Effect of shade on performance, carcass quality, and welfare of finishing cattle fed a beta-adrenergic agonist in a commercial feedlot

Abstract Text:

Finishing feedlot cattle fed a beta-adrenergic agonist (n=1,395; BW=568 ± 43 kg) were used to evaluate the effects of shade on performance, carcass quality, and welfare during the summer in a Kansas commercial feedlot. Cattle were randomly assigned to 1 of 2 treatments: 1) No Shade or 2) Shade. At 26 to 53 d prior to slaughter, 7 pens of predominately black steers or heifers (4 and 3, respectively, n = 7 replications per treatment) were randomly divided and allocated to 2 pens across the feed alley from each other: 1 pen shaded and 1 pen non-shaded. Pen served as the experimental unit. Prevalence of cattle open-mouth breathing was recorded at least once weekly based on expected daily ambient temperature, humidity, and wind. Weather data were collected continually throughout the trial using a National Weather Service (NWS) weather station located 1.6 km away from the feedlot. Both pens within a replicate were shipped and harvested at the same slaughter facility on the same day. Duration of trial (mean = 38.4 d, range = 26 to 53 d) and shade area per animal within shaded pens (mean = 1.46 m²/animal, range = 1.13 m² to 1.78 m²/animal) varied between replicates. No difference in ADG was observed between shaded and non-shaded cattle (1.94 vs 1.97 ± 0.17 kg; P = 0.27). Shaded cattle had greater DMI than non-shaded cattle (10.77 vs. 10.52 ± 0.78 kg; P = 0.01). Shaded cattle tended to be less feed efficient (5.64 vs. 5.37 ± 0.25 kg; P = 0.09). No difference in HCW was noted between treatments (404 vs. 402 ± 30 kg; P = 0.30). Percentage of cattle grading choice or better tended to be greater for the shade treatment cattle (72 vs. 67 ± 8%; P = 0.12). Shade-treatment cattle had a greater dressing percentage than non-shaded cattle (65.4 vs. 65.05 ± 0.3%; P = 0.01). Shade reduced the prevalence of cattle open-mouth breathing on observation days (4% vs 1%; P < 0.001). During the relatively mild summer of 2013 (mean daily maximum temperature = 31.44, ± 4.36 C), providing shade for finishing cattle during the final 26 to 53 d on feed resulted in fewer cattle open-mouth breathing, increased dressing percentage and tended to increase quality grade. Shaded cattle had greater feed intake, however the non-shaded cattle tended to be more feed efficient and no difference in average daily gain was observed between treatments.

Keywords: Animal Welfare, Feedlot Cattle, Dry Matter Intake