Evaluation of hemp hulls and screenings as alternative feed ingredients for ruminants

This study evaluated the effects of hemp by-products on in situ degradability, cannabinoid residues in the milk of lactating ewes, and growth performance and tissue cannabinoid residues of lambs. Experiment 1 assessed the in situ degradability of wheat screenings (control), hemp hulls and screenings. The ruminal degradability was greater (P < 0.01) for wheat screenings compared to hemp by-products. In experiment 2, fifteen lactating Canadian Arcott × Suffolk ewes were assigned to either 15% wheat screenings, 15% hemp hulls, or 15% hemp screenings (dry matter (DM) basis). No cannabinoid residues were detected in milk 4 h post-feeding from ewes. In experiment 3, twelve Canadian Arcott × Suffolk ram lambs received the same three treatments as the ewes, except wheat or hemp ingredients were included at 20% DM. Hemp hulls increased (P = 0.03) DMI compared to wheat screenings, but weight gain was unaffected (P ˃ 0.05). Cannabinoids were detected in muscle, fat, kidney, and liver of lambs fed hemp by-products. Our findings support the utilization of hemp by-products in ruminant diets; however, a withdrawal feeding period may be required when inclusion levels exceed 10% DM in lamb diets to prevent detectable cannabinoids at slaughter.