Researchers tested whether giving dairy cows a special supplement called DHA (a healthy fat found in fish and algae) would improve their milk and health. Eight cows received different amounts of this supplement for short periods. While the supplement didn’t increase how much milk the cows produced, it successfully increased the amount of healthy DHA fat in their milk and blood. The cows also showed signs of better udder health. This research suggests that DHA supplements could be a way to naturally boost the nutritional quality of milk without changing production amounts.

The Quick Take

  • What they studied: Whether giving dairy cows a special omega-3 supplement (DHA from algae oil) would change their milk quality, blood chemistry, and how much milk they produce
  • Who participated: Eight adult Holstein dairy cows that were in the middle of their milk-producing cycle (about 3 months into lactation), producing roughly 49 kg of milk per day
  • Key finding: The supplement successfully increased healthy DHA fats in the cows’ milk and blood in a dose-dependent way, but didn’t change the total amount of milk produced. Cows also showed improved udder health markers.
  • What it means for you: If you drink dairy milk, DHA supplementation of cows may eventually offer a way to get more omega-3 fatty acids from milk products. However, this was a short-term study in a small group of cows, so more research is needed before this becomes a common practice.

The Research Details

This study used eight dairy cows in what’s called a Latin square design, which is a special way to test different treatments fairly. Each cow received four different treatments (no supplement, or 2, 4, or 6 grams of DHA daily) for 11 days each, with 10-day breaks between treatments to let their bodies return to normal. The DHA came from algae oil mixed into a liquid suspension. Researchers collected milk and blood samples during the last four days of each treatment period to measure what changed.

The researchers used a special technique called abomasal infusion, which means they delivered the supplement directly into a specific part of the cow’s stomach (called the abomasum) through a tube. This method ensures the supplement reaches the right place in the digestive system and isn’t broken down by the cow’s rumen bacteria before it can be absorbed.

This approach is considered a gold-standard research method because it allows precise control of the dose and direct measurement of how much supplement actually gets absorbed into the bloodstream and milk.

Understanding how to safely increase omega-3 fatty acids in milk is important because many people don’t get enough of these healthy fats in their diet. By finding ways to boost DHA in milk naturally through cow nutrition, researchers could help improve the nutritional value of a food that many people consume regularly. The direct infusion method also helps scientists understand exactly how much DHA the cow’s body can use, which is valuable information for future feeding strategies.

This study has several strengths: it used a controlled experimental design with each cow serving as its own control, measurements were taken systematically, and the researchers used multiple statistical tests to check their results. However, the study only included eight cows and lasted only a few weeks, so the findings may not apply to all dairy cows or long-term use. The cows were also in a controlled research setting, not typical farm conditions.

What the Results Show

The most important finding was that increasing amounts of DHA supplement led to increasing amounts of DHA in the cows’ blood and milk. Specifically, DHA in the blood’s phospholipids (a type of fat) increased from 0.30 to 0.82 units as the dose went up. Similarly, DHA in milk fat increased from 0.01 to 0.08 units, and the total amount of DHA the cows produced in their milk each day increased from 0.19 to 1.18 grams.

Interestingly, despite these increases in healthy fats, the total amount of milk produced didn’t change. The cows still made about the same quantity of milk whether they received the supplement or not. This is actually good news because it means the supplement could boost milk quality without reducing milk quantity.

Another positive finding was that somatic cell count (a marker of udder health and infection) appeared to decrease with the supplement. Lower somatic cell counts suggest healthier udders with fewer bacteria, which is beneficial for both cow welfare and milk quality.

The researchers also found strong correlations between how much DHA the cows absorbed and how much appeared in their blood and milk, suggesting that blood or milk DHA levels could be used as reliable indicators of whether the supplement is actually being absorbed.

The study also measured other types of fatty acids in the milk and blood. Total omega-3 fatty acids (a broader category that includes DHA) increased slightly with supplementation, from 0.56 to 0.63 units. DHA also appeared in different forms in the blood—in triacylglycerols (energy-storage fats) and cholesterol esters—showing that the supplement was being distributed throughout the cow’s body and incorporated into various biological systems.

This research builds on previous studies showing that omega-3 supplements can be incorporated into dairy products. However, most previous work used different delivery methods or supplements. This study is notable for using direct abomasal infusion, which provides a clearer picture of how much DHA actually gets absorbed. The finding that milk production wasn’t reduced is consistent with some previous research but contradicts studies where very high doses of omega-3s decreased milk fat production, suggesting there may be an optimal dose range.

The study only included eight cows, which is a small number, so results may not apply to all dairy cows or different breeds. The treatment periods were short (11 days), so we don’t know if the benefits would continue if cows received the supplement for months or years. The study was conducted in a controlled research setting, not on typical farms, so real-world results might differ. Additionally, the supplement was delivered directly into the stomach through a tube, which isn’t how supplements would be given on actual farms—they would be mixed into feed, which might change how well they work. Finally, the study only measured short-term effects, so long-term impacts on cow health or milk quality over a full lactation cycle remain unknown.

The Bottom Line

Based on this research, DHA supplementation appears safe and effective at increasing omega-3 fatty acids in milk without reducing milk production (moderate confidence level). However, more research is needed on longer-term use, different cow breeds, and practical farm-based delivery methods before making widespread recommendations. If implemented, supplementation should be monitored through regular milk testing to ensure effectiveness.

Dairy farmers interested in producing higher-quality milk with more omega-3 fatty acids should pay attention to this research. Consumers who want more omega-3s in their diet and are willing to pay for premium milk products may also be interested. However, people with dairy allergies or those following vegan diets won’t benefit directly. Researchers studying animal nutrition and omega-3 supplementation should definitely review these findings.

Based on this study, DHA levels in milk increased within days of starting supplementation (the study measured changes after just 11 days). If this were implemented on farms, consumers could potentially see increased DHA in milk within weeks. However, the long-term effects on overall health from consuming this milk would take months or years to become apparent and would require separate human nutrition studies.

Want to Apply This Research?

  • If using a nutrition tracking app, users interested in omega-3 intake could log their daily dairy consumption and track estimated DHA intake. For dairy farmers using farm management apps, track the DHA supplementation dose given (in grams per day) and correlate it with monthly milk testing results showing DHA content.
  • For consumers: If DHA-enriched dairy products become available, users could add them to their daily nutrition tracking to monitor omega-3 intake. For farmers: Implement regular milk testing (monthly or quarterly) to verify that DHA supplementation is effectively increasing milk DHA content, and adjust feeding protocols based on results.
  • Establish a baseline milk DHA level through testing, then retest after 4-6 weeks of supplementation to confirm the supplement is working. For consumers, track total omega-3 intake from all sources (fish, supplements, enriched dairy) to ensure adequate intake. For farmers, maintain records of supplementation costs versus the premium price achievable for DHA-enriched milk to determine profitability.

This research describes an experimental study in dairy cows and should not be interpreted as medical advice for humans. While the findings suggest that DHA supplementation may increase omega-3 content in milk, consumers should consult with healthcare providers about their individual omega-3 needs. This study was conducted over a short time period in a controlled research setting with a small number of animals, so results may not apply to all dairy cows or farm conditions. Any decisions about supplementing dairy cow diets should be made in consultation with a veterinarian or animal nutritionist. The long-term health effects of consuming DHA-enriched milk in humans have not been studied and would require separate clinical research.