Article

The importance of trace elements for calves at grass

It is a well-known phenomenon that nutrition will impact the health and immune function of young calves as well as adult cattle.

Mineral and vitamin deficiencies, or indeed too much of a good thing can alter various components of the immune system. The later effects of mineral deficiencies usually show in the form of ill thrift because of a weakened immune system. If these animals are challenged by disease or artificially via vaccination they will have a poorer response. Ultimately, they are also more vulnerable to common youngstock issues such as diarrhoea, pneumonias etc.

Generally, mineral deficiency isn’t an issue in pre-weaned calves as all the necessary minerals and vitamins are supplied in their milk feed. However, as calves are turned out to grass post-weaning, they can be more susceptible to deficiencies.

Grass will usually supply a certain amount of what the calf needs, however this usually won’t be adequate in terms of trace elements.

Grass analysis

Uniblock previously analysed grass samples periodically across Irish farmland. During the mid-late Spring months, a reduction in cobalt, selenium, copper and zinc was observed when compared to earlier samples taken in February. Recent published findings highlighted when zinc and selenium were supplemented during the transition period from liquid to solid diet (weaning) in calves it proved advantageous to their overall health and growth performance (Volpato et al., 2018).

Sufficient trace element supplementation is fundamental to supporting an optimal mineral status, especially during episodes of stress.

Consequences of mineral deficiency

Zinc, copper, and selenium are largely associated with immune function in calves. Inadequate zinc levels have been previously associated with poor growth and diarrhoea in calves (En-Jalbert et al., 2006). Zinc plays a major role in both disease resistance and immune responsiveness. Lack of zinc in the diet can also have a detrimental effect on skin health, skin is a very important organ as it acts as the first line of defence against disease.

Calves with a severe zinc deficiency are lethargic; their wounds heal very slowly, if at all; and they are highly vulnerable to nonspecific secondary infections, which can often result in death. If a calf is zinc deprived, they will grow at a slower rate because of consuming less food (Miller et al., 1965). Even when intakes are the same as non-deficient calves they won’t grow as well. This is a consequence of deficient animals being less efficient at utilising the digested nutrients. 

Enhanced growth and reduction in the incidence of pneumonia and diarrhoea was reduced and signs of immune competence were improved when zinc was added to Holstein calves diet (Abdollahi et al., 2019).

Deficiencies in selenium and copper levels are associated with reduced antibody production and responses to infections. Therefore, these trace elements are very valuable to the calf around the transition period as they are more vulnerable to disease at this stressful time. Copper deficiency can occur in fast growing calves over 6 months. A lack of copper in the diet can present calves with issues such as poor growth rates, bone fractures, and loss of coordination.

Often copper deficiency is an issue in adult cattle and quite often is a result of antagonists such as sulphur, molybdenum, or iron. These antagonists can lock up the copper, making it somewhat unavailable to the animal. However, because young calves do not have a fully functional rumen, they do not have the copper blocking effects from the antagonists like sulphur and molybdenum in the rumen compared to adult cattle. Consequently, copper is much more available to be absorbed in the calf’s gut. It is important to have a look at the different feed sources young calves are consuming and avoid over supplementing to cause a toxicity. Copper intoxication can sometimes lead to death or if they survive it can have a negative effect on their overall productive and reproductive life.

Selenium acts as a natural antioxidant, it supports immune response and function and is closely linked to Vitamin E.

How supplementation helps

Studies have been conducted on the supplementation of selenium to weaned calves, these calves had reduced mortality to bovine respiratory disease (BRD) and greater growth rates compared to calves that weren’t supplemented. Often calves can exhibit poor growth performance, low immunity, increased respiratory rates, and greater susceptibility to diseases attributable to reduced feed intake during the summer months.

Correct supplementation of trace minerals to calves at grass can have a positive effect on several productive measures such as how they respond to vaccination (Arthington and Havenga, 2012), their feed efficiency (Clark et al., 2006), less treatments for sickness (Berry et al., 2000), and less morbidity treatment costs overall (Richeson and Kegley, 2011). All these benefits by far outweigh the cost of providing calves with the correct minerals and vitamins whilst at grass.

Leave a Reply

Your email address will not be published. Required fields are marked *