Selenium Supplementation of Diets for Sheep and Beef Cattle

Abstract

Two experiments with growing lambs and one with growing beef cattle were conducted to determine the effect of supplemental selenium from sodium selenite upon performance and tissue selenium concentration when these animals were fed pelleted diets containing low or adequate levels of selenium from natural sources. Natural selenium levels were either 85 or 199 ppb in the basal diets used in the beef experiment and one sheep experiment. The two basal diets were formulated identically except that Michigan corn was used to produce the low selenium diet while South Dakota corn was used to produce the adequate selenium diet. Supplements of 100 or 200 ppb of selenite selenium did not significantly influence weight gain, feed consumption or gain/feed. Serum, sternomandibularis muscle and liver selenium concentrations were generally increased when supplemental selenium was added to the low selenium diet; however, these values were less than those obtained when equal dietary selenium concentrations were derived from natural sources. The second study with sheep confirmed that supplemental selenium can be safely provided by adding 30 ppm of selenite selenium to trace mineral salt fed ad libitum. It was concluded that there is little animal or human health hazard associated with supplementing the diets of slaughter lambs or cattle with selenite selenium equivalent to .1 ppm (100 ppb).