Antimicrobial properties of secondary metabolites of Cannabis sativa: A promising natural alternative for livestock health

Inaddition totheir practical importance asamedicinal plant, animal feed and asource ofmaterials for the textile and construction industry, industrial varieties ofCannabis sativaL. (hemp inawider sense) provide analternative for controlling infectious diseases inlivestock. Despite the genetic divergence between two primary groups ofcannabis, i.e. medicinal cannabis and technical hemp, hemp plants also produce awide spectrum ofsecondary metabolites. These include the main classes ofcannabinoids and terpenoids, aswell asrepresentatives offlavonoids, stilbenoids, steroids, alkaloids, spiroindans, dihydrophenanthrenes, and lignanamides. Many ofthem exhibit antibiotic activity which can substitute orcomplement the use oftraditional antibiotics inanimal husbandry. For example, the cannabinoid fraction exhibits activity against the Gram-positive bacteria and some fungi. While the activity against Gram-negative bacteria isnot characteristic ofcannabinoids, these pathogens can still beaffected byhemp terpenoids and flavonoids. The synergy among the secondary metabolite fractions orbetween the hemp metabolites and traditional antibiotics isalso afavourable factor. The search for alternatives totraditional antibiotics isfurther driven bythe increasing prevalence ofgenetically determined antibiotic resistance among veterinary pathogens, which poses the additional risk oftransferring resistance traits tothe human pathogens. The content ofantibiotically active compounds inhemp can beenhanced through selection among existing genotypes, targeted breeding, cultivation conditions, and even byspecific elicitation ofsecondary metabolites with the natural antibiotic function inthe disease resistance ofthe plant. The switch tohemp metabolites isalso supported bytheir compatibility asnatural components ofplant-based animal feed, and byfavourable economic considerations.