The silent saboteurs: Prevent trace mineral deficiencies & boost herd health & production

High production dairy cows are metabolic athletes with unique nutritional challenges that producers must be aware of to maintain herd health, trace mineral balance and optimal milk production.

There are currently 1.2 million dairy cows producing an average of 22,516 lbs. of milk per cow within Connecticut, Vermont, New Hampshire, New York, Pennsylvania and Maine (Service, 2023). There is a variety of production strategies including organic, non-organic, grazing and non-grazing herds with different nutritional needs. All these Northeast herds share a commonality: every cow is at risk of being insufficient or deficient in micronutrients including trace minerals.

Deficiencies of trace minerals are the cause of unknown illness in high production cattle. Expensive veterinary bills and animal illness can be avoided when we take a step back and evaluate the nutrition being provided and understand the cows’ varying needs, dietary inputs and rumen physiology.

Ruminants have a unique gastrointestinal physiology amongst mammals and distinct nutritional requirements that are met through specific ingredients. Dairy cows’ four-chambered stomachs have the ability to digest and process high fiber forages. The rumen is where microbes convert forages and concentrate into macronutrients that the cow can utilize.

Past the stomach, the remaining gastrointestinal physiology is like a non-ruminant digestive tract where the nutrients and minerals are absorbed by the small intestine (Smith, 2024). Once absorbed, these nutrients are utilized to create milk and maintain the cows’ body condition, but every cow has slightly different nutritional needs.

Every cow has a distinct nutrient requirement depending on breed, age, body size, physiological state, lactation cycle and production level. The nutritional requirements of cows are separated into macronutrients (carbohydrates, lipids and protein) and micronutrients (vitamins and minerals). Minerals, however, are distinct from other nutrients; they are inorganic and cannot be created, and they originate from the soil. Certain minerals are necessary for metabolic processes in high demand dairy cows and preventing disease.

When dairy cows do not receive adequate minerals in their diet, they may develop health problems. Insufficiency occurs when cows consume minerals below requirements without obvious clinical signs; deficiency occurs when requirements are unmet and visible illness develops. Mineral deficiencies increase disease susceptibility, disrupt reproduction and reduce growth or weight gain (Smith, 2024).

In the U.S., cattle are commonly deficient in the trace minerals zinc (Zn), manganese (Mn), copper (Cu), iodine (I), cobalt (Co) and selenium (Se), which require careful monitoring by producers (Arthington, 2021).

Soil mineral profiles in the Northeast often lead to cattle being deficient or insufficient in Zn, Mn, Cu and Se. General deficiency symptoms include stunted growth, impaired fertility, poor hair coat quality, decreased milk production, increased illness and pica.

Zinc plays a vital role in rumen function, forage digestion, energy metabolism and immune health. Zinc deficiency commonly results from inadequate dietary inclusion or mineral premix omission. In some cases, dietary Zn is present, but absorption is reduced due to antagonistic minerals such as calcium (Ca) and Cu. Excessive Cu combined with low Zn levels increases miscarriage risk (Żarczyńska K., 2017).

Manganese deficiency is associated with silent estrus, lowered conception rates and increased abortion risk. High dietary Ca or phosphorus can interfere with Mn absorption and contribute to deficiency. Copper deficiency results in reduced growth rates, poor feed efficiency, lameness, weakened immune response, sudden death and impaired fertility.

Selenium insufficiency leads to reduced growth, compromised immune function and poor reproductive performance. Clinical Se deficiency can cause white muscle disease, which damages cardiac and skeletal muscles and is commonly associated with concurrent vitamin E deficiency (Hall, 2021).

As many micronutrient deficiencies share overlapping symptoms, identifying the exact cause can be challenging. When evaluating deficiency risk in a herd, diet assessment is the first critical step. Forage and concentrate samples should be collected and sent to a laboratory for mineral analysis, then compared with National Research Council (NRC) or industry guidelines.

Diets must meet mineral requirements for each group of cows based on age, production level and physiological stage. Soil testing is also important for grazing herds to determine whether additional supplementation is necessary.

Beyond diet and soil evaluation, individual animal assessment can be conducted using blood serum mineral testing. Producers should coordinate with local ag laboratories for proper blood collection protocols and mineral analyses (Schaeffer, 2025). If pre-weaned calves exhibit deficiency symptoms, it often indicates depleted maternal mineral reserves.

Once missing trace minerals are identified, selecting an appropriate supplement requires several considerations. Cost is an important factor, as products vary widely in price, branding and formulation. The most important factor is that the supplement supplies the required minerals at appropriate concentrations clearly listed on the label.

Mineral form also matters; organic trace minerals are generally more bioavailable and beneficial than inorganic forms. Examples include zinc proteinate, manganese methionine and selenium yeast.

Another consideration is whether a complete mineral mix is needed to supply multiple deficiencies simultaneously. Mineral premixes can be incorporated into total mixed rations following manufacturer-recommended inclusion rates, such as 1 lb. of premix per 1,000 lbs. of feed. In grazing systems, mineral supplements can be delivered through free-choice mineral feeders, salt blocks or water supplementation. Most mineral products are readily available at local feed suppliers.

Regular monitoring and recordkeeping strengthen mineral management programs by allowing producers to track intake, adjust supplementation seasonally and respond quickly to changing forage quality. Collaboration with veterinarians, nutritionists and Extension specialists improves decision making, reduces unnecessary costs and supports long-term herd productivity, welfare and sustainability through consistent evaluation, education and practical application on modern dairy operations across regions and herd sizes nationwide systems.

Proactive evaluation of diets, soils and individual animals, combined with strategic supplementation of bioavailable trace minerals, enables producers to prevent subclinical deficiencies, protects cow health and supports consistent milk production across diverse dairy management systems.

by Jazlyn Hoadley & Andrew Magnuson, SUNY Cobleskill