Cows fed hemp produced milk with THC, researchers say

Dairy cows fed industrial hemp produced milk with detectable levels of the buzz-inducing molecular compound THC, according to a new study from Germany that could influence the potential uses of hemp as an ingredient in animal feed.

The dairy cows also showed behavioral changes – yawning and salivating a lot, moving a little unsteadily on their hoofs, standing in one place for a protracted period, and having a “somnolent appearance.”

The peer-reviewed study, conducted on Holstein cows in Berlin and published Monday in the journal Nature Food, is one of the first major investigations of the use of industrial hemp as a potential supplement in animal feed.

For now such use is illegal under United States law, which does not allow THC in the food chain. But the new research comes as hemp, which has many industrial uses, continues to emerge from an agricultural exile that dates to the “reefer madness” hysteria of the 1930s.

Hemp is the common name of the plant Cannabis sativa. Humans have cultivated it for thousands of years. Its fibers are prized in rope manufacturing, among many other uses. George Washington grew it at Mount Vernon in the late 1700s, and in recent years the estate has grown it anew.

The flowers of the cannabis plant have high concentrations of delta-9-tetrahydrocannabinol – THC. That’s the molecular compound that delivers a high to someone who smokes or consumes it. Hemp with high levels of THC is called “marihuana” in the curious spelling of the federal government, and remains a Schedule 1 substance under the Controlled Substances Act of 1970.

Industrial hemp is not the pot plant cultivated by people hoping to grow their own weed. Under the Farm Bill of 2018, industrial hemp is no longer listed as a controlled substance so long as it contains no more than 0.3 percent THC.

One byproduct of that change in the law is the booming market for another hemp-derived molecular compound, cannabidiol, or CBD. That’s typically marketed for its purported health benefits. You can get a dose of it in your coffee if you go to the right cafe.

The claimed health benefits of CBD for the most part lack the imprimatur of the Food and Drug Administration. The FDA has approved only a few products derived from hemp, and has sent warning letters to some companies making scientifically hazy claims about CBD products.

As all this gets sorted out by scientists and regulators, the hemp industry continues to expand. It’s still a tiny slice of the agricultural commodities market, but that could change. Hemp could be an excellent source of animal feed if government regulators approve it, said Erica Stark, executive director of the National Hemp Association. The seeds of hemp do not contain any THC, she said, and are high in protein.

“It’s going to be such a really large market. There’s actually animal feed shortages in this country right now, ramifications of what’s happening in Ukraine, droughts and other crop failures,” Stark said.

The researchers at the German Federal Institute for Risk Assessment found no behavioral change in cows given the entire hemp plant, which contained very low levels of THC. Only when fed the portions of the hemp plant with higher THC concentrations – including the flowers and leaves – did the behavioral effects appear, according to the study.

Those effects included slower heart rate and respiration, “pronounced tongue play, increased yawning, salivation, nasal secretion formation,” and reddening of a portion of the eyes, the report states.