Hemp May Get Cows High, But Will Their Milk Do The Same To You?

By Deneen Broadnax

They were displaying the typical symptoms of being stoned: red eyes, wobbly gaits, and drowsy demeanors. But these weren’t people who had just frequented their local dispensary—they were cows.

In a new study, scientists report cattle that have eaten feed containing varying amounts of hemp seemed to get stoned like people do. The work may give regulators pause when considering whether the affordable, fast-growing crop is safe for livestock to eat. It also raises concerns about whether the active ingredient in marijuana can enter the human food supply through the milk of blazed bovines.

The behavioral effects documented in the new study are noteworthy, says Serkan Ates, an agronomist at Oregon State University, Corvallis, who has studied hemp consumption in cows, lambs, and chickens. “They found a much more profound effect on the animal’s behavior than what we’ve seen in any of our dairy-feeding studies.”

Derived from Cannabis sativa plants, hemp possesses a less potent concentration of the psychoactive compound tetrahydrocannabinol (THC) than marijuana-related varieties of cannabis. Instead, hemp flowers are loaded with cannabidiol (CBD), a chemical that has been linked to alleviating a slew of health issues such as anxiety, addiction, and insomnia. Additionally, hemp’s pliable fibers can be made into a variety of products such as clothing, shoes, paper, and biodegradable plastics.

The cultivation of hemp has exploded in recent years. However, the U.S. Food and Drug Administration has yet to approve feeding the now-widespread crop to cows because of concerns about THC entering the food supply.

To flesh out how hemp’s cannabinoids impact livestock, scientists at the German Federal Institute for Risk Assessment fed 10 lactating dairy cows differing amounts of hemp feed containing a range of cannabinoid concentrations. Over the course of the weekslong experiment, the researchers collected milk, blood, and fecal samples and paid close attention to the cattle’s behavior.

Dosage was key. Cattle that ate fermented feed formulated from whole hemp plants (which have a relatively lower concentration of cannabinoids) exhibited few noticeable changes from cows fed a normal corn-based diet. It was a different story for cows that consumed feed made from cannabinoid-rich hemp leaves, flowers, and seeds. By the scientists’ calculations, these cows consumed up to 86 times the amount of THC that’s required to get humans high. The animals’ breathing and heart rates slowed as they ate less and produced less milk.

The befuddled bovines also yawned more, produced more saliva and snot, and exhibited overactive tongues, the researchers report today in Nature Food. Some even exhibited reddening in their eye membranes and unsteady movements.

The unusual behaviors ceased a few days after the cattle stopped eating hemp. But the cannabinoids persisted in the cows’ milk, which contained elevated concentrations of THC, CBD, and other cannabinoids.

It remains unclear whether such milk would get human consumers high. “The study does not allow any conclusions to be drawn as to whether there is a health risk from consuming milk on the market,” says animal nutritionist and study co-author Robert Pieper.