Methodology for studying the behavior of calves in confinement during the post-weaning phase

Abstract

Twelve 60-day old, 120 kg mean initial age and weight, post-weaning Holstein calves were randomly distributed between two treatments (concentrates in meal or pellet form). The diet consisted of hay ad libitum and 2 kg daily of concentrates. Each animal was observed at six different time intervals: 5, 10, 15, 20, 25, and 30 minutes. A repeated measure of experimental units design, in a 2 x 6 factorial arrangement was used. The objective was to identify the most adequate time intervals to study ingestive behavior compared to the standard 5-minute observation interval scale. Treatments had no effect on the variables studied. Feeding, ruminating and idle activities duration times did no differ (P>0.05) among time interval scales. However, only in the 5- and 10-minute scales were the number of discrete periods of feeding, ruminating and idleness and their duration, statistically the same (P>0.05). Use of scales of up to 10-minute intervals between observations is recommended for this type of experiment (Pt)