Selenised compressed salt blocks for selenium deficient sheep

Salt blocks containing 30 or 120 ppm selenium were tested as the sole supplement for sheep farmed in a selenium-deficient area of New Zealand (Te Anau). Both concentrations were unsatisfactory in preventing selenium deficiency. In five trials using 120 ppm Se salt, the highest percentages of sheep found to be deficient were 31% (lambs) and 32% (ewes). If sheep which were classed as marginally deficient were included these percentages became 63% (lambs) and 56% (ewes). Some instances of selenium-responsive unthriftiness in lambs were encountered, and in one trial there was the possibility of selenium-responsive infertility having contributed to the low lambing performance of the ewes. There was no evidence of white muscle disease. Selenium levels in the liver and kidney were well below the permitted maximum. Because selenised salt failed to eliminate selenium deficiency, its use as a sole supplement for sheep grazing selenium deficient pasture is not recommended.

Selenium accumulation in beef: effect of dietary selenium and geographical area of animal origin

Selenium (Se) is an essential nutrient with multiple human health benefits; the single most important dietary source of Se is beef. The Se content of beef varies, and cattle fed a high selenium diet may have Se concentrations in beef that are well above average. Such beef is potentially a unique supplemental source of dietary Se. To examine factors affecting Se accumulation in beef, 16 steers (initial wt 374.4 +/- 33.7 kg) were taken from seleniferous or nonseleniferous areas and fed in a 2 x 2 factorial design with diets high or moderate in Se (11.9 or 0.62 mg Se/kg diet). Diets contained 50% alfalfa, 25% wheat, and 25% corn on a dry matter basis. All dietary Se was from agricultural products, and Se in the high Se diet was primarily from high Se wheat and alfalfa hay. A loin muscle biopsy was taken at the start of the trial to determine initial Se content of beef. Steers were slaughtered after 14 weeks of the trial, and edible carcass (round, sirloin, shoulder clod, and ribeye) and organ samples were collected. Diets did not affect growth or feed intake (P > 0.05), and Se toxicity signs were not observed. Different cuts of meat had similar Se concentrations, and the Se content of all cuts was increased by both high dietary Se and high Se background. Except for liver and kidney, Se in tissues was increased by seleniferous background (P < 0.02) and high dietary Se (P < 0.001). Kidney Se concentrations of animals fed the high Se diet were lowest in animals from seleniferous areas (P = 0.04), suggesting a possible adaptation to the high Se diet. These results demonstrate that cattle fed diets high in Se from agricultural products will accumulate substantial amounts of Se in the beef without developing signs of Se toxicity and that prior Se status regulates Se accumulation in some organs. They further demonstrate that management practices may be altered so as to make beef a significant source of dietary Se.

Selenium and vitamin E

Deficiency of selenium and vitamin E has recently been identified as a major health concern of sheep producers in certain regions of the United States, and familiarity with published data on these nutrients seems to be of value to small ruminant practitioners. This article begins with a description of the biochemical roles and metabolism of selenium and vitamin E. A literature review follows in which the influence of these nutrients on the musculoskeletal, reproductive, and immune systems, as well as on flock productivity, is discussed. Methods for detection of deficiency and supplementation strategies are also described.