Case Study: The Effects of Severe Winter Weather on Net Energy for Maintenance Required by Yearling Steers

Severe winter storms in southeast Colorado in December of 2006 and January 2007 resulted in severe economic losses for the cattle feeding industry. Two hundred fourteen steers were weighed on December 26, 2006, and average BW (minus 4% pencil shrink) was 558 kg ± 21.7. Over the following 58-d period there was a 7.0% death loss and ADG was −0.13 kg ± 0.21. Average steer BW (minus 4% pencil shrink) was 550 kg ±18.7 on February 22, 2007. Total DM delivered was 53,436.7 kg and average NEm concentration in the diet was 2.263 Mcal/kg DM. Daily DMI averaged 9.67 kg/d per head. Average shrunk BW (SBW) was 554.1 kg and average empty body weight (497.7 kg), empty body gain (−0.00686 kg/d), and retained energy (−0.0283 Mcal/d) were calculated from NRC (2000) equations. The required NEm was 21.9176 Mcal/d per head or 0.1919 Mcal/kg of SBW0.75 These data indicate that NEm required during and in the aftermath of a major winter weather event may be 2.5 fold higher than NEm required (0.077 × SBW0.75) under thermal neutral conditions. Calculations of lower critical temperature and external insulation indicate that the insulation value of the hair coat may have been destroyed by the moisture, mud, and snow following the storm.