The influence of pasture and animal factors on the consumption of pasture by grazing sheep

Abstract

Interrelations of animal and pasture factors to account for variance in (i) the time spent grazing (GT, H/day) and (ii) the rate of eating (IR, OM/h) in data collected over 2.5 years on Corriedale sheep (adult castrated males) grazing pasture of mixed perennial/annual species in south-western Victoria were examined by sequentially adding factors and analysing in nonlinear regression relationships. Three plant and two animal factors accounted for almost 80% of the variance (100R2) in the GT of sheep grazing on green pasture in the period from March to November (n = 176). Five factors, including a stress factor related to environmental conditions, accounted for 82.5% of the variance in IR of sheep grazing through the green pasture period from March to December (n = 192). Pasture factors associated with organic matter digestibility were also examined. Total pasture mass (H, t DM/ha) and the green proportion of the pasture (G, %DM) accounted for 74.6% of the variance in D (n = 232). The implications of these relationships for developing an understanding of the biological basis for intake control and compensatory growth of animals are discussed.