Updated: Apr 30
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A November 2022 peer-reviewed research study conducted in Germany entitled "Transfer of Cannabinoids into the Milk of Dairy Cows Fed with Industrial Hemp Could Lead to Δ9-THC Exposure that Exceeds Acute Reference Dose" that was published in the journal Nature Food investigated the potential effect of dairy cows fed hemp feed.
Do holsteins fed hemp get high?
The study explained that the expanding global hemp industry has "launched many novel hemp-derived products, including animal feed" and that the need exists to understand "to what extent individual cannabinoids from industrial hemp transfer from the feed into products of animal origin and whether they pose a risk for the consumer."
The study noted the need to understand "to what extent individual cannabinoids from industrial hemp transfer from the feed into products of animal origin and whether they pose a risk for the consumer."
The study's authors focused on the issue of the ramifications of hemp proliferation within the human food chain, which it claimed "raises consumer safety issues because hemp contains cannabinoids, a class of substances that interact with the animal and human endocannabinoid system."
They noted that some cannabinoids, including tetrahydrocannabinol (THC), cannabinol (CBN), and tetrahydrocannabivarin (THCV), exert psychoactive effects, while others—including cannabidiol (CBD) and cannabigerol (CBG)—are not psychoactive, but are "pharmacologically active."
2022 Hemp for Holsteins Study
The researchers observed that "a transfer of cannabinoids into foods of animal origin is conceivable when by-products of hemp production and the whole plant are used as feedstuff."
The study focused on "the effects of industrial hemp silage feeding in lactating dairy cows" with the research goal of "quantifying the transfer of cannabinoids into milk and determining possible effects on animal health and [outcomes] for consumer health."
"The study collected and analyzed milk, blood plasma, and feces from 10 lactating Holstein Friesian dairy cows and also measured physiological characteristics and behavior."
It collected and analyzed milk, blood plasma, and feces from 10 lactating Holstein Friesian dairy cows and also measured physiological characteristics and behavior. Chemical analysis was performed using liquid chromatography-tandem mass spectrometry, with a focus on differentiating between tetrahydrocannabinolic acid (THCA), which is not psychoactive, and THC, which infamously is. THCA is the acidic precursor that morphs into THC under the right environmental conditions, including heat and UV light.
The study analyzed the participant cows and their milk for the following cannabinoids. Those denoted with * are psychoactive.
The scope of the scientific investigation's analysis also included two THC metabolites: 11-hydroxy-Δ9-THC (11-OH-THC), which results when humans ingest (eat) delta-9 THC and it is processed by the liver, and 11-nor-9-carboxy-Δ9-THC (THC-COOH).
2022 Hemp for Holsteins Study Results
The research noted changes in the behavior and appearance of the cows resulting from eating hemp that included "pronounced tongue play, increased yawning, salivation, nasal secretion formation, prolapse and reddening of the nictitating membrane, and somnolent appearance."
The study reported that some of the cows "displayed careful, occasionally unsteady gait," including "unusually long standing and abnormal posture."
The study reported that some of the cows "displayed careful, occasionally unsteady gait," including "unusually long standing and abnormal posture." However, it noted that all changes in behavior or appearance resulting from hemp consumption "disappeared within two days of discontinuing cannabinoid feeding."
It also reported that various constituents of the milk produced by the cows, including fat, protein, lactose, dry matter, somatic cell count, and urea, were unaffected by the hemp consumption. In addition, body temperature and weight remained unaffected by hemp ingestion. The study also observed that "administration of ∆9-THC (but not CBD) influenced respiratory and heart rate and caused drowsiness, slow movements, ataxia, and salivation."
The study revealed that only "a small fraction" of the cannabinoids CBD and THC show up in milk, with 77 percent of THC and 64 percent of CBD "being 'eliminated' in processes such as putative metabolism, biochemical transformations in the gastrointestinal tract, and urinary excretion."
The study found that the transfer rate, or how much of a particular cannabinoid consumed by the cow was carried over into the milk it produces, was greatest for THCV, but that "the low concentrations found in hemp silages make it unlikely to pose a risk to [human] consumers" of the cow's milk.
The study found that the transfer rate, or how much of a particular cannabinoid consumed by the cow was carried over into the milk it produces, was greatest for THCV, a psychoactive cannabinoid.
The research found the transfer rate of CBD and delta-9 THC to be roughly the same. However, because the hemp feed consumed by the cows contained significantly more CBD than THC, milk produced by the cows featured CBD levels that were "markedly higher" than those of THC. "Thus, CBD may be as relevant as Δ9-THC when assessing consumer [outcomes]," concluded the study's authors.
The lowest milk transfer rates were observed for the cannabinoids CBN and CBDV, "confirming that Δ9-THC and CBD are the main compounds of interest for animal health and consumer safety."
The study also revealed that study participants fed a particular hemp feed mix that is rich in cannabinoids, a "silage made from leaves, flowers and seeds" resulted in a decrease in feed intake and milk yield. However, a different hemp feed mix, a "low-cannabinoid industrial hemp silage made from the whole hemp plant" displayed "no effects on cow health and performance."
Terpenes & Flavonoids
The study noted that it is difficult to cite direct causality between particular cannabinoids and the responses of the cows due to "combination effects" and the fact that hemp produces many types of molecules other than cannabinoids, including terpenes and flavonoids.
2022 Hemp for Holsteins Study Conclusions
One shortcoming of this study was the extremely small sample size of only 10 participants. While the data reported by this research is of considerable scientific value, additional studies involving significantly larger sample cohorts (groups) must be conducted to validate the findings published by this German study.
"One shortcoming of this study was the extremely small sample size of only 10 participants."
The scientific modelling employed by this research revealed that the transfer rates of the examined cannabinoids from feed to milk "were less than one percent." However, it noted that the cow's milk "reached substantial levels of Δ9-THC such that the exposure might exceed [reference standard] ARfD in some population groups," but that data for CBD are "currently insufficient, thereby preventing an assessment of possible health [outcomes]."
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