Mineral Nutrition Through Winter Months
Mineral Nutrition Through Winter Months
During the winter, beef cattle often rely on dormant pasture, stockpiled forage, hay, or other stored feeds. These feeds usually have lower levels of protein, energy, vitamins, and minerals compared to actively growing pasture. Cold weather also increases nutrient requirements for cattle. As the temperatures drop and we approach winter, we should take a moment to think about the minerals our cattle need, and get a plan to provide both macronminerals and microminerals.
Minerals are essential for the growth, reproduction, immunity, and overall health of beef cattle. While forages and feeds provide some minerals, the levels vary widely depending on soil type, season, and plant species. Deficiencies or imbalances in mineral intake can lead to reduced conception rates, weak calves, poor weight gains, and increased disease susceptibility.
For the most part, minerals and nutrients can be broke down into macrominerals and micominerals. While both categories are necessary for optimum health of cattle, we will see the biggest impacts when lacking a micromineral over a micomineral. Macrominerals are required in larger amounts, measured in grams per day. Microminerals, also known as trace minerals, are needed in much smaller amounts, measured in milligrams per day, but they remain equally important.
Macrominerals
When it comes to macrominerals, calcium is one of the most vital for beef cows. Calcium (Ca) is necessary for bone formation, muscle function, milk production, and nerve transmission. According to National Research Council (NRC) standards, lactating beef cows require higher levels of calcium to prevent milk fever and skeletal problems. Signs of calcium deficiency include poor bone growth, weak calves, and reduced milk production.
Phosphorus, magnesium, potassium, sodium, chloride, and sulfur are essential minerals that support key functions in beef cattle. Phosphorus plays a vital role in energy metabolism, bone development, and reproduction. Research from the University of Florida shows that supplementing phosphorus in deficient areas improves conception rates and increases calf weaning weights. Without adequate phosphorus, cattle may suffer from poor reproductive performance and may exhibit abnormal behaviors such as chewing on wood or bones, a condition known as pica.
Magnesium is necessary for muscle and nerve function and supports many enzyme activities. A deficiency in magnesium can lead to grass tetany, particularly in the spring when cattle graze on lush, high-potassium forage. Kansas State University research has found that feeding high-magnesium mineral mixes in the spring can greatly reduce the occurrence of this condition. Potassium, which regulates fluid balance, nerve impulses, and muscle contractions, is usually adequate in most forages, although deficiencies can arise in drought-stressed or winter stockpiled forage. Sodium and chloride, typically provided through common salt, are essential for maintaining osmotic pressure and proper pH balance in the body. Sulfur is another critical mineral, supporting protein synthesis and aiding rumen microbial activity necessary for digestion and overall health.
Microminerals & Trace Minerals
Copper, zinc, selenium, manganese, cobalt, iron, and iodine are key trace minerals essential for the health and productivity of beef cattle. Copper plays an important role in enzyme systems, immune function, and reproduction. Research from South Dakota State University has linked copper deficiency to lower conception rates and increased disease susceptibility, with absorption often reduced by high levels of molybdenum, sulfur, or iron in forage or water.
Zinc is another critical mineral, supporting skin integrity, immune function, hoof health, and sperm production. Studies have shown that supplementing zinc can improve hoof strength and fertility in bulls. Selenium functions as a powerful antioxidant, working with Vitamin E to support immune function and reproduction. University of Idaho research demonstrates that selenium-deficient cows are more likely to experience retained placentas and produce weak calves. However, selenium must be carefully managed, as excessive intake can be toxic, leading the FDA to set a supplementation limit of three milligrams per head per day.
Other important trace minerals include manganese, cobalt, iron, and iodine. Manganese is needed for skeletal development, reproduction, and enzyme activity, with deficiencies resulting in poor conception rates and weak calves. Cobalt is crucial for rumen microbes to synthesize Vitamin B12, which supports energy metabolism; a lack of cobalt can cause reduced appetite and weight loss. Iron is essential for hemoglobin formation and oxygen transport, but excessive iron can interfere with copper absorption. Iodine is necessary for thyroid hormone production, which regulates metabolism, and deficiency can lead to goiter and weak calves. Together, these trace minerals are vital for maintaining herd health, optimizing reproduction, and ensuring strong calf performance.
Vitamins
Vitamins can also be limiting in winter diets. Vitamin A is typically deficient in dormant forage but is essential for reproduction, immunity, and calf health. And Vitamin D generally synthesizes when exposing cattle to sunlight, but supplementation may be necessary for cattle in confinement. While Vitamin E works closely with selenium to support immune function and is often low in dry forage. Supplementation can be provided through injectable vitamins at weaning or calving, or through mineral mixes. University of Idaho research indicates that Vitamin A supplementation decreases the incidence of retained placentas and weak calf syndrome.
