Buzz over hemp-fed cows
Study researches possibility of milk consumption leading to human exposure to THC
Do cows that consume cannabis act goofy, get the munchies and spend more time lolling about with their stoned buddies?
It may sound like the beginning of a bad joke, but German researchers seeking to understand the effects of feeding dairy cows THC, the psychoactive compound found in industrial hemp, made a few intriguing discoveries, according to a study published this week in the journal Nature Food.
Compared with cows that received the usual diet of corn and hay, the hemp-fed Holsteins were more chilled out, salivated and yawned more often, and frequently engaged in whimsical tongue play, the study found. They also spent more time lounging around the barn as they chewed their cud.
Although the behavioral changes were noteworthy, they were in some ways the unintended consequences of an experiment by researchers at the German Federal
Institute for Risk Assessment, who were seeking to learn how THC-laden hemp might affect dairy production. The scientists also wanted to know whether THC, short for tetrahydrocannabinol, could find its way to humans through milk.
Those questions are especially pertinent to American hemp growers, who have struggled to find an outlet for the tons of fibrous material left over once cannabinoid compounds like CBD are extracted from cannabis sativa, the 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% of THC. Long prized for its textile- and rope-making fibers, hemp was banned in the 1930s during a spasm of anti-drug fervor.
In the United States, Congress reversed the prohibition on hemp cultivation in 2018, which has fed the expanding market for CBD oil and myriad products containing it, but hemp cannot legally be fed to livestock.
The German study provides both hope for growers and reasons for caution. Researchers discovered that the naturally occurring but limited levels of THC in most industrial hemp had no effect on the 10 cows in the experiment. But when they fed the animals flower buds and leaves — parts of the hemp plant that contain higher concentrations of the THC — researchers found that the cows ate less and that milk production dropped significantly.
Perhaps more important, at least for humans, the THC made its way into their milk, sometimes at levels that exceeded consumption limits set by food safety regulators in Europe. (The United States has no comparable standard. The Centers for Disease Control and Prevention does advise new mothers to avoid marijuana and CBD products while breastfeeding, saying the research on the effects of passing even trace amounts to an infant remains unclear.)
That said, THC became undetectable soon after hemp was removed from the cows’ diet. Apparent signs of intoxication, including red-rimmed eyes, runny noses and what the study authors described as an “unsteady gait” and “abnormal posture” faded within two days.
Dr. Robert Pieper, a lead author of the study, said it was unclear whether the slump in milk output was caused by THC or perhaps by one or more of the dozens of other cannabinoids or chemicals found in hemp plants.