Review: Utilizing industrial hemp (Cannabis sativa L.) by-products in livestock rations

Authors: ALTMAN, ALEX - University Of Kentucky; KENT-DENNIS, CORAL - Oak Ridge Institute For Science And Education (ORISE); Klotz, James; MCLEOD, K - University Of Kentucky; VANZANT, E - University Of Kentucky; HARMON, D - University Of Kentucky

Submitted to: Animal Feed Science and Technology
Publication Type: Review Article
Publication Acceptance Date: 12/3/2023
Publication Date: 12/9/2023
Citation: Altman, A.W., Kent-Dennis, C., Klotz, J.L., McLeod, K.R., Vanzant, E.S., Harmon, D.L. 2023. Review: Utilizing industrial hemp (Cannabis sativa L.) by-products in livestock rations. Animal Feed Science and Technology. 307. Article 115850. https://doi.org/10.1016/j.anifeedsci.2023.115850.
DOI: https://doi.org/10.1016/j.anifeedsci.2023.115850

Interpretive Summary: The relegalization and reintroduction of industrial hemp (Cannabis sativa) in the United States in 2014 has resulted in the development of a number of different end-products. All of which generate by-products that are currently viewed as waste. This "waste" material has adequate nutritional value, such that it could be considered as an alternative livestock feed. Hemp is also well known for its variety of biologically active compounds that can still be present even in waste plant material. This has limited the usage of hemp by-products in animal agriculture. The purpose of this review is the examine the current state of the literature as it relates to the use of hemp in animal agriculture and identify areas that may be deficient. The lack of knowledge on transference of bioactive compounds from the plant material to animal tissues destined for human consumption was identified as a priority area of research that is necessary to determine the suitability of hemp-derived feeds in food animal agriculture. This review will benefit researchers that are focused the development

Technical Abstract: Since its reintroduction as a legal crop in the United States in 2018, industrial hemp (Cannabis sativa L.) production for cannabidiol (harvested from inflorescence), seed, and fiber has steadily increased. This has led to an increase in the number of hemp-related products, many of which have retail value. However, many of the by-products resulting from further processing of hemp are discarded as waste. A potential use for these hemp by-products may be as a feedstuff for inclusion in livestock diets, thereby providing an additional source of feed in a world demanding increased sustainability. Of the three main components of the hemp plant (e.g., fiber, inflorescence, and seed), hemp seed and inflorescence are the most promising as feeds. Hemp inflorescence in livestock rations is the latest of the three hemp product categories to be investigated, with most published studies relying on in vitro methods. Due to inflorescence being the source of psychoactive cannabinoids, potential contamination of foods entering the human supply chain represents the greatest concern for regulatory bodies. Future research needs to demonstrate that feeding low levels of cannabinoids over prolonged periods does not result in appreciable amounts deposited in animal milk and tissues. Comparatively speaking, hemp seed research has received greater interest than inflorescence or fiber. Hemp seed and its associated by-products have been examined in diets for poultry, sheep, cattle, and swine. Hemp seed cannot produce cannabinoids, which mainly originate from cannabinoid-producing trichomes in the inflorescence. Due to its high protein and fat contents, particularly ruminal undegraded protein and unsaturated fatty acid compositions, this low cannabinoid-containing concentrate may represent the most viable and least controversial livestock feedstuff derived from industrial hemp. However, further research is needed to confirm such a possibility. Comparatively, high fiber products harvested from hemp (i.e., stalk material) have very little nutritional value. Hemp fiber has been largely ignored as a potential feedstuff, as its strength, absorbency, and overall utilitarian properties make it a popular construction and bedding material. Overall, current scientific literature indicates hemp-related products may be suitable for livestock rations, but future investigations are warranted. Primary concerns are still concentrated around defining safe cannabinoid inclusion levels, as these may relate directly to transference rates into animal by-products destined for human consumption. However, secondary concerns such as animal growth performance, health, and behavior must also be considered as future research is formulated.