A REVIEW OF LIVESTOCK GRAZING AND WHEAT-GRAIN YIELD - BOOM OR BUST

Winter wheat (Triticum aestivum L.) grown as a dual-purpose crop is a unique and economically important resource, especially in the southern Great Plains. Since the last major review of grazing effects on grain yield, in 1956, wheat cultivars have been developed that may affect t he productivity of the grazing-grain enterprise. Thus, we decided to r eview current research on grazing winter wheat and the effects on grai n yield in light of earlier information. During a gear of favorable pr ecipitation and adequate to excess soil fertility, tall winter wheat c ultivars grazed prior to jointing experienced increased grain yield re lative to nongrazed wheat, because of reduced lodging. Current researc h suggests that the grain yield of semidwarf wheat cultivars is more s ensitive to forage removal than for tall cultivars. Grazing terminatio n dates necessary to prevent grain yield reduction of semidwarf cultiv ars also appear to be much earlier than for taller wheat cultivars. Th e reason for the difference in grazing tolerance is not clear; however , research suggests that semidwarf cultivars require maximum leaf area at anthesis for maximum grain yield. Tall wheat cultivars are not aff ected in the same manner, and decreased leaf area due to later grazing does not reduce grain yield of taller wheat cultivars to the same ext ent as for the semidwarf cultivars. Thus, taller wheat cultivars have the potential for extending the grazing period for livestock producers while producing grain yield similar to that of semidwarf wheat cultiv ars (which generally produce more grain in a nongrazed situation).