Forage and Weather Influence Day versus Nighttime Cow Behavior and Calf Weaning Weights on Rangeland

Abstract

We determined the effects of two forage allowance levels (LOW vs. HIGH) and weather conditions on daytime and nighttime movement patterns of young rangeland-raised cows. We also investigated whether calf weaning weights (n = 42) were significantly related to postcalving movement patterns of the dam. Global positioning system data were collected over 4 years by recording 5-min interval locations of 52 crossbred cows grazing a 146-ha woodland/grassland pasture for approximately 20 days. The pasture was stocked moderately in 2004 (73 AUMs) and 2005 (78 AUMs) and lightly in 2006 (34 AUMs) and 2007 (32 AUMs). Estimated forage allowance was lowin 2004 and 2005 (347 and 438 kg herbage · cow-1, respectively) and high in 2006 and 2007 (1104 and 1884 kg herbage · cow-1, respectively). We calculated distance traveled, path sinuosity, woodland preference, and area explored for each cow during 24 h (D + N), daytime (DAY), and nighttime (PRE dawn and POST sunset) periods. Cows in LOW traveled farther than counterparts in HIGH during D + N and DAY (P < 0.01) periods but traveled shorter or similar distances during POST (P = 0.05) and PRE (P = 0.29) nighttime periods, respectively. Cows in LOW exhibited more sinuous movement paths than cows in HIGH during DAY, PRE, and POST periods (P < 0.01). Cows in LOW explored larger areas and spent more time in woodlands than counterparts in HIGH (P < 0.01). Weather factors associated with thermal comfort affected daily variation in both daytime and nighttime movement patterns of cows. A dam's movement patterns in the weeks immediately following calving were correlated (P < 0.01) with steer but not heifer calf WW. Moderate stocking rates (LOW treatment) induced behaviors that resulted in higher woodland preference and heavier steer calf WW. © 2016 The Society for Range Management. Published by Elsevier Inc. All rights reserved.