The herbage Intake of grazing dairy cows can be estimated either directly from measurements made through the animal or alternatively from sward measurements. Of the animal-based techniques, the most widely adopted method used to estimate herbage intake is the faecal output-indigestlbillty ratio technique. More recently, animal energy requirements have been used as a basis to predict herbage Intake. The objective of the present study was to compare the two animal-based techniques for estimating herbage intake.

Two experiments were carried out during 1984 and 1985. In Experiment 1 a total of 42 lactacing British Friesian cows were allocated to three grazing treatments. Herbage Intakes were estimated over three twelve-day periods during the experiment. In Experiment 2, 40 cows were allocated to three grazing treatments and Intakes were again estimated over three twelve-day periods. Two methods were used to estimate the herbage Intake of the cows. Method 1 involved the estimation of herbage intake from animal energy requirements using both observed liveweight changes (Method 1a) and liveweight changes calculated from a regression analysis of llvewelghts over the experitmental period (Method 1b). With Method 2 intakes were estimated by the faecal output-indigestibllity ratio technique.