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Effect of trace mineral injection on growth and trace mineral status of nursing beef calves
The objective of this experiment was to determine the effect of an injectable trace mineral (TMI) on the growth and trace mineral status of nursing beef calves. Over two years, cows (n = 200 each year) received either a TMI (0.90mL/91 kg BW) of Multimin90 containing Cu, Se, Mn, and Zn; or no injection (CON) 50 d before the start of the calving season. Throughout the two years all cows were given access to a free-choice mineral containing Cu, Se, and Zn. Calves (n = 194 TMI, n = 187 CON) were assigned to the same treatment as their dams and TMI calves received 1 mL of Multimin90 at one day of age (DOA). In both years cows assigned to TMI received a second injection at branding. In year one of the study calves in the TMI group also received injections (1 ml/45 kg BW) at branding (51 ± 1.3 DOA), and jugular blood was collected from calves (n = 40; 20 per treatment) prior to injection to determine trace mineral concentration. Data were analyzed using the MIXED Procedure of SAS with individual animal being the experimental unit. Plasma Se and Mn concentrations were increased (P ≤ 0.05) in TMI (88.8 ug Se/L and 23.1 ug Mn/L) calves when compared to CON (51.9 ug Se/L and 12.6 ug Mn/L). Plasma Zn tended to be increased (P = 0.06) in TMI (1.16 mg/L) calves compared to CON (1.00 mg/L). No effect (P = 0.54) of TMI on plasma Cu (0.90 vs 0.86 mg/L, TMI vs CON, respectively) was observed. At weaning (DOA = 195 ± 0.8), liver biopsies (n = 20 per treatment per year) were performed to determine liver trace mineral concentrations. Liver Cu was increased (P = 0.02) in TMI (187 mg/kg) compared to CON (150 mg/kg) and liver Se of TMI (0.98 mg/kg) tended (P = 0.10) to be increased compared to CON (0.88 mg/kg). There was no significant difference (P ≥ 0.24) in liver concentrations of Zn (113 vs. 108 mg/kg for TMI and CON, respectively) or Mn (11.4 vs. 12.2 mg/kg for TMI and CON, respectively). Concentrations of all trace minerals in the liver were considered adequate regardless of treatment. There was no effect (P= 0.54) of TMI on 205 d adjusted weaning weight (286 vs. 284 ± 2.5 kg for TMI and CON, respectively). Use of a TMI increased Se and Cu status but did not improve growth of calves in this study.
Keywords: calf, growth, injectable trace mineral