Evaluating a Rapid Method to Determine Faecal Burden on Pasture from Grazing Cattle

Abstract

Grazing livestock excrete large volumes of faecal material on pasture. Understanding the magnitude of this faecal burden is important for attributing sources of agricultural pollutants to different spatial and temporal scales. This field-based study evaluated the utility and transferability of a rapid approach often used in plant ecology (the line intercept method (LIM)) for estimating faecal burden from grazing cattle on pasture. Results from the LIM were of equivalent magnitude, with no significant difference observed, to those derived from more time-consuming sampling of faecal material from pasture using a quadrat-style methodology (herein termed burden sampling). However, the variability in estimates using the LIM was much larger (839-7,079 kg fresh weight faeces over the 50,000 m2 field) compared with estimates provided by the burden sampling of pasture at 0.2 % area sampled (1,616-3,979 kg/50,000 m2), 0.4 % area sampled (1,753-2,723 kg/50,000 m2) and 0.8 % area sampled (1,212-2,344 kg/50,000 m2). The LIM offers a rapid and cost-effective alternative to time-consuming sampling campaigns of faecal burden on pasture and provides estimations that are preferable to back-of-the-envelope calculations based on the over-simplification of livestock excretion rates.