with flaxseed oil at a rate of 0.5-1.5% for 9 weeks resulted in statistically significant improvement in growth, enhanced immune response, and lower oxidative damage.¹⁸ Another study examining flaxseed oil as a lipid source in the diet of fingerling rainbow trout, found that “fingerlings can be reared on diets in which fish oil has been replaced with flaxseed oil with no significant effects on fish performance.”²¹

The effect of a flaxseed oil-enhanced diet on the quality of brook trout fillets has also been researched.²² Results showed that the total omega-3 fatty acid content was higher in the flax fillets (P<0.05) and that sensory panelists preferred the flax fillets (P<0.05) over the fillets of fish supplemented with fish oil. All other quality parameters measured were the same between diet groups. This suggests that flax-enhanced diets for brook trout would have a net positive effect on fillet quality.

Notes

1.      Rex Newkirk PhD, “Flax Feed Industry Guide,” Flax Council of Canada, (2008)
2.      Tarek M. Shafey, Hamad A. Al-Batshan & Ahmed M.S. Farhan, “The Effect of Dietary Flaxseed Meal on Liver and Egg Yolk Fatty Acid Profiles, Immune Response and Antioxidant Status of Laying Hens,” Italian Journal of Animal Science 14, no. 3 (2015), doi: 10.4081/ijas.2015.3939
3.      S.E. Scheideler, G.W. Froning, “The Combined Influence of Dietary Flaxseed Variety, Level, Form, and Storage Conditions on Egg Production and Composition Among Vitamin E-Supplemented Hens” Poultry Science 75, no. 10 (1996): 1221-1226, doi: 10.3382/ps.0751221
4.      L.D. Bean, S. Leeson, “Long-Term Effects of Feeding Flaxseed on Performance and Egg Fatty Acid Composition of Brown and White Hens,” Poultry Science 82, no. 3 (2003): 388-394, doi: 10.1093/ps/82.3.388
5.      Kumar, et al. “Growth pattern, lipid composition, oxidation status, and serum biochemical profile of broiler chicken feed flaxseed meal for different durations.” Letters in Animal Biology 1, no. 1 (2021): 8-18, doi: 10.62310/liab.v1i1.54
6.      U. Moallem, H. Lehrer, L. Livshits, M. Zachut, “The effect of omega-3 a-linolenic acid from flaxseed oil supplemented to high-yielding dairy cows on production, health, and fertility,” Livestock Science 242, 2020, doi: 10.1016/j.livsci.2020.104302
7.      Maddock, T.D., Anderson, V.L., Lardy, G.P. “Using Flax in Livestock Diets,” NDSU Extension Service, February 2005, library.ndsu.edu
8.      Glenn Pizzey, “The Animal Industry as an Emerging New Market for Flaxseed,” in Complementary Therapies: A New Vision in Animal Health, Equine Research Centre, 2000
9.      C. Gonthier et al, “Feeding Micronized and extruded Flaxseed to Dairy Cows: Effects on Blood Parameters and Milk Fatty Acid Composition,” Journal of Dairy Science 88, no. 2 (2005):748-756, doi: 10.3168/jds.S0022-0302(05)72738-7
10.      Charles M. Benbrook et al, “Enhancing the fatty acid profile of milk through forage-based rations, with nutrition modeling of diet outcomes,” Food Sci Nutr. 6, no. 3 (2018): 681-70, doi: 10.1002%2Ffsn3.610
11.      C. Choi et al, “Effects of Rice Bran, Flax Seed, and Sunflower Seed on Growth Performance, Carcass Characteristics, Fatty Acid Composition, Free Amino Acid and Peptide Contents, and Sensory Evaluations of Native Korean Cattle (Hanwoo),” Asian-Australas J Anim Sci 29, no. 2 (2016): 195-203, doi: 10.5713%2Fajas.15.0264
