THC undetectable after withdrawal period in cows fed hemp byproduct

CORVALLIS, Ore. – A new study examined feeding a hemp byproduct to cows and found that the trace amounts of psychoactive THC in hemp were undetectable in the milk and edible tissue of cows if they were weaned off the byproduct before milking or processing.

The findings are significant because the hemp byproducts, known as spent hemp biomass, currently have little to no economic value for hemp producers. Spent hemp biomass has not been legalized as feed for livestock by the Food and Drug Administration due to the potential presence of THC and its potential impacts on animal health.

“This study is one step forward in providing the data needed for FDA approval of spent hemp biomass as a feed supplement for livestock,” said Massimo Bionaz, lead author of the study and an associate professor in the Department of Animal and Rangeland Sciences at Oregon State University.

The legalization of hemp as an agricultural crop in 2018 in the United States and in other countries around the world at the same time resulted in a significant increase in global cultivation.

In the United States, more than 60% of hemp is grown to extract cannabidiol (CBD), while it is grown primarily for seed or hemp oil in Europe and Canada. The CBD extraction process creates a large amount of plant-matter byproduct, referred to as spent hemp biomass.

Past studies by Bionaz and others have found that spent hemp biomass, hemp seed and hempseed meal are suitable and safe feed ingredients for livestock animals, including cattle, lambs and chickens.

For the new study, which was recently published in the Journal of Agricultural and Food Chemistry, the researchers had two objectives:

• Determine the accumulation, absorption and clearance of cannabinoids, including CBD, in milk and tissues of dairy cows fed spent hemp biomass.
• Assess the risks for people when consuming milk from those cows.

The project involved 18 Jersey cows. For 28 days, nine were fed the experimental diet with 13% spent hemp biomass, and nine received the control diet, with 13% alfalfa pellet instead of the spent hemp biomass. The cows then went through a four-week withdrawal period in which they all received the control diet.

The researchers found that dairy cows absorb significant amounts of cannabinoids after eating spent hemp biomass. However, cannabinoids disappear from the system, including the milk, within 15 days.

“Two weeks of spent hemp biomass withdrawal from diet of the cows eliminates any risk of ingesting THC by consuming the milk from those cows,” Bionaz said.

Co-authors of the paper are Agung Irawan, Daniel Nosal, Ruth N. Muchiri, Richard van Breemen, Serkan Ates, Jenifer Cruickshank, Juliana Ranches, Charles Estill and Alyssa Thibodeau, all of Oregon State. Oregon State is also home to the Global Hemp Innovation Center.