Plasma cannabinoid concentrations and transference during long-term industrial hemp administration in cattle

With recent legalization of industrial hemp (IH) production and increased interest in including IH and its byproducts in cattle feed, there is a need to establish the pharmacokinetic profiles of cannabinoids in cattle and guidelines for animal surveillance programs to ensure safety of cattle products entering the food supply. Our group has previously described the pharmacokinetics of cannabidiolic acid (CBDA) and concentrations of other cannabinoids in plasma. In the present study, the plasma cannabinoid concentrations in twelve (12) Holstein steers receiving alfalfa pellet placebo (PLBO), chlortetracycline (CTC) pellets (1.1 mg/kg/d), IH (5.5 mg/kg/d CBDA; HEMP), or a combination of CTC and IH (COMBO) once daily for 63 d were evaluated. Plasma samples were collected every 7 d from day -7 to 77. Eleven cannabinoids were detected above the lower limit of quantification (LLOQ), with the cannabinoid (-)-7-nor-7-carboxy cannabidiol (CBD-7-acid) reaching the highest concentrations. All cannabinoids except CBD-7-acid were below LLOQ by 14 d after final hemp administration. In cattle not receiving IH, CBD-7-acid was detected in multiple steers and timepoints. CBDA was detected in 4 samples (2 steers from each of the PLBO and CTC groups). Both 9-THC and its precursor, THCA, were detected above LLOQ in a singular sample from a steer in the CTC group. These findings suggest that cattle not receiving IH could have detectable concentrations of CBD-7-acid in the blood if cohoused with animals that are exposed to IH. Sample contamination may have been responsible for the detectable 9-THC, THCA, and CBDA concentrations. Based on our results, CBD-7-acid may be a useful tool for screening cattle for IH exposure. However, given the consistent, detectable concentrations in groups not administered IH, a confirmatory test or specific criteria for interpreting CBD-7-acid concentrations would be warranted. These data will help inform decisions regarding surveillance and tolerances for cannabinoid testing in food animals and animal products entering the food supply.