Trace Minerals in cattle - Solutions for supplementation and impact on performance.

By Dr Tim Potter BVetMed PhD MRCVS, senior clinical director Westpoint Farm Vets part of VetPartners

For animals to reach their full production potential and avoid ill health, it is important that their diet provides the right combination of energy, protein and fibre whilst being balanced for the full range of minerals.

Whilst trace elements are only required in very small amounts it is worth remembering that their impacts can be significant. There are more than 15 different elements required in varying quantities for optimum health and productivity and it is beyond the scope of this article to provide a detailed overview of each and every one instead we will concentrate on some of the key trace minerals.

Selenium

Whilst the most commonly identified presentation of clinical selenium deficiency is white muscle disease, ill thrift, reduced immunity and infertility may also be seen. Selenium is important for immune function and to protect tissues against oxidation and the breakdown of cell membranes associated with oxidative stress. During normal oxygen metabolism by-products called free radicals are produced. Free radicals damage cells. Antioxidant enzymes are required to neutralise these free radicals, but unless there are sufficient available trace minerals to produce these antioxidant enzymes, then oxidative stress results, impacting the health and performance of cattle.

Copper

Copper is involved in multiple functions such as energy metabolism, coat pigmentation, immunity, iron metabolism, bone growth and development. Given copper’s large number of different roles, signs of deficiency can be highly variable. Perhaps most recognised are coat colour changes (especially around the eyes and ears), ill thrift, anaemia and potentially infertility. In youngstock copper deficiency can result in signs of lameness and poor growth. It is important that before undertaking copper supplementation the true status of the farm and the animals is established, as over provision can lead to toxicity.

Zinc

Zinc is involved in several different biochemical processes within the body and is a component of several key enzymes. Deficiency signs include poor growth rates, altered gait and stiff joints, failure of wound healing, and reduced reproductive performance

Manganese

Manganese functions in the body by regulating the activity of certain enzymes. Deficiency gives rise to poor growth rates, impaired skeletal development stiff gaits and swollen joints. In severe cases manganese deficiency can also result in calf deformities.

Solutions for supplementation:

Understanding the mineral status of your herd is key and your vet will be able to advise on appropriate testing to establish this. Once you know your status you can then look at how best to address any deficiencies. The most important thing to consider before feeding/administering mineral supplements is the mineral contribution of all inputs already in the animal’s diet. The level of mineral supplementation required by an animal will depend on its stage in the production cycle, but also the forage composition of the diet and the availability of minerals from the raw constituents.

One of the most used ways of providing mineral supplementation is the provision of free choice minerals in the form of licks or blocks. The difficulty with such an approach is the variability in dosing that results; with some animals getting little or none of the supplement whilst others may intake much more than is required.

Providing mineral supplementation in-feed can be an easy way to address the mineral needs of cattle. Animals are more likely to get the required amounts than from licks or blocks, but it is worthwhile remembering that when feed intakes drop either because of disease or around events such as calving, intakes of essential minerals will also fall. Infeed administration is also not appropriate all the time and e.g. whilst animals are at pasture and can be challenging when animals are transitioning between different diets (e.g. at weaning).

Direct administration of the required minerals to animals via injections, oral drenches or ruminal boluses has the advantage of ensuring that each animal receives the prescribed dose of minerals and trace elements and administration can be targeted to coincide with specific risk periods. It is often viewed as more labour intensive, requiring handlings etc but the benefits of improved performance and reduced disease can mean the payback is worth it.

When considering mineral supplementation it is important to also understand that other minerals such as sulphur, molybdenum, iron and calcium which are present in feed, forage and water can act as antagonists and limit the absorption of trace minerals administered orally. These minerals interact with trace minerals in the rumen reducing their absorption and meaning only a small proportion of the supplement administered is ever available to the animal. The only way to avoid this interaction is administer trace minerals via the injectable route.

Targeting at risk times

When considering the production cycle of cattle there are key phases when animals are most likely to see the impact of clinical and sub clinical mineral deficiencies. For adult animals these are generally around breeding and calving. For youngstock proper mineral nutrition is essential throughout the growing period if they are to achieve their targeted growth rates but stressful events such as weaning and other management changes can also increase the risk of mineral deficiencies.

Knowing there are specific risk periods allows us to be very targeted with additional supplementation. In dairy cattle, studies have demonstrated that cows treated with the injectable mineral supplement Multimin at dry-off, 30 days pre-calving and 35 days in milk showed improved milk quality and udder health and reduced mastitis rates.

In beef cattle treated with the same product prior to calving and then again 30 days prior to the start of the breeding period, a much more compact calving pattern was achieved. In younger growing animals targeting mineral supplementation around stressful events such a movements and weaning can have significant effects. Several calf rearing units I work with have started using Multimin prior to major management changes and have seen reductions in disease incidence and reduced need for antimicrobial treatments.