Submitted to: Society for Range Management Meeting Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: 8/17/2013
Publication Date: N/A
Technical Abstract: In order to measure the weight gains of free-ranging livestock, animals are frequently corralled and confined overnight prior to weighing. Animals may take several days to recover from this overnight loss in weight associated with dehydration and excretion of urine and feces. Quantitative estimates of the magnitude of this overnight shrink for livestock across the grazing season could provide temporal weight gain data without the associated stress of shrinking and regaining weight for the grazing animals each time they are weighed. We determined shrink losses for crossbred yearling steers grazing shortgrass steppe at the Central Plains Experimental Range (Nunn, Colorado, USA) for each of four weigh dates (June, July, August, September) in the 2009-2012 summer grazing seasons (total of 16 weighings) to assess if environmental variables including 1) average relative humidity, (2) maximum, minimum or average air temperatures, (3) number of hours where hourly average air temperatures exceeded 26.7 °C, and (4) cumulative air temperature determined by adding hourly average values for the entire shrink period influenced these shrink losses. Overnight shrink in yearlings was insensitive to environmental variables during the summer grazing season in shortgrass steppe. Mean values from the different weigh dates across the four study years provide “pencil shrink” percentages that can be used for grazing studies and land managers (8.8-9.0% shrink values for June, July and August, and 7.1% for September) in semiarid rangelands. Use of these “pencil shrink” percentages (1) eliminates the need for overnight holding of livestock in a drylot which increases animal well-being by removing stresses of losing the weight overnight and regaining this lost weight, and (2) provides an approach to more readily measure temporal weight gain data within a grazing season.