To investigate effects of inorganic or complexed trace mineral source (zinc, copper, manganese, and cobalt) on receiving period performance and morbidity, crossbred beef heifer calves (n = 287) arriving on three delivery dates were used in a 42-d receiving trial. Heifers were processed after arrival, stratified by day -1 body weights (BW) and allocated randomly to eight pens (11 to 13 heifers/pen, 24 pens total). Within truckload, pens were assigned randomly to dietary treatment (n = 12 pens/treatment). Heifers were housed on 0.42-ha grass paddocks, provided ad libitum bermudagrass hay and provided dietary treatments in grain supplements fed daily. Treatments consisted of supplemental zinc (360 mg/d), copper (125 mg/d), manganese (200 mg/d), and cobalt (12 mg/d) from complexed (Zinpro Availa 4, Zinpro Corp. Eden Prairie, MN) or inorganic sources (sulfates). Heifers were observed daily for clinical bovine respiratory disease (BRD). If presenting BRD symptoms and rectal temperature ≥ 40 °C, heifers were deemed morbid and treated with antibiotics. Six heifers/pen were bled to determine serum haptoglobin concentrations on days 0, 14, and 28. Liver biopsies were taken on day 5 ± 2 and 43 ± 1 from three calves selected randomly from each pen for mineral status comparisons. Statistical analyses were performed using the MIXED, GLIMMIX, and repeated measures procedures of SAS 9.4 with truckload as a random effect and pen within truckload specified as subject. There tended to be a treatment by day interaction for BW (P = 0.07). Heifer BW did not differ on day 0 (P = 0.82) and day 14 (P = 0.36), but heifers fed complexed trace minerals had greater BW on day 28 (P = 0.04) and day 42 (P = 0.05). Overall average daily gains were greater for heifers fed complexed trace minerals (P = 0.05; 0.78 vs. 0.70 kg, SE = 0.03). Heifers supplemented with inorganic trace minerals had greater BRD incidence (P = 0.03; 58 vs. 46%, SE = 3.6). Haptoglobin concentrations decreased throughout the trial (P < 0.001), and heifers fed complexed trace minerals tended to have a decrease in haptoglobin concentrations (P = 0.07). The source of trace mineral supplementation had no effect (P ≥ 0.20) on liver mineral concentrations and there were no treatment × day interactions (P ≥ 0.35). In conclusion, supplementing diets for the first 42 d after arrival with complexed trace mineral sources improved heifer performance as compared to heifers supplemented with inorganic trace minerals.
Keywords: beef cattle; complexed trace minerals; receiving.
Issues associated with health and management of newly received cattle continue to pose significant animal welfare and economic challenges for the beef industry. Diagnosis of bovine respiratory disease, accompanied with poor growth performance, can be addressed by nutritional intervention in receiving cattle. Trace mineral inclusion in receiving rations is vital to calf performance. There are numerous sources of trace mineral supplements that exist commercially for cattle and their effects on immune function, growth, and performance measures were evaluated. Organic trace mineral supplements are being used in replacement of inorganic salts due to potentially greater bioavailability and functionality. An organic source that is commonly used are amino acid complexes. Replacing inorganic sources with complexed sources of trace minerals (zinc, copper, manganese, and cobalt) improved growth performance and decreased sickness during the 42-d receiving study.
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