Feeding Lambs Hemp Oil Creates a Nutritional Tradeoff

Hemp Seed Oil Improves Lamb Nutrition but Shortens Shelf Life

Hemp seed oil can change the nutritional composition of lamb without noticeably affecting its basic meat quality. The complication is that these nutritional gains may make the meat more vulnerable to oxidation while sitting in a refrigerated display.

A study published in Meat Science¹ tested hemp seed oil as a functional ingredient in finishing diets for lambs. The researchers found that it increased several classes of polyunsaturated fatty acids in the meat while leaving characteristics such as protein content, moisture, pH, drip loss, and tenderness largely unchanged.

However, hemp seed oil did not deliver the antioxidant protection the researchers had anticipated. During nine days of simulated retail display, meat from hemp-fed lambs became more susceptible to lipid oxidation than meat from lambs receiving canola oil.

The result presents hemp producers and the livestock industry with a revealing tradeoff. Hemp seed oil may help create meat with a more desirable fatty-acid profile, but using it commercially could require additional preservation strategies to keep that meat appealing throughout its retail life.

How Researchers Tested Hemp Seed Oil in Lamb Feed

The researchers used 40 four-month-old Dohne Merino lambs, dividing them among four finishing diets. One group received a conventional control diet with no added oil. The other groups received either 2.5% canola oil, 2.5% hemp seed oil, or 5% hemp seed oil.

The oils replaced maize grain on a one-to-one basis. After a 14-day adaptation period, the lambs remained on their assigned diets for 42 days. Researchers then examined growth, carcass characteristics, meat composition, fatty acids, colour, antioxidant capacity, oxidation, and tenderness.

The hemp seed oil itself contained polyunsaturated fats alongside tocopherols, terpenes, flavonoids, and several cannabinoids. That combination created an interesting scientific question. Polyunsaturated fatty acids can improve nutritional composition, but their chemical structure also makes them vulnerable to oxidation. Hemp phytochemicals might theoretically counteract that vulnerability by providing antioxidant activity.

The experiment was therefore testing more than whether lambs could consume hemp oil. It examined whether hemp’s fats and protective compounds could remain in balance after digestion, metabolism, slaughter, storage, and retail display.

Hemp Oil Changed Fat Composition Without Disrupting Meat Quality

Increasing the amount of hemp seed oil produced a clear rise in total polyunsaturated fatty acids, omega-3 fatty acids, omega-6 fatty acids, and conjugated linoleic acid in the lamb. Total saturated fatty acids did not change significantly.

The 5% hemp diet produced the most pronounced result. Total polyunsaturated fatty acids reached 5.77 milligrams per gram of meat, compared with 3.75 milligrams in the control group. Omega-3 content increased from 2.06 to 3.28 milligrams per gram, while conjugated linoleic acid increased from 1.28 to 2.15 milligrams per gram.

These findings demonstrate that at least part of hemp seed oil’s fatty-acid profile survived the ruminant digestive system and became incorporated into muscle tissue. That is not guaranteed because microbes in the rumen extensively transform dietary fats before the animal absorbs them.

Importantly, these changes did not come with an obvious decline in basic meat composition. Hemp supplementation did not significantly alter moisture, protein, ash, intramuscular fat, pH, or drip loss. Increasing hemp oil was also associated with lower thawing loss, although the practical value of that result requires further investigation.

The findings add a livestock dimension to hemp’s potential role in circular food systems. Oil, seed cake, hulls, and other processing fractions could provide additional revenue streams if researchers and regulators can establish safe, productive uses for them.

The Shelf-Life Tradeoff

The same polyunsaturated fats that made the meat nutritionally interesting also created its primary weakness. These fats contain multiple reactive sites that can be attacked by oxygen. Exposure to light, air, and refrigerated storage can initiate a chain reaction that produces undesirable flavours, odours, and colour changes.

Researchers monitored the lamb for nine days under illuminated retail-display conditions. By the final day, meat from the control and hemp groups had higher levels of thiobarbituric acid reactive substances, a standard indicator of lipid oxidation, than the canola group.

All four groups ultimately exceeded the commonly applied oxidative acceptability threshold of approximately 2 milligrams of malondialdehyde per kilogram of meat. The hemp treatments nevertheless performed worse than canola during the late stage of display. Canola oil’s greater proportion of monounsaturated fat may have made that meat less vulnerable to oxidative deterioration.

