Cows fed cannabis get high. And who drinks the milk?

The cows that consume cannabis get hungry and spend more time laughing with their stoned friends?

It might seem like the start of a bad joke, but German researchers trying to understand the effects of feeding dairy cows THC, the psychoactive compound found in industrial hemp, have made some intriguing discoveries, according to a study published this week in the journal Nature Food.

Compared with cows fed the standard corn and hay diet, hemp-fed Holstein cows were more relaxed, salivated and yawned more frequently, and often played fancy tongue games, the study found. They also spent more time lounging in the barn as they chewed and chewed on the universe.

They did not, however, exhibit a tendency toward binge eating.

While the behavioral changes were noteworthy, they were somewhat unforeseen consequences of an experiment carried out by researchers at the German Federal Institute for Risk Assessment, which aimed to find out how THC-laden hemp might affect dairy production. The scientists also wanted to know if THC (short for tetrahydrocannabinol) could reach humans through milk.

These questions are especially pertinent for American hemp growers, who have struggled to find an outlet for tons of leftover fibrous material after cannabinoid compounds like CBD are extracted from the plant. Cannabis sativathe flowering plant that produces widely divergent levels of THC depending on the cultivar.

The main difference between hemp and marijuana is the level of THC—hemp cannot contain more than 0.3% THC. Long prized for its textile fibers and for making rope, hemp was banned in the 1930s during a spasm of anti-drug fervor that was well captured in the cult classic film “Reefer Madness”.

In the United States, Congress reversed the ban on growing hemp in 2018, which fueled the booming market for CBD oil and numerous products containing it, but hemp cannot legally be used as livestock feed.

“Hemp farmers are struggling to deal with tons of this unwanted biomass,” said Jonathan Miller, general counsel for the US Hemp Roundtable, an industry group.

The German study offers hope to growers and grounds for caution. The researchers found that the natural but limited levels of THC in most industrial hemp had no effect on the ten cows in the experiment. But when they fed the animals flower buds and leaves — parts of the hemp plant that contain higher concentrations of THC — the researchers found that the cows ate less and that milk production dropped significantly.

Perhaps more importantly, for humans at least, THC found its way into milk, sometimes at levels that exceeded consumption limits set by Europe’s food safety regulators. (The United States has no comparable standard. The Centers for Disease Control and Prevention advises new mothers to avoid marijuana and CBD products while breastfeeding, saying that research on the effects of mere traces on an infant remains unclear.)

That said, THC became undetectable shortly after hemp was removed from the cows’ diet. Apparent signs of intoxication, including reddened eyes, a runny nose and what the study authors described as an “unstable gait” and an “abnormal posture” disappeared two days after the cows went into withdrawal.

Robert Pieper, one of the study’s lead authors, said it was unclear whether the drop in milk production was caused by THC or by one or more of the dozens of other cannabinoids or chemicals found in hemp plants.

The findings are largely in line with other recent US studies involving hemp and cattle. Oregon State University researchers who fed hemp to sheep found small amounts of THC in the animal’s muscle and fat, but the chemical disappeared several weeks after hemp was removed from its diet.

Serkan Ates, an associate professor at the Oregon State College of Agricultural Sciences, said the studies he and his colleagues have done with sheep and dairy cows have convinced him that there are few downsides to introducing hemp into the diet of farm animals, especially to the increasing cost of conventional feed. “The nutritional value of hemp is very high, but most of it ends up in landfills or compost,” he said.

In studies done at Kansas State University, THC appeared in the plasma of hemp-fed cattle, but the researchers also found something unexpected: The animals were noticeably more relaxed, according to biomarkers that indicate stress levels. As in the German study, which recorded lower heart and respiratory rates in cows that consumed high levels of THC, the animals also spent more time lying next to their barnmates.

Michael Kleinhenz, an assistant professor of beef production medicine at Kansas State University who participated in the studies, said the findings suggest hemp impregnated with THC may have practical benefits. On the one hand, heifers that spend more time relaxing tend to gain more weight, but an ecstatic cow is also healthier, Kleinhenz said.

He cited preliminary research that suggests reducing stress can help to mitigate the effects of driving cattle through the final chapter of their lives, when they are loaded into trucks that take them to feedlots and slaughter. The experience is not pleasant and is often followed by a spike in respiratory illnesses and other health problems.

Kleinhenz said relieving that stressful journey with a little marijuana in the feed, so to speak, could make cows happier and improve bottom lines for farmers. “Whenever we make things better for the animal, we win.”