The plant Cannabis sativa L. is classified primarily by its chemical composition. Industrial hemp is a variety cultivated for its seeds, fiber, and extracts, and must contain less than 0.3% delta-9 tetrahydrocannabinol (THC) by dry weight to be legally distinguished from marijuana. This globally grown agricultural crop is consumed by animals as a destructive pest target, a controlled livestock feed ingredient, and an occasional graze for wildlife.
Primary Pests that Damage Hemp Crops
A diverse group of small animals and insects interact with the hemp plant, often causing damage rather than consuming it as a food source. Insects with piercing-sucking mouthparts, such as aphids, thrips, and whiteflies, extract plant sap, leading to wilting and nutrient stress. Spider mites are particularly destructive, feeding on chlorophyll and causing stippling damage before spinning dense webbing.
Root-level pests include beetle grubs and wireworms, which bore into the roots and lower stalks, compromising structural integrity and nutrient uptake. Among the most serious threats are lepidopterous stem borers, such as the European corn borer, which tunnel through the stem tissue. Field rodents, including gophers, also act as pests by gnawing on roots, while slugs and birds damage seeds and young plants.
Hemp Byproducts in Livestock and Poultry Feed
The most significant consumption of hemp occurs within agricultural systems, where its byproducts are studied as sustainable feed ingredients. Hemp seed derivatives, like hemp seed meal or cake (the residue after oil extraction), are rich in protein, containing approximately 20% to 25% crude protein and essential amino acids. The seeds also contain 25% to 35% oil, valued for its high content of polyunsaturated fatty acids and a desirable omega-6 to omega-3 ratio.
These nutritional components make hemp byproducts a viable alternative to conventional protein sources. Studies involving ruminants, such as cattle and sheep, indicate that incorporating hemp seed meal can improve the fatty acid composition of milk and meat products. For poultry, hemp seed oil and meal enhance the nutritional profile of eggs and meat by increasing beneficial omega-3 fatty acids. Research on swine and aquaculture species suggests that hemp-derived ingredients support growth rates and feed efficiency. The nutritional rationale centers on utilizing hemp’s natural composition to achieve health and production benefits across diverse livestock.
Consumption by Wild Herbivores and Grazers
Wild herbivores and grazers occasionally consume raw hemp plants in the field. Animals like deer, elk, and rabbits have been observed interacting with hemp crops, sometimes drawn to the readily available biomass. The palatability can be inconsistent, as the plant’s strong, pungent scent may cause deer to bypass it.
However, if other food sources become scarce, these larger mammals will readily graze on the leaves and stalks, potentially causing significant localized damage to field margins. Goats are known to be non-selective eaters and often consume the plant when given the opportunity.
Safety and Regulatory Status of Animal Consumption
A major concern with feeding hemp to any animal is the transfer and accumulation of cannabinoids, particularly THC, into the food supply. Regulatory bodies are concerned that even the low THC levels in industrial hemp could concentrate in animal products such as meat, milk, and eggs. For instance, the transfer rate of orally consumed THC into the milk of dairy cows has been estimated at approximately 0.15%.
Current federal and state regulations in the United States, through the Food and Drug Administration (FDA) and the Association of American Feed Control Officials (AAFCO), have not broadly approved hemp products for animal feed. The use of whole hemp plant material is often restricted, with some limited approvals for specific seed-derived ingredients, such as hemp seed meal, for certain species like laying hens.
Regulatory bodies often impose strict limits on residual cannabinoid levels, such as the FDA-CVM’s endorsement of a cap of 2 parts-per-million for total THC in approved hemp feed ingredients. These restrictions also apply to companion animals, where products containing cannabidiol (CBD) are often classified as unapproved drugs. Until more data exists on cannabinoid metabolism across all species, caution remains the default approach for most regulatory agencies.