Evaluating Methods of Estimating Forage Intake by Grazing Cattle

Two methods of estimating forage intake of grazing cattle were compared to clipped estimates in 4-pasture rotational grazing systems on Sandhills subirrigated meadow from mid-May through early August over a 4-year period. Clipping standing vegetation samples within a pasture before and after cattle grazing provides for an accurate estimate of forage removal during a grazing period. A less laborious method of intake estimation commonly used is based on a percentage of an animal’s liveweight. University Extension and some federal agencies use a 2.3% factor and others such as the Natural Resources Conservation Service use a 2.7% factor. In this study on a Sandhills subirrigated meadow, the 2.3% of body weight intake factor appropriately matched the clipping estimates in 63% of the evaluations. In contrast, the 2.7% of body weight factor provided similar estimates to the clipping estimate in only 38% of the evaluations. This implies that the 2.3% estimate more accurately represents forage intake of beef cattle and has less chance of overestimating cattle intake. Allocation of surplus forage to grazing cattle reduces harvest efficiency, reduces beef production per acre, and negatively effects profitability of beef operations