PS11-12. Interval from Feedlot Arrival to Initial Processing: Effects on Health and Performance of Feedlot Receiving Cattle.

Abstract This experiment compared different rest periods upon arrival (0 h, 24 h, or 72 h), and their subsequent effects on health and productive responses of feedlot cattle. Two hundred and forty Angus-influenced steers were obtained from 3 different cow-calf herds (80 steers/herd) and road transported for 1,200 km (18 h) to stimulate the stress of road-transport. Steers were weaned immediately prior to transport. Upon arrival at the experimental receiving yard, steers were ranked by source and weaning body weight (BW) and assigned to 1 of 3 treatments: 1) initial processing upon arrival (NOREST), 2) rest for 24 h prior to initial processing (24REST), and 3) rest for 72 h prior to initial processing (72REST). Steers were housed in 24 drylot pens (10 steers/pen, with 2 or 3 steers/source; 8 pens/treatment) after initial processing for a 90-d receiving period. The initial processing included tagging, vaccination, deworming, and application of growth-promoting implant. Steers assigned to NOREST immediately received the initial processing upon arrival. The 24REST and 72REST steers were maintained in 4 separate paddocks (2 paddocks/treatment) for 24 or 72 h, respectively, prior to initial processing with free-choice access to long-stem hay, water, and mineral-vitamin supplement. All steers were revaccinated against respiratory pathogens on d 14. Steer BW was recorded upon arrival and used as initial BW. Final BW (shrunk) was obtained on d 91 after 16-h of feed and water deprivation. Pen feed intake and symptoms of bovine respiratory disease (BRD) were evaluated daily. Blood samples were collected at initial processing (d 0) and on d 14, 28, and 56. Hair samples were collected from the tail switch on d 0, 14, and 28. Initial and final BW did not differ (P ≥ 0.62) among NOREST, 24REST, and 72REST (271, 273, and 269 kg of initial BW, SEM = 3; 371, 374, and 370 kg of final BW, SEM = 4). Average daily gain and mean feed intake also did not differ (P ≥ 0.33) among NOREST, 24REST, and 72REST (1.35, 1.35, and 1.32 kg/d of average daily gain, SEM = 0.76; 8.31, 8.16, and 8.45 of feed intake, SEM = 0.13). No differences among NOREST, 24REST, and 72REST were detected for incidence of BRD symptoms (12.5, 17.5, and 23.5%, respectively; SEM = 5.2). No treatment effects were detected (P ≥ 0.37) for plasma concentrations of antibodies against respiratory pathogens or hair cortisol concentrations. In summary, length of rest period upon feedyard arrival did not impact health and performance of receiving cattle.