The susceptibility of hay species to mechanical damage. II. Effects of moisture content and variety

Abstract

Separate effects of leaf and petiole or stem moisture contents on the susceptibility of hay species to mechanical damage during field curing and storage have been investigated. Three legume species were considered: lucerne (Medicago sativa L.), white clover (Trifolium repens L.), and subterranean clover (T. subterraneum L.). Several types of damage contributed to mechanical loss. The most important over the hay moisture content ranges normally encountered during field curing and storage were the breaking up of individual leaflets, fracture at leaflet–petiole junctions, fracture of petioles, and, with lucerne, fracture of side branch stems. Leaf, petiole, and stem moistures: either separately or jointly, affected the amount of each type. Most serious losses were from the leaf portion, but under some conditions up to 25% of the shattered material petiole and stem. The amount of leaf loss was determined largely by the leaf moisture content, but under some conditions more than half the leaf loss resulted from petiole or stem fracture, which was virtually independent of leaf moisture content. Individual plants within varieties and varieties within species differed in susceptibility to the various types of damage. Differences appeared to be inherent properties of the plants or varieties, and may be considered as potentially available for incorporation into standard varieties of hay species by selection or breeding. Overall reductions in susceptibility thus available were large, e.g. at least 46% with lucerne.