Scientists from the U.S. Department of Agriculture’s Agricultural Research Service (ARS) and North Dakota State University recently found that when cattle were fed with the industrial hemp byproduct, hempseed cake, very low levels of cannabinoids were retained in muscle, liver, kidney and fat tissues, potentially opening up a new market for hemp growers.
While hemp has been used for fiber, food (seeds and oil) and medicinal purposes for thousands of years, hempseed cake, a major byproduct formed during oil extraction from industrial hempseed, cannot legally be used in food animal rations currently because the magnitude of CBD and THC residues remaining in edible animal tissues have not been characterized.
However, hempseed cake is highly nutritious, and the new study shows that it can be a viable alternative feed source for cattle.
In the study, published earlier this year in Food Additives and Contaminants, groups of heifers were fed either a control diet or a diet containing 20% hempseed cake for 111 days. When the feeding period was completed, cannabinoid residues were measured in animals harvested zero, one, four and eight days after hempseed cake was removed from the diet. The hempseed cake used in the study contained an average concentration of 1/3,000 of the legal threshold of 0.3% THC, as defined by the 2018 Farm Bill.
Cannabinoid residues were sporadically detected in urine and plasma of cattle during the feeding period, and low levels (about 10 parts per billion) of CBD and THC combined were measured in adipose tissue (fat) of cattle harvested with no withdrawal period. In liver, kidney and skeletal muscle, however, CBD and THC were below detectable levels in the cattle fed hempseed cake.
“According to our exposure assessment, it would be very difficult for a human to consume enough fat from cattle fed with hempseed cake to exceed regulatory guidelines for dietary THC exposure,” David Smith of Animal Metabolism-Agricultural Chemicals Research Unit in Fargo, North Dakota, said in a press release.
— Brian Beckley