13 Supplemental Trace Minerals as Amino Acid Complexed or Inorganic Sources for Beef Cattle During the Receiving Period

Abstract To investigate the effects of inorganic or amino acid-complexed sources of trace minerals (zinc, copper, manganese, and cobalt) on performance and morbidity of beef heifers during the receiving period, crossbred beef heifer calves (n = 287, initial body weight = 231 kg) arriving on 3 delivery dates were used in a 42-day receiving trial. Heifers were processed after arrival and stratified by day -1 body weights and allocated randomly to 8 pens (11 to 13 heifers/pen; total of 24 pens). Within truckload, pens were assigned randomly to dietary treatment (12 pens/treatment). Calves were housed on 0.42-ha grass paddocks, provided ad libitum access to bermudagrass hay and water, and fed grain supplements that served as the carriers of the dietary treatments. Treatments consisted of supplemental zinc (360 mg/d), copper (125 mg/d), manganese (200 mg/d), and cobalt (12 mg/d) from complexed (Availa 4, Zinpro Corporation, Eden Prairie, MN) or inorganic sources (sulfates). Cattle were observed daily for clinical bovine respiratory disease (BRD). If presenting symptoms of BRD and if rectal temperature was ≥ 40°C, cattle were deemed morbid and treated with an antibiotic according to a standard preplanned protocol. Six heifers/pen were bled to determine serum haptoglobin concentrations on days 0, 14, and 28. Statistical analyses were performed using the MIXED and GLIMMIX 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 body weights (P = 0.07). Body weights did not differ on day 0 (P = 0.82) and day 14 (P = 0.36), but heifers supplemented with complexed trace mineral sources had greater body weights on day 28 (P = 0.04) and day 42 (P = 0.05; 264 vs. 260 kg, SE = 1.8). Overall average daily gains were greater for heifers supplemented with the complexed trace mineral sources (P = 0.05; 0.78 vs. 0.70 kg, SE = 0.03). Cattle supplemented with inorganic trace mineral sources had greater BRD morbidity incidence than cattle supplemented with complexed trace mineral sources (P = 0.03; 58 vs. 46%, SE = 3.6). Medication costs were lower for heifers supplemented with complexed trace mineral sources (P = 0.05; $11.01 vs. $14.90, SE = 1.33). Haptoglobin concentrations decreased throughout the trial (day, P < 0.001), and cattle supplemented with complexed trace mineral sources tended to have lower haptoglobin concentrations (P = 0.07). In conclusion, supplementing cattle for the first 42 days after arrival with amino acid complexed trace mineral sources improved heifer performance as compared to heifers supplemented with inorganic trace minerals.