A practical winter supplementation program should begin with testing forage for protein and energy to determine deficiencies. Protein should be the first supplemented if crude protein levels are below 7 percent. Energy supplements should be added if cows are losing condition, particularly if their Body Condition Score drops below 5. Balanced, free-choice minerals should be available to cattle throughout the year, and Vitamin A, D, and E should be included in the winter ration. Finally, adjust supplementation programs around the cattle’s stage of production and the severity of weather conditions.
Mineral Testing to Prevent Deficiencies
The NRC’s Beef Cattle Nutrient Requirements (2016) is the primary reference for determining mineral needs in cattle. Research from the University of Florida and Texas A&M confirms that mineral deficiencies are a major cause of reduced reproductive efficiency. The University of Nebraska has shown that implementing free-choice mineral programs significantly improves pregnancy rates and calf survival in deficient regions. Bioavailability studies from the University of Kentucky and South Dakota State University indicate that organic (chelated) minerals may provide better absorption than inorganic forms, particularly under stress conditions.
Mineral testing is one of the most effective tools that producers can use to ensure proper cattle nutrition, especially during the winter months when forage quality declines. Identifying nutrient gaps before they affect performance helps maintain herd health, improves reproductive success, and protects profitability.
Macronutrients such as calcium, phosphorus, magnesium, potassium, sodium, and sulfur are critical for optimal cattle performance. Without accurate testing, deficiencies in these nutrients often go undetected until they lead to production losses. Forage testing and periodic blood or liver mineral analysis provide a clear picture of which nutrients are lacking and allow producers to supplement effectively.
Energy (Total Digestible Nutrients, TDN) and protein (Crude Protein, CP) are frequently low in dormant winter pastures, as shown through forage testing. Low levels of energy and protein directly affect body condition, milk production, and reproduction. Research from the University of Nebraska shows that cows calving at a body condition score (BCS) of 4 had pregnancy rates that were 30–40 percent lower compared to those at a BCS of 5–6.
Phosphorus deficiencies are commonly found through soil and forage testing, particularly in low-fertility areas. Supplementing phosphorus in deficient regions has been shown to improve pregnancy rates by up to 20 percent and increase weaning weights by 15–30 pounds per calf, according to research from the University of Florida.
Calcium levels can also be identified as low through testing, particularly in harvested feeds such as corn silage. Adequate calcium supports bone growth, milk production, and overall herd productivity. Data from the National Research Council (NRC) indicates that calcium-deficient diets can reduce growth rates by 10–20 percent in growing cattle.
Magnesium deficiencies, can lead to grass tetany in spring and subclinical losses in the winter, are also detected through testing. Iowa State University Extension reports that prevention through proper supplementation can save $10–$20 per cow annually.
Testing also ensures the balancing of the sodium, chloride, and sulfur levels. Imbalances, particularly high sulfur levels, can interfere with copper absorption, which compromises immunity and reproduction.
Undetected deficiencies can be costly. Poor nutrition results in lower conception rates, which can cost $60–$100 per cow for each missed cycle, according to the University of Missouri Extension. Reduced weaning weights are another cost, as proper supplementation can add 20–50 pounds per calf, worth $40–$100 more per calf, according to Kansas State University. In addition, undernourished cows produce weaker calves that are more prone to sickness and death, increasing health costs for the producer.
Conclusion
Mineral testing offers a proactive approach to winter nutrition management. By analyzing forage, soil, and animal mineral status, producers can tailor supplementation programs to meet herd needs, prevent costly deficiencies, and maximize performance. In today’s cattle industry, where margins are tight, testing is not simply an expense—it is an investment in herd productivity and profitability.
Producers should begin by testing forage and water to identify potential deficiencies or antagonists such as sulfur or iron. A balanced, free-choice mineral mix formulated for the region should be provided at all times. Maintaining a calcium-to-phosphorus ratio of approximately 2:1 is ideal. Magnesium levels should be increasing in the spring to prevent grass tetany. Consider organic trace minerals for high-value animals or those under stress from breeding, transport, or weaning. Finally, minerals should be available to cattle year-round, and especially in the fall and winter, not just during grazing season.
Minerals are commonly deficient in winter diets because the mineral content of dormant pasture and hay declines. Phosphorus is one of the most frequently deficient macrominerals in winter and plays key roles in reproduction and energy metabolism. Trace minerals such as copper, zinc, and selenium are often lacking as well, and these are essential for immune function, reproduction, and calf health. Supplementation with a free-choice mineral mix with proper formula is an effective way to address these deficiencies. Research from the University of Florida and Texas A&M demonstrates that mineral supplementation improves reproductive efficiency and reduces the incidence of calf illness.
By Jessica Graham
November 2025
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