104. Effects of Timing of Mineral Drench Administration on Performance, Acute-phase Protein, and Mineral Status of Grazing Beef Calves.

Abstract Single-use, pulse-dose products can be an alternative to boost calf mineral status at challenging management events, such as weaning, transportation, and commingling. The use of oral drenches as additional supplementation is a convenient tool to provide trace minerals at strategic intervals. It was hypothesized that providing a trace mineral drench at different time points would be an effective strategy to improve the trace mineral status of calves and subsequent performance at and post-weaning. Thus, the objective of this study was to evaluate the effects of a trace mineral drench that provides Co, Cu, Mn, Se, and Zn, along with vitamin E, at strategic intervals. Sixty crossbred (Angus x Hereford) calves from the herd of Eastern Oregon Agricultural Research Center (EOARC) were selected during their dams’ breeding season and randomly allocated into 1 of 4 treatments: 1) Control, no drench administration; 2) Breeding, with drench administered at breeding; 3) Weaning, with drench administered at weaning; and 4) Breeding + Weaning, with drench administered at breeding and again at weaning. Drench was administered according to the manufacturer’s recommendation at 5 ml/45 kg of body weight (BW). Liver samples (n = 23) and BW were collected from calves at drench administration throughout the study. After weaning, calves were preconditioned for 45 days, and final BW and a liver sample were collected at the end of the preconditioning. Blood samples were collected at, weaning, and on days 1, 3, 7, 14, 21, and 45 post-weaning to evaluate acute phase proteins. Preliminary data for BW, mineral status, and haptoglobin concentration were analyzed using MIXED procedures of SAS (SAS Inc., Cary, NC, USA). Statistical significance was set at a P ≤ 0.05. No effects of treatment (P ≥ 0.67) were observed for calf BW at any of the time points recorded (113 ± 5 kg; 225 ± 9 kg; 250 ± 9 kg breeding, weaning, and end of preconditioning, respectively). Of the trace minerals evaluated, a tendency for treatment effect (P = 0.08) was observed for Cu status of calves at weaning, where calves assigned to receive drench at Breeding tended to have or had greater (P ≤ 0.06) Cu status at weaning than calves assigned to all other treatments (21, 53, 27, and, 42 ± 12 mg/kg for Control, Breeding, Weaning, and Breeding + Weaning treatments, respectively). An effect of time (P ≤ 0.01) was observed for plasma haptoglobin, where plasma haptoglobin peaked (0.838 ± 0.25 mg/mL) on d3 post-weaning for all calves regardless of treatment. Although no effects were observed for calf growth, the use of drench at the dam’s breeding can be a convenient alternative to enhance the Cu status of calves at weaning, especially with forages with low Cu concentrations.