Date of Graduation

8-2017

Document Type

Thesis

Degree Name

Master of Science in Animal Science (MS)

Degree Level

Graduate

Department

Animal Science

Advisor

Jeremy G. Powell

Committee Member

Elizabeth B. Kegley

Second Committee Member

Rick W. Rorie

Keywords

Beef Heifer, Development, Hydroxy Trace Minerals, Sulfate Trace Minerals, Trace Mineral Sources

Abstract

Crossbred heifers (n = 286, 255 ± 4.5 kg initial BW, 295 ± 16.5 d of age) were used over a 2-yr period to determine the effects of mineral source on beef heifer development at 2 locations (n = 71 and n = 72, Fayetteville, blocks 1 and 4; n = 72 in each of 2 breeding groups, Batesville, blocks 2 and 3). Heifers were stratified based on initial BW, age, health, prior research projects, and sire, and then assigned to 6 groups of 12 heifers, that were assigned randomly to 1 of 2 trace mineral treatments. The 2 treatments were trace mineral supplementation (Cu [74 mg/d], Mn [294 mg/d], and Zn [221 mg/d]) as 1) sulfate or 2) hydroxychloride sources. Treatments were delivered through mineral and vitamin supplements provided free choice and formulated for a consumption rate of 113 g/d. Treatments began on d 0, and the breeding season began on d 112 and d 105 (blocks 1 and 4 respectively). After a synchronization period and a 10 d eligible period for artificial insemination, heifers were exposed to bulls for 50 d. At d 130 (block 2) and d 146 (block 3) heifers were exposed to bulls for 60 d. The trail concluded on d 224 (block 1), d 227 (block 4), d 252 (block 2), and d 268 (block 3). During the trial, BW at 28-d intervals, mineral disappearance, health records, and reproductive efficiency data were recorded. At the end of each trial, pregnancy was confirmed by the presence of Pregnancy-Specific Protein B concentrations in blood. No treatment differences (P ≥ 0.52) were detected in BW or ADG. There was no significance for greater mineral disappearance between mineral sulfate and hydroxychloride treatments (P = 0.46) There were no differences in the percentage of heifers treated for bovine respiratory disease (P = 0.77) or foot rot occurrence (P = 0.57) between sulfate and hydroxychloride treatments. Trace mineral source did not affect overall pregnancy rates (P = 0.85). Therefore, supplementing either a sulfate or hydroxychloride source of Zn, Cu, and Mn to developing beef heifers resulted in similar performance.

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