Pilot study: Impacts of cannabinoids from industrial hemp and repeated transportation events on cattle health and immune status

Recent legislative approval of industrial hemp (IH) cultivation has increased interest in the possibility of using IH and IH byproducts in livestock feed. Understanding the therapeutic effects of IH is critical for regulatory decisions and application to the cattle industry. The objective of this pilot study was to describe the effects of IH administration on stress and inflammatory biomarkers and activity in cattle experiencing repeated transportation. Twelve Holstein steers (430 kg, SEM = 3.4; 947 lb, SEM = 7.6) were assigned randomly to treatment sequences (n = 3 per sequence) in a 4x4 Latin Square design study (four periods and four treatment sequences). Treatments consisted of one of two drugs (IH or placebo; HEMP, PLBO) and one of two transportation events (transport or control; TRANS, CNTL) during each period so that every steer received all treatment combinations during the study. Industrial hemp was dosed at 5.5 mg/kg cannabidiolic acid (CBDA), with IH or placebo given once by oral bolus immediately prior to the transport or control event. Body weight, accelerometry, kinetic gait analysis, mechanical nociceptive threshold, infrared thermography, complete blood count (CBC), serum biochemistry, blood cortisol, prostaglandin E2 metabolite (PGEM), and serum amyloid A (SAA) were assessed using multiple linear regression. Summary statistics for plasma cannabinoid concentration were generated. There was a drug by transport by time interaction for change in PGEM from baseline (P = 0.03): steers in the HEMP-CNTL group had negative change at 48 h, whereas PLBO-CNTL steers had positive change at 48 h. Both TRANS and CNTL steers had increased lying times in the period immediately after transport. Steers in the TRANS group had greater body weight loss (P <0.0001), neutrophils (P <0.0001), monocytes (P = 0.04), blood glucose (P <0.0001), and total protein (P <0.0001) compared to CNTL steers immediately following transport. Cortisol area under the curve values were greater for TRANS versus CNTL steers (P <0.0001). Lymphocyte concentrations were decreased for TRANS steers compared to CNTL following transport (P <0.0001). There was a transport by time interaction for SAA (P <0.0001), with TRANS steers at 24 and 32 h having the greatest SAA concentrations. Further investigation is required to confirm if feeding IH reduces PGEM. Novel outcomes evaluated in this pilot study will assist in design of future transportation trials.