273 Impacts of commingling on health and productive responses of beef heifers during feedlot receiving. (30th November 2020)

• Record Type: Journal Article
• Authors: Wiegand, Jacob; Cooke, Reinaldo F; Brandão, Alice; Schubach, Kelsey; Colombo, Eduardo; Sowers, CiCi A; Duff, Glenn; Gouvea, Vinicius N
• Is Part Of: Journal of animal science. Volume 98(2020)Supplement 4
• Page Start: 193
• Page End: 194
• Publication Date: 2020-11-30
• Subjects: Livestock -- Periodicals; Livestock; Electronic journals; Periodicals; 636.005
• DOI: 10.1093/jas/skaa278.356
• Languages: English
• ISSNs: 0021-8812

Abstract

Abstract: This experiment compared physiological, health, and performance responses of beef heifers assigned to different commingling schemes (1, 2, or 4 sources/pen) during a 56-d feedlot receiving period. Ninety-six recently weaned Angus-influenced heifers were purchased from a commercial auction facility. Heifers originated from 4 cow-calf ranches, and were reared in the same herd within each ranch since birth. Heifers were loaded by source into commercial livestock trailers at the auction yard, and transported for 8 h to stimulate the stress of a long haul. Heifers were not mixed with cohorts from other sources prior to and at the auction yard. Upon arrival at the receiving yard (d -2), shrunk body weight (BW) was recorded, and heifers were maintained in 4 paddocks by source with ad libitum access to hay, water, and a mineral supplement for 36 h. On d 0, heifers were ranked by source and shrunk BW and allocated to 1 of 24 drylot pens (4 heifers/pen) containing: 1) heifers from a single source (NOCOM, n = 8 pens), 2) heifers from 2 sources (COM2, n = 8 pens), or 3) heifers from 4 sources (COM4, n = 8 pens). From d 0 to 55, heifers had free-choice access to water and a total-mixed ration. Heifers were assessed for bovine respiratory disease (BRD) signs and feed intake was recorded from each pen daily. Blood samples were collected from all heifers on d 0, 6, 13, 27, 41, and 55, and shrunk BW (after 16 h of water and feed withdrawal) was collected on d 56 for average daily gain (ADG) calculation. Final shrunk BW and ADG did not differ (P ≥ 0.83) between NOCOM, COM2, and COM4 heifers (0.85, 0.88, and 0.82 kg/d of ADG, respectively, SEM = 0.08). No treatment effects were detected (P ≥ 0.77) for feed intake and feed efficiency, as well as plasma concentrations of haptoglobin and cortisol. No treatment differences were noted (P ≥ 0.49) for morbidity (53.1, 68.7, and 56.2% of NOCOM, COM2, and COM4 heifers diagnosed with BRD, respectively; SEM = 9.7) or mortality during the experiment. A similar (P ≥ 0.97) proportion of NOCOM, COM2, and COM4 heifers diagnosed with BRD required at least two treatments to recover from sickness. In turn, a third treatment was not required for NOCOM heifers, which was less compared with COM4 (P = 0.05) and similar (P = 0.23) compared with COM2 heifers. Perhaps the number of heifers assigned to commingled pens, and resultant pre-existing social groups, was not sufficient to stimulate the stress reactions caused by social destabilization.