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Trace mineral deficiencies can lead to production declines, animal health events and reproductive wrecks.
How can I best meet the mineral requirements of my beef herd? It comes as no surprise that the answer to this question is not a simple one. There are many factors impacting the mineral requirements of beef cattle such as stage of production, age and body condition. These are further compounded by the bioavailability of the mineral source provided and any antagonists that may be present in the diet.
Regional variations in the trace mineral content of forages and soils create high risk areas where trace mineral deficiencies are more likely to occur. Supplemental sources need to be provided to prevent production declines, animal health events or reproductive wrecks.
Copper deficiency in mature beef cows is an issueacross Canada
Recently published data from work led by Dr. Cheryl Waldner with the Western College of Veterinary Medicine in Saskatoon, SK, showed 64% of mature beef cows in Western Canada and 59% of mature beef cows in Eastern Canada have less than adequate copper status1. This is based on data collected in 2019.
“One of the trends we saw with the copper data was that it looked a bit more regional in the younger cows. But when we looked at the mature cows, the extent of the problem across the country became really apparent,” Dr. Waldner explains. “If you are a cow-calf producer in Canada, you need to worry about copper supplementation in your herd regardless of your location.”
Dr. Van Mitchell and his team at Metzger Veterinary Services in Ontario performed trace mineral screening tests in 2023 on calves coming into Ontario feedlots. They found that 56% of calves sourced from Western Canada (Manitoba, Saskatchewan and Alberta) were marginal or deficient in copper. This is compared to 33% of Ontario calves falling in the same category.
“Generally, for copper deficient cattle, we attribute this to poor forage quality, little to no mineral intake or high sulfate or molybdenum in the diet,” he explains.
Dr. Andrew Acton with Deep South Animal Clinic in Ogema, SK, says copper deficiency is the most common one he has observed through his practice and notes it can also be one of the hardest to correct.
“Everything is an interrelation between copper, molybdenum and sulfur. An imbalance in one can cause problems with the others,” he explains.
The research from Dr. Waldner’s group also evaluated molybdenum levels in beef cows and found significant regional variation. Molybdenum is found in soils and in plants, and it can tie up copper. This means if molybdenum is present in the forage, any copper that is also there is no longer available for use by the animal. This results in secondary copper deficiency.
“If you are a cow-calf producer in Canada, you need to worry about copper supplementation in your herd regardless of your location.”
– Dr. Cheryl Waldner, Western College of Veterinary Medicine
A primary mineral deficiency occurs when cattle are consuming a diet devoid of that mineral.
A secondary mineral deficiency occurs when cattle are consuming enough of a specific mineral to meet requirements, but mineral antagonists are present in the diet which interfere with the normal absorption of that mineral.
In addition to molybdenum, high sulphate levels present in water sources or in some alternative feeds, can further limit the bioavailability of copper in the diet. Therefore, despite supplementation, many herds may still be deficient.
Selenium status is a regional concern
When it comes to selenium, 73% of cows in Eastern Canada and 33% of cows in Western Canada have serum selenium levels of 0.8 ppm or less, which is considered less than adequate.
“There are a few smaller areas across Western Canada where we see a problem, basically west of Highway 2 in Alberta and into BC. But the big thing that came out of those maps is how much more common selenium deficiency is in Eastern Canada,” Dr. Waldner explains, adding that for producers in Ontario, Quebec and the Maritimes, the increased regional risk of low selenium needs to be considered when evaluating a mineral supplementation program.
“It is a soil-derived issue,” says Dr. Mitchell, “and it is definitely the largest problem we see (in terms of mineral deficiency) in Ontario-sourced calves. It is a big contributor to bad calf scours outbreaks, calves that are weak born and poor immune responses.”
In addition, most forages and crops grown in Ontario are deficient in selenium, meaning that without supplementation, cattle are not receiving adequate amounts from their diet.
“Our area [south-central Saskatchewan] is not typically deficient in selenium, and we are a little more likely to see selenium in excess in some herds,” Dr. Acton notes. “When we do see issues, it is likely related to drought conditions and certain plants being consumed.”
Selenium responds predictably with supplementation, in that body levels go up relatively quickly when supplementation is provided. However, producers need to ensure that intakes are adequate and the right level of trace minerals are formulated into the product.
“If producers get a load of mineral that is not designed for a selenium deficient area, there is not enough selenium in there. Even if cows consume adequate amounts based on the label, it’s still not enough,” Dr. Mitchell cautions.
Consequences of a trace mineral deficiency
Trace mineral deficiencies can take months to manifest into clinical symptoms, depending on factors such as diet, water quality or health status, says Dr. Acton. Symptoms observed are often not unique to any specific deficiency and can include low conception rates, late-term abortions, poor-performing cattle despite high-quality feed, reduced immune response or rough hair coats.
Many trace minerals, such as copper and zinc, are essential for pregnancy, and when cow requirements are not met, they are at an increased risk of being open in the fall.
