Herbage intake by grazing dairy cows

An extensive review of the literature is given of- nine possible methods for estimating herbage intake by grazing ruminants, with special attention to the sward-cutting and indirect animal methods- the factors determining the herbage intake by grazing ruminants.The herbage intake of lactating cows was determined in 151 trials at Lelystad from 1976 to 1979. The pre-cut swards consisted predominantly of perennial ryegrass. A swardsampling technique was used for estimating herbage intake by cows grazing swards for 3 or 4 days (with corrections for herbage accumulation during grazing). If herbage samples were cut both with a motor scythe and a lawn~mower accurate intake figures could be obtained.It was shown that there were no significant effects of higher levels of areic mass of herbage (by taking longer rest periods) on daily organic matter intake of herbage neither by grazing nor by stall-fed cows. However in early summer daily intake of nutrients and milk production decreased at increasing maturity; in late summer these effects were not significant. Higher levels of daily herbage allowance had significant positive effects on daily intake of organic matter of nutrients from herbage and ondaily milk production per grazing animal. High amounts of residual herbage (achieved by higher levels of daily herbage allowance) increased net regrowth of herbage, especially in early summer.At a mean allowance level of 23 kg d -1above 4.5 cm our grazing cows consumed 13.6-14.8 kg d -1of organic matter if no concentrates were fed. This was sufficient, at the quality of herbage as in our trials, for a daily 4%-fat corrected milk production of 22-23 kg.