The effects of recording interval on the estimation of grazing behavior of cattle in a daytime grazing system

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 (<4 months old) were investigated in a daytime grazing (7 h) system utilizing a bahiagrass (Paspalum notatum Flügge) pasture (a 1.1 ha paddock and a 0.4 ha resting area). Recording intervals of 10-30 min tended to underestimate the time spent grazing and ruminating and overestimate the time spent resting by animals, whereas intervals of 1-5 min resulted in almost constant estimates. In all grazing activities, the errors of estimation became larger when the recording interval exceeded 5 min. The accuracy of estimation was higher for grazing time>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.