THE FLORIDA CATTLEMAN AND LIVESTOCK JOURNAL
The effect of injectable trace minerals on antibody responses to vaccination in beef calves
Grazing cattle have a specific nutritional requirement for trace minerals. These elements are known to support physiological functions related to growth, reproduction, and immunity in livestock. Forage is the primary source of trace minerals for grazing cattle with secondary sources being water and ingested soil. In almost all cases, these sources of trace minerals will not fully supply the requirements of grazing cattle resulting in a deficiency in one or more of the trace mineral nutrients. Understanding the specific deficiency and devising a management plan for successful supplementation is the key to optimizing trace mineral nutrition and thus overall cattle performance.
Supplementation of trace minerals may occur through a variety of means, including free-choice loose mineral mixes, trace mineral blocks, and fortified energy/protein supplements. In the past couple years, we have received numerous inquiries regarding the use of injectable trace minerals in Florida cow/calf production systems. Injectable trace minerals have been available for many years, but the technology, targeted application, and scientific assessment of efficacy has more recently been a subject of attention among cattle producers, veterinarians, and researchers.
The technology associated with trace mineral injections has evolved considerably in the past several years. Most cattle producers and veterinarians associate trace mineral injections with two product formulations that were common during the 1970’s and 80’s. These products were, 1) combined formulation containing selenium and vitamin E, and 2) copper glycinate. These products, particularly copper glycinate, were notable and widely recognized for producing injection-site reactions. For this reason, only minimal application of these products was witnessed throughout the industry. More recently, other formulations of trace mineral injections have become available with minimal or no injection-site reactions. In addition, some of these products provide several elements in a single injection, namely copper, zinc, selenium, and manganese.
Over the past year, we have investigated one of the commercially-available, injectable trace mineral products (MultiMin 90; Fort Collins, CO). Our interest in the product originated from research findings from colleagues at other Universities which suggested improved growth performance, feed efficiency, and decreased illness in stressed feeder calves. Our specific aim in these current studies was to assess measures of mineral status, performance, and immune competence in beef calves receiving MultiMin or a Control injection of sterile saline.
One of the studies was conducted in collaboration with individuals from Iowa. In that study, a single injection of MultiMin or sterile saline (Control) was administered to weaned steer calves concurrently with a single dose of a commercially-available modified live vaccine. As a response variable, we measured the amount of antibody produced as a result of vaccination. On the day of vaccination and MultiMin treatment, serum concentrations of copper, zinc, manganese, and selenium were similar among all steers and all values were within the sufficient range for cattle, suggesting that there were no pre-existing mineral deficiencies among the group of steers utilized in this study. By day 14 after treatment administration, steers receiving the saline control treatment experienced a decrease in serum zinc and selenium concentrations and on that sampling day were lower than steers receiving MultiMin. Neutralizing antibody concentrations to bovine viral diarrhea (BVD-1 and 2) and bovine herpes virus (BHV-1; primary causative pathogen for infectious bovine rhinotracheitis - IBR) increased in all steers following vaccination. Antibody titers against BHV-1 were greatest for steers receiving MultiMin vs. Control on day 14, 30, and 60 post-vaccination (Figure 1A).
In a second evaluation, conducted at Ona, FL, 34 yearling heifers were randomly assigned to receive 4 injections of MultiMin or sterile saline (Control) at a ½ recommended dosage (1 mL/200 lb body weight) on days 0, 51, 83, and 127. The heifers grazed winter, stockpiled limpograss pastures and were provided free-choice, stock salt with no added trace minerals. On day 51, at the time of the second injection, all heifers were challenged with a 10-mL injection of a 25% porcine red blood cell solution as a novel pathogen exposure. The production of antibodies against the porcine red blood cells was found to be greatest for heifers receiving MultiMin, compared to Control (Figure 1B). On day 186 (59 days after the final treatment administration) liver biopsy samples were collected from all heifers to determine trace mineral status. Over the 186 day evaluation, heifers receiving MultiMin had a 21% greater average daily gain compared to Control heifers (0.69 vs. 0.57 lb/d). In addition, by the end of the evaluation, heifers receiving MultiMin had greater liver concentrations of copper and selenium compared to control heifers; however, liver concentrations of all minerals, irrespective of treatment, were within the adequate range for beef cattle.
Collectively, these findings suggest that the trace mineral status of beef calves can be increased by the administration of injectable trace minerals. Additionally, antibody production to vaccine appears to be heightened in calves receiving injectable trace minerals. These responses are appearing to be evident even in calves exhibiting adequate trace mineral status. It is unclear, therefore, if these observed increases in antibody titers are a response to increased trace mineral status or a priming response to the immune system. Nonetheless, this heightened immune response may be an important contributing factor to the improved measures of health and performance reported by other investigators in previous studies.
In summary, it is important to note that trace mineral injections are not to be used as sole replacements for more traditional nutritional-sources of minerals, but as a complement to a properly formulated, free-choice, salt-based trace mineral supplementation program. In most cattle production environments, there is a need for supplemental macro-minerals, such as salt, phosphorus, potassium, and magnesium. Consideration toward meeting the animal’s requirement of these nutrients is also important and should be considered when reviewing the advantages and benefits of incorporating trace mineral injections into a specific cattle production system. In some circumstances, particularly with stressed calves or growing animals, the use of injectable trace minerals may improve performance and immune competence. Also, production systems that have difficulty with voluntary consumption of free-choice mineral or struggle with the presence of mineral antagonists (i.e. sulfur and molybdenum), may find benefit from the inclusion of injectable trace minerals in their cowherd management system. Note: The asterisks on Figures 1A and 1B denote statistical differences among treatments within sampling days.