Effects of oral and parenteral selenium supplements on residues in meat, milk and eggs

Oral and parenteral preparations of Se are used worldwide to prevent and treat nutritional muscular dystrophy and other Se deficiency syndromes. There are extensive published data on the effects of oral supplementation on Se residues in food animal products. Very little published data exist on the effects of parenteral administration on Se residues, even for cattle and swine in which parenteral preparations are used extensively. The distribution of Se into kidney and liver appears to be equivalent for both forms of supplementation. Elimination of Se in milk is greater after parenteral administration and correlates with high plasma Se levels, however the milk excretion drops quickly and after 4 d returns to control levels (Little et al. 1979). Of particular interest is the finding that up to 18% of Se in an oral diet may be excreted in milk (Maus et al. 1980). Use of Se supplements in poultry results in increased levels of Se in liver, kidney, and eggs. Distribution of Se into liver and kidney is much greater than into breast muscle indicating a greater capacity of these organs to accumulate Se. Excretion of Se into eggs results in Se levels equivalent to those in liver and kidney, indicating that eggs are an important route of Se excretion in laying hens (Ort and Latshaw 1978). When Se supplementation stops, the liver, kidney, and egg white and yolk residues decline quickly to control values within 1-2 wk. Breast muscle Se content changes little during supplementation and after withdrawal of supplementation. Oral and parenteral selenium supplementation in swine result in greater accumulation of Se in liver and kidney than in muscle. Oral selenium supplementation also increases the excretion of Se into milk. This method has been used to prevent Se deficiency disease in piglets (Mahan et al. 1975). Oral supplementation with 0.1 ppm Se, as sodium selenate, did not result in levels of Se in blood, meat, or viscera at slaughter (Jenkins and Winter 1973). Despite the large amount of data available on Se residues in food animals, additional information on the pharmacokinetics of parenterally administered Se preparations is needed, especially in sheep and goats which receive parenteral Se supplements. Information on the disappearance kinetics of Se residues in meat and milk is needed for all ruminants. The data currently available in the literature does not allow the calculation of pharmacokinetic parameters of Se in any species. Properly performed pharmacokinetic studies would contribute a great deal towards a better understanding of how food animals utilize supplemental selenium.(ABSTRACT TRUNCATED AT 400 WORDS)