Winter Minerals and Supplements for Beef Cattle.

 By Heather Smith Thomas.

In many parts of the country winter means feeding cows.  Pastures are often mature and dry (short on protein) or covered with snow, necessitating some kind of feed and/or supplement program.  When feeding hay, it is important to make sure it has enough quality to supply the necessary nutrients, which include protein and minerals.  If levels of key nutrients are short, these must be provided in a supplement. When winter grazing involves mature, dry pastures, supplementation is often needed.

Mineral Supplementation
Sodium, chlorine and potassium are crucial to maintain fluid balances in the body and blood.  Iron is an important component of red blood cells—enabling them to carry oxygen.  Bone formation and milk production depend on calcium and phosphorus.  Calcium and phosphorus are called macro-nutrients because they are required in fairly large amounts compared to the trace minerals (copper, iron, iodine, manganese, selenium and zinc), which are needed in very tiny amounts. Trace minerals are very important to health, however.

Adequate levels of copper, zinc, manganese and selenium are crucial for a healthy immune system and reproduction.

Most producers use supplemental minerals to augment cattle diets--often supplied in salt/mineral mixes provided free choice.  Consumption is varied however, with some animals consuming too much while others eat inadequate amounts or none at all.  Other aspects of diet (certain minerals that bind with the supplemented mineral) may hinder absorption by the body.  Some stockmen individually dose their animals by drench, bolus or injection—to make sure they directly receive the necessary minerals.

Dr. Lourens Havenga, CEO of Multimin USA, Inc. started several research projects on trace minerals in 2009.  There have also been university studies assessing how rapidly injected trace minerals are absorbed and how long they are stored in the liver.  Other studies have evaluated performance of shipping-stressed cattle receiving injected minerals versus cattle that did not, effects on calf health and reproductive performance when injecting cows before and after calving, and how trace mineral status affects respiratory risk and finishing performance in beef steers.  

We now know that trace minerals are crucially important in cattle health, from conception through harvest and all along the way in the reproductive life of cows and bulls.  “Deficiency issues in young calves originate during the last 90 days of the cow’s pregnancy.  This is when the fetus is growing fastest and also when most of the trace minerals are being transferred to the calf from the cow (stored in the calf’s liver), for that calf’s early life,” Havenga says.  The main times in a cow’s life that she needs more trace minerals is 30-90 days before calving and 30-60 days before breeding.

Selenium
“The most common mineral deficiency in the U.S. that impacts young calves is selenium.  Inadequate selenium in the cow during her last trimester can cause several problems.  If deficiency is severe, we see white muscle disease in calves.  Muscle tone is poor; they are unable to get up and suckle,” says Havenga.  If deficiency is severe the cow may retained her placenta, which may impact her ability to recover quickly from calving and rebreed on schedule.  

Deficiencies will impair her immune system and she may end up with a low-grade uterine infection and be slower to rebreed.  “Her calf won’t have white muscle disease, but may have a dysfunctional immune system, and be prone to scours or respiratory disease,” he explains. “If the cow is low in selenium she produces fewer antibodies and a lower-quality colostrum,” says Havenga.

Zinc
Research has found that if the cow is low on zinc just prior to calving, she may have a longer-than-normal gestation.  “Signaling of the calf to be born is weaker in that cow.  If she carries the calf longer it may be too big to be born without assistance.  Low zinc in a calf will cause dandruff, poor skin quality, and poor response to vaccine.  The calf is unable to mount strong immunity,” Havenga says.

Copper
This important trace mineral works hand in hand with selenium and can be a contributing cause to retained placenta if copper levels are low.  “Copper deficiency is also detrimental to the calf’s immune system.  He’ll be very susceptible to scours, and to a lesser degree susceptible to respiratory disease,” Havenga says.

