ABSTRACT
Summary Recent development of hybrid forage grasses shows promise for advancing grassland agriculture. Previous selections within these hybrids have been based on morphological, reproductive, and adaptive attributes with only limited testing of animal acceptability. Testing of animal preference and selectivity was the primary purpose of the present study. Yearling cattle were tamed and observed for their selectivity in grazing individual plants and genetic lines of F6 crosses between quackgrass (Agropyron repens) x bluebunch wheatgrass (Agropyron spicatum). Animals showed definite preference for individual plants within genetic lines and for different genetic lines. Different animals frequently preferred the same plant or lines with identical genetic backgrounds. Preferences were exhibited even though animals were provided access at different times or different locations to a large array of hybrid plants or given a choice between hybrids and other palatable forage species. Selectivity was not necessarily associated with observed agronomic or morphological traits. Animals preferred plants rated as caespitose to those ranked rhizomatous. They also selected plants that had a profusion of soft leaves as well as plants with stiff, erect leaves. The most significant feature was the consistency in selection for certain plants and genetic lines. Hybrid forages can be developed solely on the basis of plant-breeding criteria and human judgment, but this kind of development may result in plants with reduced utility for forage except under forced utilization. Conversely, developing hybrids entirely on the basis of animal preference may also limit utility. Plant breeding and forage use by animals need to be concurrently evaluated to assure the predetermined objective of plant improvement.
