Forage Intake by Grazing Livestock: A Review

A wealth of experimental data has been accumulated on quantitative intake of pen-fed livestock; such information has been widely employed to develop a keener nutritional knowledge of such animals. Data of this type are, however, distressingly lacking for grazing livestock. The procedures used for measuring intake by animals under grazing conditions have often been disappointing, and many have provided unreliable data. Forage intake measurements with grazing livestock are more commonly expressed as g DM or OM/W kg^0.75 or simply as a percent of body weight. Most estimates of intake for cattle and sheep grazing ranges in Western United States fall within the range of 40 to 90 g OM/W kg^0.75 or from 1 to 2.8% of body weight. Intake usually decreases with advancing plant maturity.