Forage-based beef finishing systems: A review

The objective of this paper is to review alternative methods of increasing the use of forage in beef finishing systems. Most finishing systems based on an all-forage diet have not been particularly successful. Without grain finishing, the final product can have an inconsistent quality grade and a grassy flavor. The greatest sensory difference between forage-fed and grain-fed steers appears to be the flavor of the fat. Diterpenoids seem to be the off-flavor's source. These are derived from the action of ruminal microorganisms as they break down chlorophyll. Phyt-2-ene has been identified as the most discriminating compound for off-favor It was also found to be the strongest indicator that a steer had been forage-finished. As time on grain lengthened, the levels of - tetradecalactone and -hexadecalactone increased, indicating their correlation with desirable flavor characteristics of grain-finished beef. Other investigators have correlated the off-flavor to C 18:3 unsaturated fatty acids. The two methods that show the most promise and increase the use of forage in beef finishing systems are (i) supplemental feeding of cattle on pastures to reduce length of time required for feedlot finishing and (ii) finishing cattle in a pasture with supplemented energy. Efforts to reduce feedlot time have lessened the total concentrate fed and have been economically successful. When finishing cattle in a pasture with supplemental energy, those studies that limited grain intake the last 60 to 80 d before slaughter had mixed results. However, when proper forage management was used in order to ensure adequate supply of high quality forage, carcasses with acceptable quality were produced. Researchers who provided limited supplementation or energy for at least 112 d and fed free choice grain the last 60 to 80 d before slaughter reported that USDA Choice beef was produced. However, USDA quality grade is not necessarily an adequate means to determine the effectiveness of a pasture-based finishing system. Researchers have to determine when meat flavor changes from ''grass'' to ''grain'' and the possibility of achieving this transfer on pasture with energy supplementation.