Diurnal patterns of rumen fill in grazing sheep

B.C. Thomson, G.J. Cruickshank, D.P. Poppi, A.R. Sykes

Animal Science Group, Lincoln College, Canterbury

Proceedings of the New Zealand Society of Animal Production. 1985, 45: 117-120

Four wethers fitted with large rumen cannulae grazed Huia white clover or Matua prairie grass for 14 to 21 days. Animals grazed longer on the prairie grass than on the white clover (8.9 v 5.8 h). Major grazing periods were evident in the morning and afternoon, although the animals generally spent more of each hour in razing during the afternoon.

Rumen fill (volume, wet weight and dry weight) showed diurnal patterns of change similar to the grazing pattern. The maximum level of rumen fill (9.5 and 7.0 g DM/kg live weight (W) on grass and clover respectively) was observed at the end of the afternoon grazing period and the minimum at 0900 h on the grass (5.2 g DM/kg W) and at 1300 h on the clover (3.9 g DM/kg W).

The implication of these results is that the intake of these roughages is less than that which is physically possible if the animal ate consistently to its maximum fill.

Keywords: NZSAPAB; sheep; white clover; prairie grass; wet weight; dry weight; rumen; volume