Stone the cows – and they get drowsy and high, say scientists

COWS appear to get stoned after eating hemp feed and then produce milk that could make people drowsy, a new study suggests.

The recent legalisation of cannabis in many countries, including parts of the United States, has triggered a booming industry in hemp (Cannabis sativa) products and spin-offs, including some animal feeds.

However, there has been little research on whether the animals experience unwelcome physiological effects and whether any of the psychoactive properties of cannabis could be passed on to humans through the food chain.

Germany, which is in the process of decriminalising the cultivation and possession of cannabis, decided to find out.

Researchers at the German federal institute of risk assessment gave cannabinoid-rich industrial hemp silage to 10 dairy cows. They discovered that animals showed significant behavioural changes, including increased yawning, salivation, tongue play and unsteady movements. The cows appeared drowsy and often stood for unnaturally long periods in abnormal postures.

The team also tested their milk and found high levels of THC – the main psychoactive compound in cannabis that produces the “high” sensation.

Levels in the milk were so high that humans who drank it could suffer drowsiness, impaired working memory and mood alterations, researchers said.

“We observed significant changes in respiratory and heart rate as well as a reduction of feed intake and milk yield,” said an institute spokesman, adding that other signs included yawning, salivation, prolapse and reddening of the nictitating membrane, tongue play and nasal secretion.

Consumption of milk with delta-9 THC concentrations, as measured in the current study, could result in intake levels above the acute reference dose, with especially high intakes in children.”

The research was published in the journal