Source: Beef Cattle Research Council, www.BeefResearch.ca
What mineral supplementation do I need and when do I need it?
Beef producers might know they should supplement their herds with mineral, but trying to wade through all the choices at the livestock supply store can be overwhelming. Commercial suppliers seem to make claims and offer something different, but with tubs and bags of every colour and price available, how to you know which one is right for your herd? What minerals do your cattle actually need and how is it best delivered?
Megan Van Schaik, a Beef Cattle Specialist with the Ontario Ministry of Agriculture, Food and Rural Affairs (OMAFRA) says there are some key things producers want to look at. In general, producers should be supplementing mineral to their herds whether they are grazing or being fed a winter ration.
Van Schaik says there are a host of variables that impact mineral nutrition and deficiencies in beef herds. “They present in many different ways and alarm bells usually go off when we see reproductive issues,” she says, but adds that mineral status can be linked to general health problems and even calf abnormalities. Mineral deficiencies can also cause less obvious production losses that can be easily avoided with proper supplementation.
A new collaborative project is getting underway between the drought, with collaboration from OMAFRA and the University of Guelph, to track and monitor the mineral status of a sample of beef cattle herds in that province. A similar project tracked trace mineral status of herds across Alberta, Saskatchewan and Manitoba and identified some key gaps, noting that up to 43% of cows sampled were deficient in copper.
Why do cattle need mineral supplementation?
Beef cattle rely on at least seventeen minerals which are categorized as macrominerals and microminerals (also known as trace minerals).
Macrominerals include calcium (Ca), magnesium (Mg), phosphorus (P), potassium (K), sodium (Na), chlorine (Cl) and sulphur (S) and are needed in relatively large quantities of more than 100 parts per million (ppm). Macromineral requirements are usually expressed on a percent dry matter (% DM) basis in an animal’s ration.
Beef cattle also need ten microminerals, also referred to as trace minerals, which include chromium (Cr), cobalt (Co), copper (Cu), iodine (I), iron (Fe), manganese (Mn), selenium (Se) and zinc (Zn). These are needed in small quantities, and as such are often expressed on labels as ppm (parts per million), or mg/kg.
Minerals are required for several functions including skeletal development, immunity, production, nervous system maintenance and overall metabolism. Perhaps even more importantly, minerals interact with other minerals, vitamins and water or feed sources. This can limit absorption or availability.
The concentration of minerals in forages and feeds varies depending on soil, plant and management factors. While spring pasture growth looks lush, the reality is that few pastures — regardless of plant species — fully meet the mineral requirements of a lactating cow. Both macrominerals, such as calcium, phosphorus and magnesium, and trace minerals, such as copper and zinc, are in short supply in tame and native pastures and therefore require supplementation.
Also, as a cow goes through gestation, calving and then attempts to breed back, her mineral requirements fluctuate. Supplementation is necessary to keep her on track.
Drought conditions and water quality can complicate mineral nutrition, and different anti-quality factors will impact certain minerals and their absorption. “The only real way to find if you have mineral deficiencies and antagonistic factors is to test feeds and water,” explains Van Schaik.
Include mineral analysis of forages and feed ingredients as part of regular feed testing. Testing for calcium and phosphorus will show the ratio present in the feed. The ratio of calcium to phosphorus in a diet should be between 2:1 and 6:1. Analysing magnesium, potassium and calcium in feeds is important to ensure the ratio of potassium relative to calcium and magnesium combined is below 2.2, which will prevent tetany.
Feed testing is particularly important when producers may be feeding alternative feeds such as drought-stressed crops or canola forage, or when cattle may be drinking stock water that is high in Total Dissolved Solids (TDS). For example, copper deficiency is a standard concern for many areas of Canada but in a drought situation, elevated sulfate levels in stock water can make a bad problem worse by tying up available copper. This can lead to a reproductive wreck which could be prevented with mineral supplementation containing appropriate levels of copper.
Too much sulphur can also cause sulphur toxicity and should be analysed in both water and feed samples. Cumulative sulphur levels from water and feed should be less than between 0.3 and 0.4 percent to prevent toxicity which can result in polioencephalomalacia.
Molybdenum also ties up copper, so testing forages for molybdenum will help producers understand of they have higher levels and are at risk for copper deficiency.
Not all supplements are created equal
Van Schaik says it’s important for producers to note that minerals come in different forms and modes of action which impacts the “bioavailability” of that mineral, which is the animal’s ability to absorb it. “There’s value in assessing whether your mineral requirements benefit from enhanced bioavailability,” she says, particularly for a trace mineral deficiency like copper.
