Influence of Time of Day On Live Weight Measurements for Feedlot Steers

Abstract

Abstract Three trials were conducted to evaluate the influence of time of day on live weight (LW) measurements of feedlot steers. Trial 1 was initiated November 30, 1988 and involved 15 crossbred steers that were housed and fed individually. Trial 2 was initiated February 28, 1989 and involved 75 crossbred steers that were housed and fed in groups of 5. Trial 3 was initiated June 13, 1989 and was otherwise similar to Trial 2. Weighing times were 0400, 0800 and 1200 with periods between weighing of 7 d. Treatments were assigned to individual steers or pen groups in a replicated 3 × 3 latin square arrangement. In Trial 1, there was a linear decrease (P < .01) in LW averaging 1 kg/h for measurements taken between 0400 and 1200. In Trial 2, both linear (P < .01) and quadratic (P < .05) responses in LW to weighing time were detected. Live weight decreased .75 kg/h between 0400 and 0800, similar to what was observed in Trial 1, but between 0800 and 1200 LW remained unchanged. In Trial 3, only a linear (P < .01) response of LW to time was detected. However, as with Trial 2, the greater rate of decrease in LW appeared to occur between 0400 and 0800 (averaging 1 kg/h). Differences between trials in pattern of water consumption were related to differences in ambient temperature. Time of day had a dramatic effect on LW of feedlot steers. Measurements of LW taken within the later morning hours are more likely to be affected by water intake than measurements taken during the earlier morning time period (0400 to 0800).