Sources of variation in the foraging efficiency of grazing ruminants

1. The relationships between foraging behaviour, incisor arcade breadth and body mass were described for sheep and goats grazing from swards of sown grass at two sward surface heights. 2. variation in bite mass was related to incisor arcade breadth more closely than to body mass. 3. Bite area scaled as the square of the incisor arcade breadth and was smaller on the Tall sward height treatment. 4. Sheep had greater bite masses than did goats but goats had a higher bite rate than sheep and as a consequence there was little difference in short-term intake rate between the species. 5. Young animals of both species had smaller bite masses and intake rates than did mature animals. However, when expressed relative to body mass there were no significant differences in bite mass between maturity classes. 6. The results of the current study confirm that the size of the incisor arcade is a direct determinant of bite dimensions and a driving variable for intake rate in grazing ruminants.