The effect of hemp leaves on intake, digestion, and rumen fermentation parameters in beef steers

Hemp (Cannabis sativa L.) cultivation creates by-products (i.e., seedcake and leaves) that, if not placed in an existing market, may be wasted. This waste could be mitigated by feeding these by-products to livestock. Hempseed meal (HSM) has been approved for poultry feed in the U.S. at ≤20 % dietary inclusion. However, HSM is also used in human markets, reducing its economic viability as livestock feed. Research has indicated that hemp leaves have similar nutritive value to conventional forages and may be a suitable feed for ruminants; however, in vivo digestibility studies are lacking. The objective of this study was to evaluate the effect of hemp leaf supplementation at a dose of 3.9 mg/kg body weight (BW) cannabidiolic acid (CBDA) on intake, digestion, and rumen fermentation in beef steers. Ruminally cannulated beef steers (n = 5) were fed hay and alfalfa cubes for 15-d then fed the same diet supplemented with hemp leaves at 3.9 mg/kg BW CBDA per day for 14-d. Hemp supplementation significantly increased forage intake and total tract digestion of organic matter and neutral detergent fiber (P ≤ 0.01). There were no effects of treatment on ruminal ammonia, total volatile fatty acid concentrations, or ruminal pH (P ≥ 0.60). Hemp supplementation affected molar proportions of acetate, propionate and butyrate (P ≤ 0.01). These data indicate that hemp leaves can be supplemented to cattle at the dose provided (3.9 mg/kg BW CBDA) without negatively impacting diet utilization or rumen fermentation. Future research should confirm these findings at higher levels of hemp inclusion and/or in total mixed rations.