“If the fetus was low in copper and then after birth the calf is still low in copper, he may develop abomasum ulcers due to structural weakness in the connective tissue; it can’t stretch and contract properly.  Every time the calf gets a belly full of milk, the stomach stretches, and tears a little.  Those little tears eventually become infected.  Soon there are open sores in the gut, which may eventually perforate, killing the calf,” he says.

Copper deficiency can also lead to fragile bones and fractures.  “Several minerals play a role in early development of bone.  The bones have two components—scaffolding that gives structure, and calcification that makes it strong and hard.  The scaffolding is a combination of manganese, copper and zinc.  If that scaffolding is out of whack, bones become brittle and break easily, or joints become bigger/wider because the scaffolding is collapsing.  It’s like pushing down on a piece of clay, making it bulge outward.”

Manganese
This element is also important for strong bones, strong immune system, and for hormone production in cows and bulls.  For instance, progesterone levels in the pregnant cow are dependent on adequate manganese.
    
Secondary Deficiencies
In the Midwest a few years ago there were some calves born that looked like dwarfs.  “They were very small but all their joints were enlarged and they had contracted tendons.  Veterinarians discovered this was a secondary deficiency due to too much iron in the silage.  The iron tied up manganese in the diet,” says Havenga.

Problems can be due to primary or secondary deficiency.  “Primary deficiency is when the body does not have enough of that mineral.  We are either not putting enough selenium, copper or zinc in the diet, or cattle are not consuming the correct amount.”

Dr. Stephanie Hansen, Associate Professor, Beef Feedlot Nutrition Chair, Iowa State University, was part of the research team that looked at the manganese deficiency in those calves in the Midwest.  She did her masters work at North Carolina State University on effects of manganese deficiency and reproduction in beef heifers.  “Those heifers were still able to get bred and have normal pregnancies, but when they calved, many of their calves exhibited classical signs of manganese deficiency,” she says.

“Then the next spring I got multiple calls from veterinarians in Iowa and surrounding states and we found extensive incidence of manganese deficiency, largely in cattle that had been fed corn silage over winter,” she says.  

The corn silage was contaminated with soil, and the iron in soil becomes available during silage fermentation.  “Iron competes with manganese for absorption in the body, using the same transporter in the gut.  Manganese deficiency is more likely to come from high iron levels than from a manganese-deficient diet,” Hansen explains.

Havenga says that in recent years secondary deficiencies have increased; there is enough manganese, copper or selenium in the diet but something else is tying it up.  Molybdenum occurs in many soils (and ties up copper) but we’re seeing more problems today.  “The reason may be that certain new supplements have become very affordable such as distillers cubes that are high in protein.  Distillers grains also contain a lot of sulfur.  If we combine sulfur with molybdenum we reduce copper uptake by the body—by more than 50%,” he says.

Early Life Of A Calf
“In a normal, healthy calf with adequate mineral levels at birth, those levels drop dramatically during the first two months,” says Havenga.  “A study done by graduate student Christopher Branum at Texas A&M showed that baby calves with normal mineral levels have reduced those levels in the liver by about 75% by the time they reach 56 days of age. 

This happens because the calf is growing rapidly, using minerals for building tissue, and cow’s milk is very low in trace minerals even if she’s consuming them,” he says.

“There’s a high level of calcium in cow’s milk, but very low levels of copper, selenium, zinc and manganese.  So if the calf has low levels at birth (due to deficiencies in the cow during late pregnancy) we run into problems.  The calf is growing fast, and becomes very deficient, very quickly,” says Havenga.

Trace minerals also play a key role in hormone production.  “When a cow becomes pregnant, the hormone that keeps the fetus alive is progesterone.  Production of this hormone is regulated by the level of manganese.  If she is deficient in manganese she might not produce enough progesterone to maintain the pregnancy,” says Havenga.  Cows that are short on manganese during the winter may lose the pregnancy.

