Photos courtesy of Oregon State University
In 2020, OSU researchers studied hemp in lamb diets.

Shortly after the passage of the Agricultural Act of 2014 (the 2014 Farm Bill), Oregon was one of the first states to license hemp production, as the state’s department of agriculture (ODA) began accepting applications for industrial hemp licenses in 2015. Since then, the majority of Oregon farmers have grown hemp for cannabidiol (CBD) production, says Dr. Massimo Bionaz, Ph.D., re-searcher and associate professor in the Department of Animal and Rangeland Sciences at Oregon State University (OSU). However, CBD production creates high quantities of spent hemp biomass—made up of the plant’s extracted leaf and stalk portions.

Dr. Serkan Ates, Ph.D., researcher and assistant professor in OSU’s Department of Animal and Rangeland Sciences, says farmers have struggled to find an end use for these leftover hemp byproducts.

Bionaz, Ates and other researchers are working together on several studies to address this agricultural challenge.

The researchers received $299,950 in grant funding from the U.S. Department of Agriculture (USDA) National Institute of Food and Agriculture (NIFA) in February to study feeding spent hemp biomass to cattle. The grant aims “to implement the safe use of hemp byproducts in livestock diets and take full advantage of their nutritional and potential medicinal properties to improve animal health and the quality of animal products.”

OSU’s primary objectives with the study are to collect enough data to encourage the U.S. Food and Drug Administration (FDA) to legalize the use of hemp byproducts in livestock diets and create an extension program to connect producers with the hemp industry, the grant states.

Hemp byproducts are currently not approved by the FDA to be used in livestock diets, Bionaz says.

Yet, the amount of hemp byproducts being produced both nationwide and in Oregon has experienced exponential growth. In 2015, the ODA reported 13 licensed hemp growers and 13 processors. Just four years later, in 2019, those numbers skyrocketed to 1,961 growers and 597 processors licensed.

In 2020, Oregon licensed 1,678 growers, 515 processors and 26,377 acres for hemp cultivation. Based on 2020 data compiled by Hemp Grower, Oregon had the fifth-highest number of acres licensed for hemp out of all 50 states.

OSU’s cattle study is just one of three hemp-related experiments the university’s researchers have taken or will take part in. Last year, OSU scientists ran a similar experiment on lambs. They are also preparing to conduct a study on poultry sometime this fall, pending approval by the Institutional Animal Care and Use Committee (IACUC), Bionaz says.

The Lamb Experiment 

The lamb experiment ran from July 1 to Oct. 1, 2020, and consisted of three stages: the adaptation period (three weeks), period one (four weeks) and period two (four weeks). The trial consisted of five lamb groups: a control group, Low Hemp 1 (LH1), Low Hemp 2 (LH2), High Hemp 1 (HH1) and High Hemp 2 (HH2).

The control group was fed grains (maize, barley and soybean meal), orchardgrass hay (10%) and alfalfa. In both the experimental and control diets, grains and orchardgrass were the common ingredients, but in the experimental diet, the researchers replaced alfalfa with spent hemp biomass.

During the adaptation period, researchers fed lambs in the experimental-diet groups a small amount of alfalfa and hemp for three weeks to get them accustomed to the hemp.

In period one, the researchers fed each group a mix with different ratios of hemp and alfalfa. In period two, scientists switched two of the groups to a regular diet of grains, alfalfa and orchardgrass hay.

“The two groups that went back to the controlled diet after the first four weeks of the experiment were the withdrawal groups,” Ates explains. “That was done just to see the effects the withdrawal had on the [lamb] meat.”

The researchers designed the experiment to analyze the presence of tetrahydrocannabinol (THC) and CBD residuals in meat of lambs fed spent hemp biomass and determine the effects the cannabinoids had on the lambs’ health and performance. The researchers also analyzed the lamb’s “typical carcass quality parameters and quality of the meat,” including the meat’s fatty acid composition. The researchers then compared the low and high hemp groups and looked at the animals’ feed intake and liveweight gains, Ates says.

