Ingestive behaviour of yearling Friesian heifers continuously stocked on monocultures of Lolium perenne (G) or Trifolium repens (C) maintained at sward heights of 7-8 cm, was recorded. Bite masses, prehension biting and mastication rates were similar between treatments (211 vs. 230 mg DM prehension bite-1, 61 vs. 55 prehension bites and 11 vs. 13 mastications, min-1 for G and C, respectively). DM intake rates were 12.9 g min-1 for both treatments. Animals grazed longer (536 vs.436 min) and ruminated longer (526 vs. 267 min-1) on G compared with C. Daily intakes were 6.9 vs.5.6 kg DM for G and C. Growth rates for G and C were similar (0.97 vs 0.99 kg live weight d-1). Grass had a lower digestibility than clover (DOMD 60 vs. 77%). It is suggested that cattle have higher intake rates than do sheep because a lower proportion of their total jaw movements are used to masticate herbage