A new study shows that cows can safely consume the plant waste left over from CBD extraction without THC showing up in milk or edible tissue, provided the animals are weaned off the feed for at least two weeks before milking or processing.
The findings are significant for U.S. CBD hemp farmers, who generate large volumes of low-value biomass. Researchers say the results pave the way toward FDA approval for using the material as livestock feed and could unlock new markets for struggling producers.
The peer-reviewed study, conducted by Oregon State University and published in the Journal of Agricultural and Food Chemistry, followed 18 dairy cows fed a diet that substituted alfalfa pellets with 13% spent hemp biomass over 28 days. After a subsequent four-week withdrawal period, all milk and tissue samples tested below detectable levels for THC and other cannabinoids.
‘One step forward’
“Two weeks of spent hemp biomass withdrawal from the diet of the cows eliminates any risk of ingesting THC by consuming the milk from those cows,” said lead researcher Massimo Bionaz. “This study is one step forward in providing the data needed for FDA approval of spent hemp biomass as a feed supplement for livestock.”
The work builds on earlier findings that spent biomass, hemp seed, and hempseed meal are all viable and safe as feed ingredients for livestock. The limited approval of hempseed meal and new findings on spent CBD biomass reinforce the industry’s push to integrate hemp into full-plant utilization models, creating new revenue streams and reducing waste.
Gaining ground
While spent biomass remains under FDA review, other hemp-based feed ingredients are advancing through regulatory channels. Hemp growers and advocates have long promoted the nutritional value of hemp seed, seed cake, and oil for livestock and pets, citing high levels of protein, fiber, and essential fatty acids.
In 2024, the Association of American Feed Control Officials (AAFCO) approved a final definition for hempseed meal — also known as seed cake — for use in laying-hen rations, overcoming opposition from European and Canadian trade groups over THC and CBD limits. The move allows U.S. states to begin commercial adoption of hempseed meal as an approved feed component.
Path forward
Despite growing scientific support, hemp-derived feed materials face ongoing regulatory barriers in the U.S., where the FDA and AAFCO have been slow to approve many cannabis-related inputs for commercial livestock. Proponents argue that the delay is out of step with sustainable agriculture trends and ignores mounting evidence of hemp’s safety in animal diets.
Limited state-level approvals and pilot programs have already demonstrated positive results in poultry, cattle, and aquaculture settings. Advocates say that feed applications represent one of the most promising market extensions for hemp, particularly in light of oversupply and stagnation in the CBD sector. With safety studies now filling critical data gaps, industry groups are renewing their calls for swift federal action.