Effect of a Trace Mineral Injection on Performance and Trace Mineral Status of Beef Cows and Calves

Simple Summary Often the forage alone does not provide enough trace minerals to meet the needs of grazing cows and their calves, specifically copper and zinc are almost always deficient, with Se varying among geographical locations. The trace mineral status of cows can affect their ability to get and stay pregnant as well as the health of their calf in early life. Injectable trace minerals can provide additional supplemental trace minerals and allow for a known amount of trace minerals to be delivered to each animal. The objective of this trial was to determine the effects of a trace mineral injection on the trace mineral status of cows and calves and the resulting impacts on the reproductive performance of the cows and the growth of their nursing calves. In this study, use of an injectable trace mineral increased the cow's trace mineral stores, but the non-injected cows had adequate copper and zinc status due to free-choice mineral consumption, and no performance benefits of an injectable trace mineral were observed. The objective was to determine the effects of an injectable trace mineral (TMI; Multimin 90) containing copper (Cu), manganese (Mn), selenium (Se), and zinc (Zn) on trace mineral status and the resulting impacts on reproduction of beef cows and the growth of their calves. Beef cows (n = 200) were assigned to receive TMI or no injection (CON) prior to calving and breeding over two consecutive years. Calves born to cows receiving TMI also received TMI at birth in both years and at 49 +/- 1.3 days of age in year 1. The TMI increased (p = 0.01) liver Zn and tended (p = 0.06) to increase liver Cu concentrations. Short-lived effects of TMI on Se were observed. Liver Cu and Zn would have been considered adequate and Se marginal in the CON. Pregnancy due to artificial insemination and overall pregnancy rate did not differ (p >= 0.36) between treatments. Use of TMI did not increase calf pre-weaning gain. These data indicate that TMI does not improve the reproductive performance of beef cows with adequate trace mineral status or the pre-weaning performance of their calves.