Minerals and vitamins are essential nutrients required for a diverse range of functions that the body needs to carry out daily functions and processes.  Minerals are important in cattle for maintaining healthy animals and reaching optimal growth and reproductive rates.  The levels of minerals needed depend on the age of the animal, stage of production, diet and what is provided by the environment.  High quality forages and grains can provide a large amount of necessary minerals.  Cattle need both macrominerals and trace minerals.  Macrominerals include calcium, magnesium, phosphorus, potassium, sodium, chlorine and sulfur and trace minerals include iron, manganese, copper, zinc, selenium, cobalt, iodine, chromium, and molybdenum. Many minerals are available in the soil and therefore needs of supplementation can vary by geographic region.

At the Kansas Stave Veterinary Diagnostic Laboratory (KSVDL) during 2012-2016 we have seen several cases of acute hepatic necrosis in which the common thread in the history was being worked recently for vaccination and injection with supplemental mineral.  The values for minerals that were high on Trace Mineral Panels are listed in Table 1.  In these cases, calves ranged from 30 days of age to 6 months of age.  Calves in these cases were getting multiple sources of minerals which included oral free choice mineral, injectable, high protein top dress, liquid supplement, and probiotic with minerals.  In some cases these calves were given 2.5 times the labeled dose for injectable on top of having other sources of minerals.  Another factor to consider in these cases would be the level of minerals in the environment and roughage. 

Over supplementation of minerals can cause various lesions and death.  Acute selenium toxicosis usually manifests within a few hours to two days after a toxic level is reached.  Major lesions included pulmonary edema, pulmonary congestion, pulmonary hemorrhage, hepatic necrosis, myocardial necrosis, myocardial hemorrhage, and renal necrosis.  Acute copper toxicity results in severe hemorrhagic gastroenteritis and congestion of the liver, kidneys and spleen, while chronic copper toxicity results in gunmetal-colored kidneys, port-wine-colored urine, icterus, an enlarged spleen, and hepatic and renal necrosis.  Toxicity from iron can result in enteritis, liver necrosis, icterus and hemoglobinuria.  In addition, toxicity from zinc will result in lesions of gastroenteritis, renal necrosis and liver necrosis.

Mineral toxicities can result in liver necrosis in cattle, which is illustrated by these cases submitted to KSVDL with histories that indicated mineral over supplementation.  In many cattle operations, cows are supplemented with an oral source and calves are given an injectable, in addition to other sources.  Multiple sources of mineral supplement and/or large injectable doses, can result in an overdose of mineral leading to acute liver necrosis and/or other lesions, depending on the single or combination of toxic levels of minerals reached.  At KSVDL we have seen the severe cases that have resulted in death, but one should consider if toxic doses are given but not at a level to cause death, decreased performance or a change in animal behavior may result.  It is important to follow label directions and   to consult a bovine nutritionist about mineral supplementation.  In addition, weather conditions and fertilization can change the levels of minerals in feed and soil, therefore, checking the mineral status of feed and soil may need to be routinely performed.  If you suspect a case of mineral supplementation, the samples to submit are fixed liver and kidney, fresh liver and kidney, whole blood, serum, and feed/supplements, need to be submitted to KSVDL or your diagnostic laboratory to adequately examine the mineral levels in a case of suspected toxicity.  Providing a thorough history will aid in reaching a diagnosis.

Thank you to Dr. Steve Ensley at Iowa State Veterinary Diagnostic Laboratory for reviewing the article.

 

Table 1.  Cases with minerals in the toxic range.

Case

Organ

Mineral

Result

Reference range

Toxic Range

Dry Weight/Wet Weight

Case 1

Liver

Selenium

5.52 mg/kg

0.25-0.5

>2.8

Wet

Case 2

Liver

Selenium

3.2 mg/kg

0.25-0.5

1.25-7

Wet

 

Kidney

Copper

12.8 mg/kg

4-6

3.4-11.7

Wet

Case 3

Liver

Selenium

5.97 mg/kg

0.25-0.5

1.25-7

Wet

 

Kidney

Copper

15.28 mg/kg

4-6

>10

Wet

Case 4

Liver

Selenium

18.6 ug/g

1.5-3.5

 

Dry

Case 5

Liver

Selenium

16.8 ug/g

1.5-3.5

 

Dry

Case 6

Serum

Selenium

440 ng/ml

65-100

   
   

Copper

1.34 ug/ml

0.6-0.9

   
   

Iron

412 ug/dl

110-180

   
 

Liver

Selenium

37.17 ug/g

0.6-3.30

 

Dry