Trace minerals — including copper, selenium, zinc, manganese and cobalt — are needed in vanishingly small amounts. However, when these nutrients fall even the smallest bit short of a cow’s needs, the consequences can be significant. These results can include slower growth, compromised immunity and poor reproduction.
Although trace minerals make up less than 0.01% of an animal’s body weight, they’re fundamental co-factors in enzymes, antioxidants, metabolic and immune pathways. Subclinical deficiencies may be a more extensive problem as the symptoms are not evident and there is no intervention, leading to economic losses.
David Schaeffer, professor at the University of Illinois, and his colleagues recently published work analyzing trace mineral concentrations from beef and dairy livers submitted to the California Animal Health & Food Safety Lab System laboratory between 2012 and 2021. The aim of this work was to compare any correlation patterns of copper, selenium, and manganese contents, and incidence of disease.
This work included 1,495 liver samples collected from cattle submitted for diagnostic testing. They were categorized as beef (857) or dairy (638), and further grouped by age (neonates, adolescents and adults).
The study revealed significant differences between deficiencies in beef and cattle. Overall, 73% of beef cattle and 45% of dairy cattle were found to be deficient in at least one trace mineral. In beef cattle, 46% of cattle were deficient in selenium, while 39% were deficient in manganese and 33% were deficient in copper. In dairy cattle, 10% of cattle were deficient in selenium, while 37% were deficient in manganese, and only 5% were deficient in copper.
The observed increased incidence of deficiency in beef cattle is likely expected as these animals often rely on free choice minerals, while dairy cattle are fed a total mixed ration including a mineral supplement. Interestingly, Schaeffer also reported a large portion of dairy cattle may have been oversupplemented as they observed above normal copper and selenium levels.
Associations between mineral status and disease occurred across both groups, but were most prevalent in beef cattle.
In beef cattle reported to have bovine respiratory disease (BRD), 68% of animals were deficient in copper, selenium or both minerals. The median age of these animals was 8 months, and most of them had been recently transported and co-mingled with other calves.
One thing the authors noticed was some conditions that are usually subclinical in beef cattle, for example parasites, were fatal in animals that were deficient in copper, selenium, or both.
“Now obviously we don’t know the condition score of those animals,” says co-author David Villar on a recent episode of “Have You Herd?”. “I would imagine it was pretty poor to die from internal parasites.”
As stated above, dairy cattle cases had much lower prevalences of trace mineral deficiency. Along with this, they also had lower incidences of correlation between deficiency and disease.
Of the dairy cattle with only one deficiency, the most frequent diagnoses were BRD (23%), Salmonella (14%), scours (16%), and septicemia (6%). Of all dairy cattle, 11% of those with BRD also had a copper or selenium deficiency.
It’s important to remember these are correlations between mineral status and disease, not causation.
Villar highlights what he hopes producers and veterinarians would take away from this work: “The main conclusion I would make is that beef, but not dairy, are still largely deficient in essential microminerals, copper and selenium. We need to check the herd management to see what’s happening.”
These results present an opportunity for producers and veterinarians to build preventative mineral nutrition programs, especially in beef herds where deficiencies are more prevalent. Proactive monitoring and targeted supplementation could reduce disease, mortality and economic loss in cattle herds.
