Impact of Shade in Beef Feedyards on Performance, Body Temperature, and Heat Stress Measures

A study using crossbred steers (n= 1677; initial BW = 372 kg, SD = 47) was conducted at a commercial feedyard in Eastern NE to determine the effects of shade on cattle performance, body temperature, and cattle activity. Two treatments were evaluated using a randomized complete block design (n=5 blocks based on arrival). Treatments were assigned randomly to pen and consisted of 5 pens without shade (OPEN) and 5 pens with shade (SHADE). Steers were allowed 38 m²/steer of pen space and shaded area was 2.8 and 4.2 m²/steer. Cattle were assigned to pen based on processing order, switching the sort gate after every third steer. Body temperatures were collected throughout the trial using the Smart Stock rumen bolus system and Quantified Ag biometric sensing ear tags on a subset of cattle (20 to 30 steers per pen based on pen size). Panting scores were collected on those same subsets of steers a minimum of twice weekly from June 8 until August 21. No significant differences were observed for ADG (P = 0.29), DMI (P = 0.31), G:F (P = 0.85), or carcass characteristics (P > 0.24). Two heat events and one cool event were defined for the feeding period based on adjusted temperature-humidity index, with Event 1 from June 3 to June 12, Event 2 from July 6 to July 24, and the cool event from August 6 to August 18. In addition, overall trial data (April 28 to September 8) were compared for temperature and activity when all cattle were in pens simultaneously. During Event 1, cattle in SHADE had greater DMI (P = 0.02) and tended to have lower panting scores (P = 0.13) than cattle in OPEN. During Event 2, SHADE cattle had greater DMI (P < 0.01) and lower panting scores (P < 0.01). The cool event also saw greater DMI (P < 0.01) and lower panting scores (P < 0.01) for the SHADE cattle. Ear temperature for OPEN cattle was greater for Event 1 from 1100 to 1700 hours and greater for Event 2 from 1200 to 2000 hours (P < 0.05), but were not significantly different for the cool event (P=0.95) suggesting cattle in shaded pens were cooler during the afternoon. During the entire feeding period, OPEN cattle ear temperature was greater than SHADE cattle (P < 0.01) while movement was not different between the two treatments (P = 0.93).

Key Words: Biometric sensing, Heat stress, Shade