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Effects of injectable trace minerals on reproductive performance of beef heifers in adequate trace mineral status

Springman, S.A., Maddux, J.G., Drewnoski, M.E., Funston, R.N.
The Professional animal scientists 2018 v.34 no.6 pp. 649-652
beef cattle, bulls, controlled internal drug release devices, copper, corn, cows, crop residues, feedlots, heifers, liver, manganese, pregnancy rate, reproductive performance, selenium, weaning, winter, zinc, Nebraska
Red Angus–based, May-born heifers (n = 799) at 2 locations (Maddux Ranches, Wauneta, NE) were used to evaluate an injectable trace mineral on reproductive performance. Following October weaning, heifers were backgrounded in a feedlot until reaching a BW of 295 kg and then moved to native range at location 1 (n = 125) or location 2 (n = 286) in early March. Additional heifers (n = 388) grazed corn residue with cows, weaned in April, and were backgrounded until reaching 295 kg and then transported to locations 1 and 2 by early June. Free-choice mineral was available at both locations. Initial liver mineral status before treatment (n = 22; 307 kg) was adequate and not different (P > 0.26) among winter locations (copper = 146 μg/g, manganese = 9.22 μg/g, selenium = 1.54 μg/g, and zinc = 115 μg/g). Heifers were synchronized with a 14-d controlled internal drug-release (CIDR) timed-AI protocol and injected with a trace mineral (5 mL, Multimin 90; MM, n = 399) or not (CON, n = 400) at CIDR insertion. Bulls were with heifers on range 60 d following AI. The proportion of heifers pregnant within the first 21 d was not different (P = 0.32; 69 vs. 62 ± 3%; CON vs. MM) nor were those pregnant within 33 d (P = 0.57; 86 vs. 77 ± 2%; CON vs. MM) or overall pregnancy rates (P = 0.38; 95 vs. 93 ± 1%; CON vs. MM). Injectable trace mineral 33 d before AI did not influence reproductive performance in heifers with adequate trace mineral status.