Selenium deficiency in the equine

Graduation date: 1983Whole blood selenium levels were measured in 207 horses, representing 41 ranches and 11 regions throughout Oregon. Age, sex,\ud diet, and history of disease were recorded. Diet was divided into\ud three categories; local feed only, commercial feed, and Se supplemented feed. Region (p<.01), diet type (p<.01), and a region x diet\ud interaction (p<.01) affected blood Se levels. For horses fed only\ud local diets, region and ranch were found to affect Se levels also\ud (p<.05). Least squares means for selenium among regions ranged from\ud .045 ppm to .461 ppm Se. Feeding local diets resulted in lowest\ud blood Se levels (.058 ± .006); feeding commercial diets resulted in\ud intermediate Se levels (.129 ± .012); and feeding Se supplemented\ud diets resulted in highest Se levels (.206 ± .012). Age (p<.07)\ud affected Se levels (positive relationship), whereas sex did not.\ud Disease was recorded as presence or absence of disease of any sort\ud and also categorized into three classifications; muscle-related\ud diseases, reproductive-related diseases, and all others. Selenium\ud was found to be negatively associated with overall incidence of\ud disease (p<.05). Low Se level was associated with higher incidence of reproductive-related disease, but there was no association of\ud selenium level with muscle-related or other diseases.\ud In a study involving ten selenium supplemented (.15 ppm) pony\ud mares and ten low selenium mares (.02 ppm) and their foals, it was\ud shown that diet affected (p<.01) both mare Se and glutathione per-oxidase but month of gestation affected only glutathione peroxidase.\ud Week of lactation influenced (p<.01) mare blood Se, with the Se\ud supplemented mares showing a decline in blood Se levels. Milk Se\ud levels were low and not affected by either diet or week of lactation.\ud Diet of the dam influenced the levels of foal blood Se, serum glutamic\ud oxaloacetic transaminase (SGOT) and creatine phosphokinase (CPK).\ud Foals from low Se mares had increased levels of the muscle-related\ud enzymes, SGOT and CPK, until seven weeks of age, when the levels\ud decreased to the levels of the foals from Se supplemented mares. Mare\ud diet had no effect on foal weight or height