Effect of Industrial Hemp ( <i>Cannabis sativa</i> ) Supplementation on Rumination Behaviour, Plasma Antioxidant Enzymes and Stress Biomarkers in Angus Cattle

Oxidative stress is known to affect the behaviour, performance and well-being of cattle. The objective of this study was to determine the effect of industrial hemp (IH) supplementation on rumination behaviour, stress biomarkers and antioxidant enzymes in Angus cattle. A total of 20 black Angus heifers were completely randomized into either control (CON) (receiving commercial concentrates) or IH (150 g of IH/kg of commercial concentrates) in a trial that lasted for 35 days with IH supplementation for 21 days and 14 days post-supplementation. Rumination behaviour (rumination time, ruminal pH, temperature and water intake) was recorded with smaXtec bolus, plasma antioxidants (total antioxidant activity [TAA], superoxide dismutase [SOD], glutathione peroxidase [Gpx], catalase [CAT], nitric oxide [NO], malondialdehyde [MDA]) and stress biomarkers (cortisol and heat shock proteins) were analyzed. Results showed that IH supplementation decreased water intake with an average consumption of 51.39 L/day in the IH group and 55.09 L/day in the CON. No significant (p = 0.67) difference was observed in the ruminal pH and rumination time (p = 0.58) of the animals. The TAA increased from 7.26 to 17.95 U/mL in the IH group during supplementation but decreased to 11.48 U/mL post-supplementation. GPx was significantly (p = 0.0023) higher in IH (46.47 mmol/L) than in CON (44.01 mmol/L) group. Similar results were observed with NO. MDA was significantly (p < 0.05) higher in the CON compared to the IH group. Cortisol was significantly (p = 0.03) lower in the IH group (97.54 ng/mL) than CON (122.23 ng/mL). No significant (p < 0.05) difference was observed for heat shock proteins 70 and 72. Conclusively, IH improved rumination behaviour in cattle by maintaining optimum rumen pH. Furthermore, IH increased the antioxidant status as well as the reduction of oxidative stress biomarkers, suggesting that IH supplementation could improve the health and welfare of Angus cattle.