“The groups that had the high spent hemp biomass diet [the 20% groups] had statistically less feed intake during the first period compared to all the other groups, and the low hemp groups [the 10% groups] had a similar feed intake as the control groups,” he says. “When we removed the hemp from two of those groups’ diets in the second period, it was really interesting to see that in that second period, their [feed] intake was statistically higher. Higher feed intake was also observed for the group that received 10% spent hemp biomass during the second period, but we are still trying to understand the reason for that.”

The researchers originally hypothesized that the spent hemp biomass would have a detrimental effect on the lamb’s performance, but Bionaz says it appears to have had no effect; however, they have not reached a conclusion on that yet.

“This is all preliminary data,” Bionaz says. “We cannot make a final conclusion on any of this data, but these are some of the very interesting findings that we are trying to investigate more. The final findings cannot be concluded until the data has gone through a final review process and is accepted for publication in a peer-review journal. When that happens, then the data will become publicly available.”

A control ration and hemp rations that Oregon State University researchers fed to lambs.

The Cattle Experiment

The cattle study began May 3 and is expected to run through the summer, Bionaz says.

Similar to the lamb trial, the cattle study consists of five groups and is broken down into three stages: the adaptation, intervention and carry-over stages.

There is no specific hemp variety used for the experiment, as it is likely the varieties get mixed in the processing centers the researchers source the hemp from, Bionaz says.

The quality of the feed is comparable to alfalfa, with some parameters, such as fat and minerals, being higher, Bionaz says. The biomass contains about 19% to 21% crude protein (compared with anywhere from 12% to 20% for alfalfa, according to University of Nevada, Reno), along with 3% to 7% fat, 23% to 44% of fiber and a high mineral content, he adds.

Once they complete the study, the researchers will analyze the effects the spent hemp biomass had on the cattle’s health, metabolism, liver and milk quality and composition. They will also determine the residuals of cannabinoids left in various areas of the cattle.

“While the objective is to check the amount of cannabinoids in the milk, we will also be looking at the accumulation of cannabinoids in meat by taking muscle biopsy in the adipose tissue, which we will take at the end of the first four weeks of feeding, and then following those four weeks of feeding hemp, we will have four weeks of withdrawal,” Bionaz says. “Then, two weeks into the withdrawal, we will conduct another biopsy to see if the cannabinoids have been removed from the body.”

Ates says it’s essential to conduct a trial study on three different animal species (poultry, lambs and cattle) for a couple of reasons: they all have different metabolisms; they will process the spent hemp biomass and its components differently; and their production types are different, so the end products for the hemp spent biomass might vary in milk compared to meat, Ates says.

One of the biggest hurdles with this research study is the expense, Bionaz says, because the meat from the cattle used in the study cannot be sold to the market due to regulations from the FDA, which has not yet approved hemp for any animal consumption. So, any meat from animals previously fed hemp would be considered “adulterated” by the USDA.

But the grant from NIFA will help provide the researchers with enough funds to do a “true investigation” on spent hemp biomass with cattle, Bionaz says. And the researchers also submitted a request to the FDA asking the agency to let the animals to go back into production after some time following the study, Bionaz says.

Looking Ahead

Utilizing spent hemp biomass as a source of livestock feed can benefit both the hemp and livestock industries, Ates says.

Using spent hemp biomass can help producers reduce their waste and create other environmental benefits, Ates says. “And from the livestock producers’ perspective, the spent hemp biomass might be a very good quality and cheap alternative feed for them, which can help them reduce their feed cost,” he adds.

Additionally, it could help create a more circular system between crops and livestock on the farm, he says.

“In the meantime, we will be collecting data from the animals, processing those samples and analyzing them in our labs,” Bionaz says.

By the end of 2021, the researchers plan to publish a peer-reviewed article with the finalized data conclusions from the lamb study to understand better the experiments and what’s working, he says. 

Furthermore, the research team is continuing to design and develop additional studies depending on the availability of the grants and other resources. As Ates says: “The sky’s the limit for hemp.”

Andriana Ruscitto is assistant editor for Hemp Grower, Cannabis Business Times and Cannabis Dispensary.