Absorption of Excess Selenium and Sulfur by Plants and Animals

Abstract

High concentrations of selenium (Se) and sulfur (S) often occur in over-burden soils and underlying shales associated with western coal mining areas. Knowing the ·role of Se and S in the soil-plant-animal system is important for proper management of mine spoil reclamation. This paper will discuss recent findings about Se and S forms in soil, their absorption and accumulation by plants, and their subsequent toxicity to grazing animals. Selenium absorbed by the accumulating plants is generally metabolized to non-protein forms, while that absorbed by the non-accumulating plants occurs predominantly as selenomethionine. Selenomethionine is readily absorbed by animals. In animals, both acute and chronic forms of selenosis are known. Death occurs when a large dose of highly-available Se is ingested. One chronic form includes symptoms of inappetence, hair loss, hardening and extension of nails and hooves, reduced weight gains, and poor reproductive performance. Beath and Rosenfield identified "blind staggers" as another form of selenosis, but this disorder; more appropriately called polioencephalomalcia (PEM), occurred only in ruminants. However; the historical association of selenosis to blind staggers has been questioned. Recent experimental evidence has shown that PEM is likely caused by excess SO,. Cases of this disorder have been documented in the USA and Canada when ruminants have high S intake from herbage and/or drinking water. Western mine reclamation decisions should consider the potential for not only excess Se, but also excess SO 4 in water, soil, and plants.Additional

Animal health problems caused by silicon and other mineral imbalances

“…A blind staggers, or more correctly, polioencephalomalacea may occur if ruminants ingest excess sulfate sulfur (James et al 1994, Mayland 1995, O'Toole et al 1996. This occurs when ruminant organisms reduce SO4 to the toxic HI S form.…”

“…This occurs when ruminant organisms reduce SO4 to the toxic HI S form. Sulfate in drinking water should be considered suspect in these cases (Mayland 1995). Interactions of S x Se may occur when S fertilization results in forage crop yield response.…”

Journal of Range Management, Volume 54, Number 4 (July 2001)

“…Other factors that reduce Mg availability to ruminants include high concentrations of N and low concentrations of total soluble carbohydrate. Prudent use of N and K fertilizers is warranted to minimize risk of grass tetany (Mayland andWilkinson 1989, Mayland et al 1990). Aluminum in acid soil solutions may also reduce Ca and Mg uptake by cool season grasses and increase susceptibility to grass tetany (Rengel and Robinson 1989).…”

“…Progress has been made with Italian ryegrass (Lolium multiflorum Lam.) Baker 1991, Moseley andGriffiths 1984), perennial ryegrass (Lolium perenne L.) (Binnie et al 1996), and tall fescue (Mayland andSleper 1993, Crawford et al 1998). The new cultivars have resulted in reduced values of K/(Mg+Ca) in forage, increased levels of blood plasma Mg in animals, and in high risk situations these high magnesium cultivars have reduced the incidence of grass tetany death losses by grazing animals.…”

“…A blind staggers, or more correctly, polioencephalomalacea may occur if ruminants ingest excess sulfate sulfur , Mayland 1995, O'Toole et al 1996. This occurs when ruminant organisms reduce SO 4 to the toxic H 2 S form.…”