Zinc methionine may improve hoof quality and milk production of cows, though more research on this product is needed. Dry cows should be supplemented with three to five milligrams of selenium per day, and lactating cows with six to eight milligrams daily when soils are deficient. Selenium deficiency has been associated with white muscle disease in calves and selenium treatment may improve reproductive efficiency and reduce retained placentas in dairy cattle. Adequate dietary selenium may also contribute to lower incidence of mastitis along with proper milking management and environment. However, selenium should be used with caution because some soils are high in selenium and it is toxic if used in excess.
Selenium is reported to be high in some areas in Nebraska.
Levels of greater than 2 ppm cause loss of appetite, loss of hair from the tail, sloughing of hooves, and even death. Use of Chelated Minerals. Use of mineral chelates, or organic mineral complexes, has increased performance and decreased somatic cell counts in milk compared to inorganic forms of the same mineral in some research trials. Chelates of zinc, copper, manganese, iodine, and selenium have given variable milk production responses, and their practical utility is currently undecided. Before any definitive recommendations can be made, further research is needed to better define the management conditions where positive production or health responses are likely.