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Effect of injectable trace mineral supplementation in yearling bulls on serum and semen trace mineral levels and reproductive parameters
We hypothesized that administration of an injectable trace mineral would cause a short-term increase in circulating trace mineral concentrations, but not alter semen quality nor ability to pass a breeding soundness exam (BSE). Sixteen Hereford, 52 Angus, and 22 Simmental bulls were blocked by breed and stratified by age (277±20 d) and weight (377±42 kg) and administered s.c. either a commercially-available trace mineral supplement (TM; n=45; 15 mg Cu/mL, 60 mg Zn/mL, 10 mg Mn/mL, and 5 mg Se/mL) (MultiMin 90, MultiMin USA, Inc., Ft. Collins, CO) or sterilized saline (Control; n = 45) at 1mL/45 kg BW. Bulls were maintained in a drylot and fed a grower ration that included trace minerals at NRC recommended levels. Blood was collected via jugular venipuncture immediately before treatment (h 0) and at 8 and 24 h. BW and scrotal circumferences were measured on the day of treatment (d 0) and d 20, 42, 59, and 91. Semen was collected via electroejaculation on d 42 and 91 and a BSE conducted on d 91. Serum samples from h 0, 8, and 24 and semen samples d 42, and 91 on a subset of 26 bulls per group were analyzed using inductively coupled mass spectroscopy for concentration of Cu, Zn, Mn and Se. Data were analyzed using PROC MIXED, PROC GLIMMIX, and PROC FREQ in SAS with fixed effects of treatment, breed, and time of sampling and interactions with bull as experimental unit. TM and Control bulls had similar scrotal circumferences and BW throughout the trial (P ≥ .10). Time and treatment interacted (P < .01) to affect serum trace mineral concentrations with TM bulls having greater (P < .01) trace mineral concentrations at 8 h post-treatment than Control bulls. Semen trace mineral concentrations on d 42 and 91 were similar (P ≥ .05) between TM and Control bulls Sperm motility, percent normal morphology, concentration, and percentage proximal droplets improved (P < .05) from d 42 to 91, but did not differ between TM and Control (P ≥ .05). A similar (P ≥ .05) percentage of TM (51%) and Control (49%) bulls passed their BSE 91 d post-treatment. A supplemental trace mineral injection is successful at raising circulating trace mineral levels, but does not alter semen trace mineral levels nor improve semen quality.
Keywords:
Bull, trace mineral, semen