Both Dr. Acton and Dr. Mitchell stress that supplementation during gestation is one key timeframe which impacts both calf and cow health and production as well as the cows future reproductive performance.
“During gestation, the cow will sacrifice some of her own body stores of trace minerals for the fetus, and, in some cases, the calf will be born with adequate levels while the cow is now deficient because of it,” Dr. Acton says.
“When a cow is deficient during gestation, that calf is also born deficient. And when they get a poor start, it’s going to affect them for their entire productive life,” Dr. Mitchell explains. “It is common practice to provide a selenium injection to a calf at birth, but these will often take four to seven days to have a positive effect on a deficiency. So, doing it at birth may be too late in a truly deficient calf; the focus needs to be on the pregnant cow.”
“It is common practice to provide a selenium injection to a calf at birth, but these will often take four to seven days to have a positive effect on a deficiency. So, doing it at birth may be too late in a truly deficient calf; the focus needs to be on the pregnant cow.”
– Dr. Van Mitchell, Metzger Veterinary Services
Good trace mineral nutrition becomes even more important in younger cows. These animals are still growing themselves and must balance what they are putting into their calf while still meeting their own needs.
“Another aspect is the impact of trace minerals on immune system function, both in terms of the risk of animals getting sick and how they are able to respond to the vaccines we are giving them,” Dr. Waldner explains.
“The immune system is very complicated, and we need all aspects of it to be firing,” she says. “There’s evidence to show that trace mineral nutrition is important for both the parts of the immune system that create antibodies to the vaccine and the parts of the immune system that directly impact the cells that are important to the immune system response.”
When cows and calves do not have adequate trace mineral levels, their ability to respond to vaccinations is reduced.
Monitoring a beef herd’s trace mineral status
There are several tests available that can be used in diagnosing trace mineral deficiencies, which include serum samples and liver biopsies. Using these tools in routine testing can help identify potential production-limiting situations, but must be done with a full understanding of the limitations and how to interpret the results.
“In the case of copper, the liver is the gas tank, and the bloodstream is the fuel line. The gas tank supplies the fuel line, so if the fuel line is low, then it means copper levels are very low or close to being deficient,” Dr. Acton explains.
“When we are looking at a herd problem to start with, the serum samples are a nice screening test,” he says. “If we take 10 or 20 samples and we see 30% deficient, we know we have a big problem going on because more of them are probably deficient than that.”
Dr. Waldner adds that “blood tests are quicker, easier and typically cheaper. Due to this, we are more likely to sample more cows from a wide range of management groups than when we sample liver.”
“In the case of copper, the liver is the gas tank, and the bloodstream is the fuel line. The gas tank supplies the fuel line, so if the fuel line is low, then it means copper levels are very low or close to being deficient.”
– Dr. Andrew Acton, Deep South Animal Clinic
She says a lot of producers are using free choice supplementation, which results in a high variation in trace mineral intakes. “When the mineral status of the cow herd is very variable, doing a small number of potentially more sensitive liver tests could miss the extent of the problem.”
Blood sample being collected. Photo credit: Dr. Andrew Acton.
Serum levels of trace minerals will fluctuate depending on the consistency of mineral intake, cautions Dr. Mitchell, adding that a deficient animal might actually show adequate levels with a blood test if the liver has recently mobilized stored levels to compensate for the deficiency.
While blood samples are an excellent first step in monitoring a herd’s mineral status, the use of liver biopsies is recommended when it comes to determining mineral supplementation requirements or if an acute issue is observed within the herd.
“To know how much to supplement, the liver stores need to be known, which is where liver biopsies come into play. They allow for the precise measurement of essential nutrient levels and detection of deficiencies or toxicities that are not easily identified through external signs or routine blood tests,” Dr. Waldner says.
When to test for trace mineral status
When clinical signs are presented, or a herd is experiencing less than optimal production performance, liver or blood samples are recommended by all experts as part of the diagnoses process. The results can also highlight potential nutritional issues for a given feeding period.
Evaluating the trace mineral status of a beef herd at fall pregnancy checking should allow ample time to adjust supplementation to correct any identified deficiencies prior to calving.
“If we are seeing issues with weak born or stillborn calves, this gives an indication that the issue is with winter feeding. If calves are born healthy, bright and alert, but after weaning get sick and we have high pull rates, now we are looking at summer nutrition,” advises Dr. Mitchell.
Some producers may want to evaluate the trace mineral status of their herds routinely to ensure formulated rations are meeting requirements.
Dr. Waldner and Dr. Acton suggest that monitoring trace mineral status at fall pregnancy checking is ideal. Testing at this point should allow ample time to adjust supplementation to correct any identified deficiencies prior to calving.
Work with your veterinarian and nutritionist to ensure the trace mineral requirements of your herd are being met.
References
1 Waldner, C., McLeod, L., Parker, S., and Campbell, J. 2023. Update on copper and selenium in Canadian cow-calf herds: regional differences and estimation of serum reference values. Translational Animal Science, 7(1). Available at: https://doi.org/10.1093/tas/txad062
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