2017-06-022017-06-022017-052017-05May 2017http://hdl.handle.net/2346/72627The objective of the current research was to determine the effects of confined versus conventional cow-calf management systems on calf health. In the first experiment, the goal was to evaluate production parameters at the time of calving, calf morbidity/mortality, and growth performance in two variations of confined cow-calf management systems relative to a conventional, pasture-based system from the time of calving until weaning. A total of 250, British x Continental crossbred, pregnant, first-calf heifers were blocked by breeding service type (AI vs. natural) and assigned to one of three treatments within a randomized complete block design: 1) Conventional, pasture-based calving system (PAS) (n = 84; BW = 505.05 ± 40.51 kg); 2) Continuously confined calving system (CONF) (n = 83; BW = 507.36 ± 44.89 kg); and, 3) Sandhills calving system (SH) (n = 83; BW = 502.51 ± 54.37 kg). Immediately prior to calving, the PAS assigned heifers were moved to an 80-acre, split-fenced pasture containing dormant, improved grasses. The CONF cattle were assigned to feedlot pens (2 pens/block; 20-21 hd/pen) and remained in this location from the beginning of calving until the time of weaning. The SH cattle began in pens identical to CONF; however, after half of the heifers in the pen calved or no more than 14 d from the beginning of calving, remaining bred heifers were moved to a clean pen (4 pens/block; 10 to 11 hd/pen). Supplemental colostrum was provided only to calves born in confinement. The relative proportion of normal and minimally assisted births versus extremely difficult births was increased in the confined treatments (P = 0.03). The PAS calves experienced a greater incidence of failure of passive transfer when compared to calves born in the SH treatment (P = 0.01) and tended to differ from calves born in the CONF group (P = 0.06). Calf morbidity rates differed among all treatments (P ≤ 0.01) (CONF, 68.49%; SH, 47.37%; PAS, 2.47%). Furthermore, the incidence of calf scours was reduced in SH vs. CONF (P = 0.03). Mortality was increased in confined treatments relative to PAS (P < 0.01). At weaning, antibody titers against BVD1 and BRSV were reduced in PAS compared to confined treatments (P ≤ 0.04). Calves in the PAS treatment demonstrated greater ADG and weaning weight relative to the confined treatments (P ≤ 0.03). Data from this evaluation suggest that impaired health and subsequent growth performance of calves born in a feedlot setting could dramatically influence the profitability of confined cow-calf operations. In the second experiment, the objective was to characterize the immune and clinical response of calves that were raised in two variations of confined management systems relative to a conventional system when challenged with infectious bovine rhinotracheitis (IBR) and Mannheimia Haemolytica (MH). Preconditioned steer calves (n = 24) were used within a completely randomized design to evaluate the effects of management systems. The previously imposed treatments were: 1) Conventional, pasture-based production system (PAS) (n = 8; BW = 272.90 ± 27.51 kg); 2) Continuously confined production system (CONF) (n = 8; BW = 234.24 ± 17.74 kg); 3) Sandhills production system (SH) (n = 8; BW = 241.95 ± 35.83 kg). Calves were challenged with an intranasal dose of IBR and placed in a barn containing individual stalls. After 72 h, cattle were administered an intratracheal dose of MH. At -72, 0, 2, 6, 12, 24, 48, 72, 168, and 336 h relative to MH inoculation, rectal temperature (RT) was measured and cattle were assigned a clinical severity score (CS). Additionally, peripheral blood was collected via jugular venipuncture at strategic time points for the evaluation of: 1) proinflammatory cytokines; interleukin-1 beta (IL1), interleukin-6 (IL6), tumor necrosis factor-alpha (TNFa), and interferon-gamma (INFy); 2) haptoglobin; 3) hematology; and, 4) antibody titers. Calves from the SH treatment exhibited the greatest RT following immune challenge when compared to either CONF or PAS calves (P < 0.01). Furthermore, CONF calves recorded greater RT when compared to the PAS treatment (P < 0.02). Calves in the SH treatment exhibited the greatest CS over time (P < 0.01). The concentration of INFy, IL1, and IL6 was reduced in PAS cattle when compared the confined treatments (P ≤ 0.01). Calves in the SH treatment demonstrated the greatest concentration of haptoglobin when compared to the PAS and CONF groups (P ≤ 0.01). A treatment related tendency was detected (P < 0.01); SH calves tended to demonstrate reduced VN titers 7 d post-MH relative to the CONF and PAS treatments. These results indicate that management systems can exert an influence on immune responsiveness. Cattle from the SH treatment exhibited the most apparent difficulty coping with disease. This conclusion was supported by increased RT, CS, and haptoglobin concentration; furthermore, SH cattle tended to demonstrate a weaker antibody response to IBR. Collectively, both experiments indicate that considerable challenges exist when operating the cow-calf enterprise in confinement; thus, management strategies to improve performance in these management systems should be further investigated.application/pdfengBeef cattleCalf healthConfined cow-calfImmunityDissertation2017-06-02Unrestricted.