Minerals come in two main forms, inorganic or organic (i.e., chelated) forms. Most supplements are a combination of inorganic and organic forms and are priced accordingly. Inorganic mineral supplements are the most affordable, however they are typically the least absorptive and can even break down in a feeder before they are consumed. Organic, or chelated, minerals are bound to proteins, organic acids or yeasts. Supplements containing organic minerals are more expensive however they are much more effective, particularly if producers are looking to quickly eliminate a deficiency during periods of stress.
In spite of whatever claim commercial mineral suppliers make, there is no one product that will meet the need of every farm or herd. Mineral needs change by season (i.e., grazing compared to winter feeding) and whether cattle are growing or finishing or what stage of gestation or lactation they are at.
Producers who work with a nutritionist may choose to create a custom blend designed to address specific deficiencies as identified by water and feed analyses. Veterinarians can analyse blood or liver samples from a herd to determine a farm’s unique mineral needs. “A blood sample can be used as a snapshot to see if there are any deficiencies,” Van Schaik says, but adds that some deficiencies are best detected through liver biopsies since those samples tell you the most about stored trace mineral levels.
Methods of supplementation
Mineral can be delivered through a complete diet where minerals are part of a total mixed ration (TMR), or they can be offered in block form, lick tubs or loose mineral. Some products also contain protein and energy supplements, which will affect intake.
Offering mineral as part of a complete feed delivered in a feed bunk is ideal because it allows for more controlled consumption. Data shows that cows fed trace minerals in a ration were six times less likely to be copper deficient at calving and experienced less delay coming back into heat compared to their counterparts fed trace minerals free-choice. This method requires management, however. “Pay attention to things like consistent intake across the herd, ensuring adequate bunk space for cows. In any supplementation scenario, it’s important to pay attention to other factors to prevent exposure of mineral to the elements like rain or wind,” explains Van Schaik.
Not every production system is suited to daily mineral supplementation, however, and many herds spend the majority of their time out grazing. While a general rule of thumb is that forage-based diets benefit from a 1:1 calcium-to-phosphorus ratio supplement, and grain-based rations (including greenfeed) benefit from 2:1 or even 3:1 calcium-to-phosphorus supplement, the best way to determine that is to do a mineral profile on your pasture.
Salt can be mixed in with loose mineral supplements to increase or limit the amount of intake. Because cattle crave salt, it can be a useful additive to encourage cattle to consume the required amount of mineral, however there are limits to how much salt they will eat, which also prevents overconsumption. Van Schaik cautions producers when it comes to offering both loose mineral and salt separately and side by side, however. “There is a higher risk of reducing mineral intake if the salt is provided separately beside the mineral,” she explains.
Van Schaik adds that mineral placement in pastures is key. “If you’re grazing cattle, you want to have your mineral supplementation in close proximity to where cattle are gathering,” she says. “Water is a good place to offer mineral supplementation,” Van Schaik explains, and adds you want to put your mineral in a feeder so that it is protected from the elements. Producers have created some unique portable mineral feeders that move along with cattle in rotational grazing set-ups. Depending on the design of the mineral feeder, a general rule of thumb is having one mineral feeder placed for every 30 to 40 head.
Read the label and do the math
“It’s really important to make sure producers are reading label instructions for adequate intake,” says Van Schaik. “The label will typically provide intake on a per head per day basis – that’s a big thing. It can be tempting to add a bag of mineral to a feeder and walk away, but routine monitoring of mineral intake is really important,” she adds.
As well, the label will indicate how much of which type of mineral is found in the product. Trace mineral intake levels are usually described in parts per million (ppm) or milligrams per kilogram (mg/kg). Whether a commercial product meets the mineral needs of an animal depends on how much is in the product and how much the animal needs to consume. As an example, a producer might review the labels of two mineral supplements: one contains 1,500 mg/kg of copper and the other contains 3,000 mg/kg of copper. If the label indicated animals are expected to consume 80 grams of mineral per day of the first supplement, that product will provide 120 mg of copper (1,500mg/kg x 0.08 kg). The second product label indicates that intake should be 90 grams per day, which would mean the second supplement provides 270 mg of copper.
Mineral supplements are an effective way to ensure beef cattle are meeting their requirements and optimizing production, whether they are grazing or being fed a total mixed ration. Paying attention to labels, the type and bioavailability of the product, being aware of potential antagonistic factors and monitoring intake will ensure producers provide adequate and effective macro and microminerals for their herd.