The hemp-fed lamb also showed a peak in metmyoglobin on day seven. Metmyoglobin is the oxidized pigment associated with the brown colour consumers often interpret as a sign that meat is no longer fresh. Its presence does not automatically mean the product is unsafe, but visible browning can shorten its commercially useful life by discouraging purchases.

Why Hemp’s Antioxidants Were Not Enough

Hemp seed oil contains tocopherols and other compounds associated with antioxidant activity. Its terpenes are also being investigated for uses extending from food preservation to renewable industrial ingredients. Yet the lamb study found no meaningful dietary improvement in the meat’s measured antioxidant capacity.

There are several possible explanations:

• Hemp antioxidants may have been present at insufficient concentrations.
• Digestion and metabolism may have transformed them before reaching muscle.
• The rise in polyunsaturated fat may have overwhelmed any protective effect.
• Processing or storage may have degraded some compounds before consumption.

The study did not measure the absorption or deposition of individual hemp-derived compounds in muscle. It therefore cannot determine precisely which phytochemicals reached the meat or whether their metabolites retained antioxidant activity.

This limitation reflects a broader challenge identified in a recent review of industrial hemp byproducts in ruminant diets. A feed ingredient can contain valuable compounds without delivering those compounds intact to meat or milk. The rumen, intestine, liver, and other tissues can transform them substantially along the way.

Better Nutrition Does Not Automatically Mean a Better Product

The study illustrates why food quality cannot be reduced to a single nutritional measurement. Increasing omega-3 and other polyunsaturated fats may look favourable on paper, but commercial meat must also retain its colour, flavour, texture, and stability long enough to move through processing, distribution, retail, and household storage.

That does not make hemp seed oil unsuitable for livestock. Instead, it suggests that feed formulation and post-slaughter preservation must be developed together. Producers cannot modify the animal’s diet while treating packaging and shelf life as unrelated problems.

Potential solutions could include pairing hemp oil with complementary dietary antioxidants, optimizing the dose, limiting oxygen exposure, using modified-atmosphere packaging, or shortening the period between processing and consumption. Each intervention would require testing because an antioxidant that performs well in feed may not remain bioavailable in muscle.

There is also a difference between hemp seed oil and lower-fat hemp byproducts. Seed cake or meal may supply protein, fibre, and residual oil without creating the same degree of oxidative pressure as concentrated oil. Future comparisons should examine whether these fractions deliver agricultural value with a more manageable shelf-life profile.

Regulation Remains Part of the Commercial Equation

Even strong nutritional results would not create an immediate global market for hemp livestock feed. Rules differ among jurisdictions, and regulators must consider animal health, cannabinoid residues, human exposure, and consistency between batches.

Canada defines industrial hemp according to a limit of no more than 0.3% THC in the flowering heads and leaves, as explained by Health Canada’s industrial hemp guidance. However, a crop’s classification as industrial hemp does not automatically authorize every derivative for every animal-feed application.

Research must therefore address both performance and traceability. Studies need to establish what animals consume, how hemp compounds are metabolized, whether residues enter edible tissues, and how the resulting food behaves during storage. These questions are particularly important when the feed contains measurable cannabinoids, even at concentrations far below those associated with intoxication.

Hemp Feed Research Is Entering a More Practical Phase

The central finding is not simply that hemp oil increased fatty acids in lamb. It is that the improvement exposed another constraint that must be solved before commercial adoption.

Hemp seed oil could be included at up to 5% of the tested finishing diet without materially damaging the lamb’s basic physicochemical qualities. It increased total polyunsaturated fats, omega-3s, omega-6s, and conjugated linoleic acid while leaving tenderness and major compositional measurements largely intact.

However, its antioxidants did not prevent late-stage oxidative deterioration. The next phase of research should test hemp oil alongside preservation technologies, quantify hemp-derived compounds in edible tissue, assess microbial stability, and include trained sensory panels or consumer tasting.

That would shift the question from whether hemp can be fed to livestock to whether it can support a product that is nutritionally appealing, commercially durable, economically viable, and acceptable to regulators. This study shows that hemp seed oil has potential, but it also shows exactly why potential alone is not enough.

References:

¹ Magqupu, S., Semwogerere, F., Marais, J., & Mapiye, C. (2027). Hemp seed oil-supplemented finisher diets for lambs: Impact on meat physicochemical quality and oxidative stability. Meat Science, 243, 110221. https://doi.org/10.1016/j.meatsci.2026.110221