Feasibility of producing Comfrey (Symphytum spp.) pellet as a feed supplement

Abstract

Comfrey (Symphytum spp.) is highly valued animal feed supplement which commands premium price in some parts of the world. It is a well documented medicinal plant which is easy to grow, but due to low fiber content, and high moisture and protein contents, is not as easy to dehydrate. The objective of this study was to generate preliminary information on cultivation and chemical composition, with emphasis on toxic pyrrolizidine alkaloids (P As), of two comfrey species: S. officainale (common) and S. uplandicum (Russian). Also, the feasibility of pilot scale dehydration and pelletization of leaves was to be established. It was found that in comparison to alfalfa pellets, comfrey pellets were less durable (73% vs. 89%) and less hard (4.3 MPa vs. 6.84 MPa), but in appearance and some physical properties they met the alfalfa industry standards.