Protein Supplements
In fall and winter, most native forages and tame pastures are low in protein unless fall rains have stimulated new growth, yet many stockmen try to extend grazing as long as possible into winter because winter feeding is the most expensive part of raising cattle.  Depending on the protein content of the forage, adding a supplemental source of protein to mature, dry pastures, crop aftermath or cornstalks is generally cheaper, and just as effective, as feeding supplemental hay.

The rate of fiber breakdown affects rate of passage of ingested feed through the GI tract.  If digestion/breakdown is slow, this limits the amount of feed an animal can eat on a daily basis.  Low feed intake can cause cattle to lose body condition on dry fall pastures, at a time when they need to be building reserves in preparation for winter and for next calving. 

Mature perennial forages in the fall are typically high in fiber and low in protein, which can negatively impact feed intake because the rumen cannot adequately digest the low-quality forages.  

The first thing that happens when a ruminant is short on protein is that feed intake goes down, according to Alberta Beef and Forage Specialist Barry Yaremcio.  Cattle can’t eat enough forage to maintain themselves and they lose weight.  “With a protein supplement we are feeding the microbes.  The microbes break down feed components into the basic parts—sugars and amino acids--and then the animals build everything back for what they need,” he explains.

Supplemental protein, whether supplied with alfalfa hay, protein pellets, blocks or tubs, or high-protein by-product feeds like wheat or corn distillers grains, or home-grown feeds such as peas, lentils, fababeans or soybean screenings, can help improve digestion of low-quality forages and build body condition, “There are many options.  Use what is available and economical in your situation.   We always need to look at prices and availability.  Continuity of supply is also a major consideration when planning a feeding program.  Establish the amount of product that will be required and either lock in delivery dates or preferably take delivery of all the product that is required before it is needed.  There can be some digestive problems encountered if it is necessary to switch products halfway through the feeding period because the supply is interrupted,” he says.

“Price out the cost of protein on a per pound basis.  This is more important than the cost of the feed.  Alfalfa hay can be a good supplement but right now hay is very expensive in many places and local supplies are limited.  Trucking hay from other locations becomes prohibitive because of freight costs.  Calculate the cost of protein by the time it gets to your place,” he says.   Other sources may be more economical.  “Byproducts such as wheat distillers (40% protein) and corn distillers (30% protein) can be fed at 2 to 3 pounds of byproduct per feeding.  Feeding events can be every few days rather than daily.  There is research showing that feeding protein twice a week or 5 times in 2 weeks would be adequate,” he says.  It all depends on the type of animal being fed, but reducing the number of feedings can save time and fuel.

Supplementation will be important this year in many places.  “Dry conditions in some parts of the country, combined with lack of moisture and poor growing conditions have reduced hay and forage pasture supplies in those areas.  Pastures ran out early.  Many producers are going to market early with anything that’s open because they can’t afford to feed them.  It is important to stretch feeds as much as possible,” he says.

“In some of the harder hit areas, hay yields are 25 to 40% of normal.  Silage crops are yielding half of normal.  It may be necessary to feed pregnant cows lower quality forages or straw/grain rations and save the higher quality hay and silage for after calving.  Knowing the quality and quantity of feed available is key to developing a sound winter feeding program. Feed testing is the first step.  When looking at ration programs, pay attention to the macro minerals especially the calcium-phosphorus ratio, magnesium levels, vitamins and trace minerals.  Match purchases to the needs of the cattle and if necessary have a custom product manufactured.  Feeding a product that is convenient to use may not meet requirements.  Evaluate the fortification levels from the product tag to see if the product will work before making a purchase,” he says.
“When pastures go dry or dormant and the forage hasn’t been green for 60 or 70 days, you also need vitamin supplementation and not just protein.  Many protein tubs or lick blocks are being sold because producers feel they are doing something good for the cows, but most of these do not contain the necessary vitamins and minerals.  You need a way to figure out what to supplement with, how to provide it, what the cows need, and how to evaluate the product you put in front of them.”