Selenium is a chemical element with symbol Se and atomic number 34. It is a nonmetal with properties that are intermediate between the elements above and below in the periodic table, sulfur and tellurium.
Selenium is one of the trace elements or micronutrients vital to the biological process of all animals on earth. It is especially vital to young ruminant stock to prevent the development of white muscle disease, difficult breeding, unthriftiness, and even death. Evidence of selenium deficiencies in the soils of the Northeast United States is well documented. These symptoms are most often subclinical (not noticeable) in mature animals and often cause muscle tremors, motor disturbances, and hind end paralysis in animals under 8 weeks of age. The mechanism of this shortage stems from selenium’s role in binding with free radicals working in conjunction with vitamin E to keep the animals muscles working properly.
The USGS survey map for our area lists the average level of selenium in the surrounding counties. Soils containing less than 0.5 ppm total are classified as Se deficient.
Ulster County: 0.29 ppm
Orange County: 0.33 ppm
Sullivan County: 0.24 ppm
Columbia County: 0.44 ppm
As you can see, all of the counties in our area would meet criteria for being selenium deficient although there are significant variations in the soils within each of the counties. Now that we have proved that we are growing in soils deficient in selenium, what can we do to ensure that we are doing our best to keep our animals healthy? There are a few ways to increase the amount of this micronutrient that your stock are consuming but only two are viable and legal in the state of New York so we will stick with those methods.
On one hand you can administer selenium injections and this is most often used for young animals that are at risk of developing white muscle disease. You will need to contact a veterinarian for this service as there is a real risk of toxicity with this method. Although effective, this is not a long term solution as the injectable form is not as long lasting as the organic form.
The other option is to provide the trace element via mineral blocks or as part of their total mixed ration. These organic forms of selenium allow the chemical to build up in the animal and are longer lasting and less toxic than synthetic forms of the supplement. The biggest drawback to this method it that you really don’t know how much each animal is taking in, which can lead to variable amounts in your herd or stock. It is also important to make sure that your mineral supplementation is covered from the rain as selenium is at risk of quickly leeching out of the blocks or free range mixes when exposed to the elements.
I know this seems like just one more thing to worry about but this issue has come to our attention here at CCE for two reasons. One is that we are deficient in selenium in this area and this could be contributing to some producers calving or lambing issues. Secondly, the symptoms of white muscle disease in young animals can mimic the clinical signs of certain parasite infestations. This has led us to include this factor when we are investigating parasite problems on area farms. So as we all head out to pasture and onto the verdant grasses created by the last couple of rainy weeks, remember to plan ahead to combat selenium deficiencies before they become a problem for you and your stock.