By Jerad Jaborek
White muscle disease (WMD) is a nutritional myopathy sometimes called nutritional myodegeneration due to the breakdown of the muscle as the result of selenium or vitamin E (tocopherol) deficiency. This disease can occur in newborn calves and has been reported in yearling and adult cattle.
White muscle disease occurs more frequently after cattle are turned out to pasture and their exercise demands increase. Affected animals are often unable to rise or exhibit a stiff gait while walking because the disease can affect the heart, tongue, diaphragm and other large muscles in the legs and back. When WMD affects the heart, calves are usually found dead or in respiratory distress and die soon after due to sudden heart failure. Another sign of selenium deficiency can be an increase in the occurrence of retained placentas from cows during the calving season.
WMD-affected muscles have a pale discolored appearance with white streaks in the muscle bundles that are indicative of calcification and immune cell infiltration. Measuring creatine phosphokinase concentrations in blood plasma can be an effective indicator of myodegeneration, where animals with WMD will have a (several thousand-fold) greater concentration of creatine phosphokinase. Measuring plasma selenium and α-tocopherol concentrations can be used to determine general selenium and vitamin E status in the body. However, plasma glutathione peroxidase concentration can be used as a faster and less expensive indicator of selenium status determination, with less than 20 units of GSH-PX activity/mg hemoglobin being considered low status. Cows with less than 0.05 ppm Se in the blood are considered selenium deficient and on the verge of WMD onset. Vitamin E deficiency can be recognized at less than 2.0 ppm α-tocopherol in the blood.
Selenium and vitamin E both play important roles in the body to protect it from oxidative damage. Glutathione peroxidase is a selenium-dependent enzyme that aids in the reduction of oxidative radicals to protect cells from oxidative damage. Vitamin E acts similarly as an antioxidant to prevent oxidative damage to parts of the cells in the body. Selenium is also a major component of selenoproteins that help to regulate the mitochondria function and the energy transport system, oxidative damage, and calcium homeostasis for proper muscle contraction and function.
Supplying selenium and vitamin E to your cattle can be accomplished by two approaches. The first is to supply enough selenium and vitamin E through the diet. Unfortunately, Michigan happens to be one of the states that is largely comprised of selenium deficient soil (see the map from U.S. Geological Survey). Therefore, crops grown in Michigan for livestock feed are selenium deficient as well. Vitamin E concentration in feedstuffs can be greatly impacted by storage conditions.
Selenium can legally be fed at the rate of 0.3 mg/kg of dry matter (DM) or 3 mg per head per day. Growing cattle require 0.1 mg Se/kg DM, while the max tolerable limit has been set at 5.0 mg Se/kg DM. Selenium can be fed in inorganic forms such as sodium selenite and sodium selenate or organic forms such as selenomethionine and selenocystine. Dietary selenium retention has been found to be greater from organic sources compared with inorganic sources. High levels of dietary sulfur and iron have been known to decrease the absorption of selenium in reported studies.
The requirement of vitamin E is less well known because of its similar functions as an antioxidant when compared with selenium. However, the current recommendation is between 25 to 35 mg IU of vitamin E/kg DM for normal healthy cattle. Research has demonstrated greater concentrations of dietary vitamin E (400 to 500 IU/day) can be beneficial to highly stressed calves.
The second and fastest approach to supplying selenium and vitamin E is to deliver it via injection. There are commercial products on the market that contain a combination of selenium and α-tocopheral such as BO-SE and MU-SE for the intent of treating and preventing WMD in calves and weanling/adult cattle. Make sure to work with your veterinarian to develop a plan with proper timing of selenium-tocopheral administration for the prevention of WMD. Selenium boluses that release selenium slowly over time may be another consideration for selenium supplementation for cattle operations in selenium deficient areas.
If you suspect a selenium deficiency in your herd, consult with your veterinarian, nutritionist and MSU Extension beef team contact. They can help devise a plan to assess the situation by collecting and analyzing blood samples, analyzing feed ingredients in cattle diets, and scheduling necropsies for disease identification.
Source : msu.edu