Selenium Requirements in Corn-Soy Diets for Growing-Finishing Swine

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Abstract
Two experiments were conducted to define the minimum dietary selenium (Se) requirements of swine fed corn-soybean meal diets which were low (0.05 ppm) in natural Se and contained 4.2 mg d-α-tocopherol per kilogram. In one experiment, 72 weaned pigs were assigned to eight dietary treatments consisting of (1) basal corn-soy, (2) basal + 0.05 ppm Se (from sodium selenite), (3) basal + 0.1 ppm Se, (4) basal + 0.2 ppm Se and (5–8) dietary treatments 1 through 4 supplemented with 11 IU of vitamin E (E) per kilogram. Sixty-five days before slaughter, all but three pigs on each of treatments 2, 3, 4, 6, 7 and 8 had supplemental Se withdrawn from their diets. The following tissues from both Se withdrawn and not withdrawn groups were analyzed after slaughter (at approximately 100 kg body weight) for Se:whole blood, serum, longissimus muscle, myocardium, liver and kidney. Selenium concentrations increased significantly (P < .05) in longissimus muscle and liver with increasing dietary selenium to the supplemental level of 0.1 ppm (total Se, 0.15 ppm). Myocardium Se was highest with 0.2 ppm supplemental Se, while kidney Se did not increase above that resulting from 0.05 ppm supplemental Se. Se in whole blood, erythrocytes and serum was significantly (P < .01) increased by Se supplements, but there were no differences between supplemental levels. Se withdrawal reduced (P< .01) Se levels in all tissues as compared to those from pigs fed Se to slaughter. Vitamin E supplementation decreased (P < .01) erythrocyte Se concentration and increased (P < .05) kidney Se concentration. The second experiment was concerned with Se absorption and retention from the same dietary Se levels studied in the first experiment as determined by measurement of Se intake and fecal and urinary Se excretion. The effect of a supplement of 22 IU of E/kg was also studied. Se retention was maximized at 0.1 ppm of supplemental Se (total Se, 0.15 ppm). Vitamin E supplementation appeared to increase urinary Se excretion at the supplemental Se level of 0.2 ppm. Based on tissue Se levels and Se retention and excretion patterns, 0.15 ppm Se (0.05 ppm natural, 0.1 ppm from sodium selenite) were required in a corn-soybean meal diet unsupplemented with E. Copyright © 1973. American Society of Animal Science . Copyright 1973 by American Society of Animal Science.

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