Stoned in the barn: When cows eat large amounts of industrial hemp, they are not only visibly intoxicated – the intoxicating substances of the plant are also found in the milk. Values measured in tests by the Federal Institute for Risk Assessment were in some cases above those considered harmless. So can you get high from drinking this milk?
When feeding cows industrial hemp, under certain circumstances, intoxicating substances can be transferred to the milk. This is shown by experiments in which the animals – unlike in agricultural practice – ate larger amounts of these plants.
In the experiments, some of the values measured in the milk were above those that are considered harmless for human consumption, reports scientists from the Federal Institute for Risk Assessment (BFR) in Berlin in the specialist magazine “Nature Food”. Despite these results, it is not to be expected that consumers in Germany will get high from drinking milk. According to the German Farmers’ Association (DBV), only feed from the seeds of the plant that does not contain any intoxicating ingredients is currently permitted.
In the case of the cows participating in the experiments, however, the hemp feed had a visibly foggy effect: they seemed tired, yawned frequently and sometimes swayed. They also ate less and gave less milk.
Industrial hemp, also known as industrial hemp, contains less psychoactive tetrahydrocannabinol (THC) than hemp grown for intoxicants or medicinal purposes. Farmers in the EU are allowed to grow industrial hemp if it does not exceed a specified THC level. 0.2 percent is allowed at the moment. The intoxicating effect is mainly due to the so-called delta9-THC. In addition, numerous other substances from the group of cannabinoids can be found in hemp.
Experts are discussing whether not only the seed but also other plant components or the whole plant are suitable as animal feed. With their study, the researchers led by Bettina Wagner are now examining the extent to which this could be associated with health risks for consumers. So far there have only been a few studies on the question of whether the intoxicating ingredients are transferred to the milk.
In their experiments, the researchers first replaced part of the feed of Holstein-Friesian cows with hemp silage, i.e. hemp feed preserved by fermentation. The hemp silage in this habituation phase was obtained from the entire hemp plant and had only a small proportion of cannabinoids.
In the subsequent phase, they gave the dairy cattle silage made from the leaves, flowers and seeds of the hemp plant, which had higher levels of cannabinoids. Two groups received different amounts of this feed – 0.84 kilograms and 1.68 kilograms per cow and day. The animals therefore consumed different amounts of cannabinoids. The researchers analyzed the animals’ blood plasma, feces and milk for cannabinoids, measured heart rate and respiration and observed their behavior.
The results: The initially administered hemp silage with a low cannabinoid content did not affect the cows or their health. With higher cannabinoid levels, however, the effects on the animals were clearly visible and measurable: they yawned more, salivated and the formation of nasal secretions increased, their eyes reddened. Some animals from the high-dose group walked unsteadily, sometimes staggered or remained in an unusual posture for an unusually long time. Heart and breathing rates dropped significantly, and from the second day feed intake and milk production also decreased significantly. Within two days of stopping the cannabis feed, all abnormalities disappeared.
In humans, the lowest delta9-THC value that can cause impairment is 0.036 milligrams per kilogram of body weight, the scientists write. On average, the cows ingested up to 86 times more THC with their feed, which presumably explains the health effects.
As further research showed, delta9-THC and some other cannabinoids were also found in milk. At the end of the feeding phase, the values measured were significantly higher than those measured in the blood plasma, which could indicate accumulation. Some cannabinoids were still detectable in the milk after the 8-day weaning period. What does that mean for a possible consumption of such milk? To find out, the researchers used software to calculate how much THC a person would absorb from milk and milk products based on the measured values.
In fact, the level measured in animals that ate the highest amounts of hemp exceeded the delta9-THC reference level, which is considered safe for humans, by up to 120 times. Even milk obtained during the adaptation phase of the experiment would not be safe for toddlers with an above-average consumption of milk and dairy products – the delta9-THC value exceeded the limit value by a factor of 1.5.
“Our study shows that feeding industrial hemp silage to dairy cows, even in small amounts, is associated with health consequences,” the researchers conclude. These appeared to depend on the cannabinoid concentration of the silage, which was influenced by the variety, the parts of the plant from which the silage was obtained and the time of harvest, among other things. “Due to the variety of parameters that influence the cannabinoid concentration of hemp and feed derived from it, the safety of hemp cannot be reliably assessed without prior cannabinoid analysis.”
According to the farmers’ association, industrial hemp is currently being cultivated on almost 7,000 hectares in Germany, and the trend is increasing. “In addition, there are around 5 million hectares of grassland, which form the basic fodder for ruminants,” according to the farmers’ association. The cultivation is associated with a lot of effort, especially bureaucratic. “Cultivation and flowering must be reported to the Federal Office for Agriculture and Food, and there are also on-site controls for the permitted THC content.” Harvesting is also difficult because there are currently hardly any devices that can handle the stubborn fiber. Overall, from the point of view of the DBV, it is rather unlikely that ruminants will increasingly be fed industrial hemp.
The fibers of the plant are primarily used industrially, for example to produce textiles or insulating materials. The THC-free seeds are used as food or used to obtain hemp oil, which is also used in food and in the cosmetics industry.