12.      Y. Aharoni, A. Orlov, A. Brosh, “Effects of high-forage content and oilseed supplementation of fattening diets on conjugated linoleic acid (CLA) and trans fatty acid profiles of beef lipid fractions,” Anim Feed Sci Tech. 117, no. 1-2 (2004): 43-60, doi: 10.1016/j.anifeedsci.2004.07.019
13.      Brittany Smith, “Omega-3 Beef,” Men’s Journal, May 21, 2018, mensjournal.com
14.      T.D. Turner et al, “Flaxseed fed pork: n-3 fatty acid enrichment and contribution to dietary recommendations,” Meat Science 96, no. 1(2014): 541-547, doi: 10.1016/j.meatsci.2013.08.021
15.      John R. Romans, Duane M. Wulf, Roger C. Johnson, G.W. Libal, W. J. Costello, “Effects of ground flaxseed in swine diets on pig performance and on physical and sensory characteristics and omega-3 fatty acid content of pork: II. Duration of 15% dietary flaxseed,” Journal of Animal Science 73, no. 7 (1995): 1987-1999, doi: 10.2527/1995.7371987x
16.      Monica Tognocchi et al, “Linseed supplementation in the diet of fattening pigs: Effect on the fatty acid profile of different pork cuts,” Meat Science 204, 2023, doi: 10.1016/j.meatsci.2023.109276
17.      M. Okrouhlá, R. Stupka, J. Čitek, M. Šprysl, L. Brzobohatý, “Effect of dietary linseed supplementation on the performance, meat quality, and fatty acid profile of pigs,” Czech J. Anim. Sci. 58, no. 6 (2013):279-288, http://cjas.agriculturejournals.cz/pdfs/cjs/2013/06/05.pdf
18.      Hixon, S. M. “Fish Nutrition and Current Issues in Aquaculture: The Balance in Providing Safe and Nutritious Seafood, in an Environmentally Sustainable Manner,” J Aquac Res Development 5, no. 3 (2014), doi: 10.4172/2155-9546.1000234
19.      Food and Agriculture Organization of the United Nations, “FAO leads global efforts to strengthen aquaculture for food and sustainable development,” FAO Rome, May 17, 2023, fao.org
20.      Mohamed Omar Abdalla Salem, Yiğit Taştan, Soner Bilen, Ertugrul Terzi, Adem Yavuz Sönmez, “Dietary flaxseed (Linum usitatissimum) oil supplementation affects growth, oxidative stress, immune response, and diseases resistance in rainbow trout (Oncorhynchus mykiss),” Fish & Shellfish Immunology 138, 2023, doi: 10.1016/j.fsi.2023.108798
21.      A. Masiha et al, “Effect of dietary flaxseed oil level on the growth performance and fatty acid composition of fingerlings of rainbow trout, Oncorhynchus mykiss,” Springerplus 2, no. 1 (2013):1, doi: 10.1186/2193-1801-2-1
22.      C. A. Simmons et al, “The effect of a flaxseed oil-enhanced diet on the product quality of farmed brook trout (Salvelinus fontinalis) fillets,” J Food Sci. 76, no. 3 (2011): S192-7, doi: 10.1111/j.1750-3841.2011.02070.x
23.      M. Thompson, R. Lochmann, H. Phillips, T.D. Sink, “A dietary dairy/yeast prebiotic and flaxseed oil enhance growth, hematological and immunological parameters in channel catfish at a suboptimal temperature (15º C),” Animal 9, no. 7 (2025): 1113-1119, doi: 10.1017/S1751731115000300
24.      Y. Dong et al, “Dietary n-3/n-6 polyunsaturated fatty acid ratio modulates growth performance in spotted seabass (Lateolabrax maculatus) through regulating lipid metabolis, hepatic antioxidant capacity and intestinal health,” Anim. Nutr. 25, no. 14 (2023): 20-31, doi: 10.1016/j.aninu.2023.04.005
25.      Ian Car, Brett Glencross, Ester Santigosa, “The importance of essential fatty acids and their ratios in aquafeeds to enhance salmonid production, welfare, and human health,” Front. Anim. Sci. 4, 2023, doi: 10.3389/fanim.2023.1147081