Fine-scale spatial distribution of herbage mass, herbage consumption and fecal deposition by cattle in a pasture under intensive rotational grazing

Abstract

Herbage mass, herbage consumption and fecal deposition by animals were monitored for 2 years in 182 fixed locations (0.5 × 0.5 or 1 × 1 m) in a sown pasture (1.1 ha) grazed rotationally by cattle (42-45 animals). Fecal deposition was more spatially variable (higher values of coefficient of variation) than herbage mass and consumption, with consistently significant bias from the normal distribution in both skewness and kurtosis. In terms of spatial pattern, herbage mass and consumption were always or almost always spatially heterogeneous (nonrandom spatial pattern), while fecal deposition was less frequently heterogeneous or usually homogeneous (random spatial pattern). The spatial heterogeneity in herbage mass was interpreted as being created in the early grazing season possibly through spatial heterogeneity in soil-related factors, and maintained until the late grazing season mainly by herbivory where the animals always left more herbage uneaten at locations with higher pre-grazing herbage mass. Even when cumulated for 2 years (56 days of grazing), herbage consumption and fecal deposition were still considerably spatially variable. Such nonuniform cumulation of animal impacts, however, is not likely to have a negative effect on the grazing system (paddock as the major grazing area) because (1) the animals almost always consumed more herbage from locations with higher herbage mass, resulting in a less variable degree of utilization (consumption/production) across the paddock; (2) fecal deposition on the paddock was not abundant, due to the concentration of feces in the resting area adjoined; and (3) fertilizer was regularly applied to the paddock as management. © 2010 The Ecological Society of Japan.