Oorsig/Review
Trace Mineral Nutrition of Beef Cattle
Application of Injectable Trace Minerals
John Arthington
Professor and Center Director, University of Florida
Cattle have a specific nutritional requirement
for trace minerals. These elements are known
to support physiological functions related to
growth, reproduction, and immunity. For grazing
cattle, forage is the primary source of trace
minerals with secondary sources being water and
ingested soil. In almost all cases, these sources
will not fully supply the requirements of grazing
cattle, resulting in a deficiency in one or more
trace minerals. Trace mineral antagonists, such
as sulphur, molybdenum, and iron can further
complicate deficiencies. 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-
fortified blocks, and fortified energy/protein
supplements. The most common delivery method
for supplemental trace minerals to grazing beef
cows is through a free-choice salt lick. Cattle
have a nutritional need for sodium and chlorine.
This requirement has been realized for centuries
due to a natural craving for common salt. In
fact, salt is the only nutrient that cattle display
a nutritional wisdom for consumption. When
supplemental salt is available, sodium deficiency
will not occur. This nutritional wisdom does not
apply for essential trace minerals, therefore, beef
producers often utilize salt as a carrier to deliver
other supplemental trace minerals to grazing
cattle. The major problem with this management
technique is the normal, and sometimes dramatic,
seasonal fluctuations in intake of salt-based
supplements (Arthington and Swenson, 2004).
These fluctuations are due to changes in salt-
craving by grazing cattle, often due to increased
dry matter of forages and in some cases, increased
sodium content of drinking water.
Injectable trace minerals (ITM) is another
method of supplementation. 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. An
4
advantage of ITM, compared with traditional
oral supplementation methods, is the targeted
delivery of a known amount of trace minerals to
individual animals. This removes the variability
associated with annual fluctuations in voluntary
intake of free-choice salt-based supplements.
In addition, ITM can be used within production
environments that might experience difficulty
managing the routine delivery of free-choice
mineral mixes, such as extensive rangeland
systems, seasonal grazing of mountain meadows,
and seasonally flooded pastures. Further, the
contribution of wildlife to the overall consumption
and disappearance of free-choice mineral mixes
can cause complications and add further value to
the use of ITM. Our interest in ITM investigation
originated from research findings of colleagues
at other Universities which reported increased
mineral status (Pogge et al., 2012) with increased
feed efficiency (Clark et al., 2006), reduced
treatments for illness (Berry et al., 2000), and
reduced morbidity treatment costs (Richeson et
al., 2009) in stressed feeder calves. Our specific
research aim was to assess measures of mineral
status, performance, and immune competence
in beef calves receiving ITM. Collectively, our
findings suggest that the trace mineral status of
cattle can be increased by the administration of
ITM. Additionally, antibody production to vaccine
appears to be heightened in calves receiving
injectable trace minerals. These responses appear
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.
Prof Arthington will be one of the speakers at
the upcoming 2019 Congress of the Ruminant
Veterinary Association of South Africa
(20 - 22 May, Coastlands Hotel, Umhlanga).
Three presentations will be offered that focus
on the effective use of ITM in grazing beef
cattle production systems.