Cobalt (Co)

0.1–0.2

Component of vitamin B12 (ruminants only)

Megaloblastic anemia; enzootic marasmus (ketosis), reduced growth, body weight

Cobalt needs to be supplied to rumen microbes; toxicosis unlikely

Copper (Cu)

10–15

Hemoglobin synthesis; bone formation; pigmentation; myelin formation; oxidation-reduction reactions; immune function

Achromotrichia; neonatal ataxia (swayback); infertility; hypochromic-microcytic anemia; profuse diarrhea; immune failure

High iron, zinc, and selenium reduce availability; excess molybdenum and sulfur inhibit utilization and storage in ruminants; toxicity variable in species, results in hemolytic crisis

Iodine (I)

0.5–1.0

Thyroxine formation

Goiter; stillbirths, infertility; malformations, hairless neonates; immune failure

Dietary goitrogens inhibit function; high intakes reduce uptake efficiency; toxic intake results in goiter, fetal malformations

Iron (Fe)

50–100

Cellular respiration, oxygen transport

Hypochromic-microcytic anemia; easily fatigued

High calcium may decrease absorption; copper status influences metabolism; excessive amounts are pro-oxidants; interferes with copper metabolism

Manganese (Mn)

20–40

Bone formation; activator of enzymes with carbohydrate, lipid, and protein metabolism

Crooked calf disease; impaired fertility; poor growth; impaired immune function

Excess calcium and phosphorus decrease availability; toxicosis unlikely; may interfere with other minerals

Selenium (Se)

0.3

Antioxidant—cellular iodine function, immune function

White muscle disease; acute death; retained placenta; impaired immune function

Sulfate, acid soil conditions interferes with selenium availability; maximum tolerable level 2 mg/g in nonruminants— alkali disease of horses (chronic toxicosis); acute toxicosis from parenteral products— respiratory collapse

Zinc (Zn)

30–60

Component of >90 enzymes influencing all aspects of metabolism immune function

Anorexia; parakeratosis; poor skin and hair formation; male infertility; impaired immune function

High calcium, phytates or oxalates bind zinc; high zinc interferes with copper metabolism