The Effects of Recording Interval on the Estimation of Grazing Behavior of Cattle in a Daytime Grazing System

M Hirata,W Otozu,T Iwamoto,D Kiyota

doi:10.5713/ajas.2002.745

Abstract

The effects of recording interval (1, 2, 3, 4, 5, 10, 15, 20 and 30 min) on the estimation of some grazing behavior variables in beef cows and calves ( rumination time>resting time. An increase in recording interval always decreased estimates of the distance walked by animals. It was concluded that recording intervals of 1-5 min provide reliable estimates of the time spent grazing, ruminating and resting. It was also concluded that positioning of animals at 1 min intervals may provide estimates of walking distance with acceptable bias toward underestimation. (Asian-Aust. J. Anim. Sci. 2002. Vol 15, No. 5 : 745-750)

Highlights

Measurement of grazing behavior of animals is an important component of many researches of grazing systems
The estimates of the distance walked by the cows and the calves during the 7 h grazing period always exponentially decreased as the recording interval increased
The relative estimates of the walking distance showed that an increase in the recording interval even from min to 5 min sharply decreased the estimates

Summary

Introduction

Measurement of grazing behavior of animals is an important component of many researches of grazing systems. Time spent by animals in grazing activities such as grazing, rumination and resting reflects climatic and pasture (availability and quality) conditions and physiological states of animals, and relate to the performance of animals In the direct observation method, estimates of the time spent in grazing activities are often derived by using an interval sampling technique, mainly because the technique is less difficult to conduct, less laborious and as accurate as the continuous monitoring of activity. Gary et al (1970) showed that observations at 15 min intervals provide a reliable sample of characters of a continuous nature (e.g. grazing). The frequency of observation needed to obtain reliable estimates depends mainly on the Received August 27, 2001; Accepted December 20, 2001 occurrence nature (continuous or discrete event) and occurrence duration of activities and the duration of the grazing period

Methods

Results

Conclusion