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A study was conducted with 24 crossbred boars (77.5 +/- 2.8 days of age) to determine the effects of low Se status on various spermatozoal characteristics and on Se concentration in semen, serum and primary and accessory reproductive tissues. All boars were fed a low Se diet (cornstarch and Torula yeast) ad libitum. Twelve boars were injected every 14 +/- 1 days with sodium selenite (.33 mg Se/kg body weight) and 12 served as saline-treated controls (low Se status). At 210 +/- 5 days of age, six boars in each group were slaughtered, and serum and various tissues were collected and assayed for Se. Treated boars had higher concentrations of Se in the serum (P less than .001), kidney (P less than .001), liver (P less than .001), heart (P less than .001), skeletal muscle (P less than .01), testis (P less than .01), epididymis (P less than .05), seminal vesicle (P less than .01), bulbourethral gland (P less than .001) and prostate (P less than .001) tissues. Starting at 230 +/- 4 days of age, semen samples were collected from the remaining boars at 4- to 6-day intervals until a total of four ejaculates had been obtained from all but two boars. There were no significant treatment differences in semen volume, percentage normal spermatozoa, percentage viability or spermatozoa concentration/milliliter; however, for combined semen Se data, treated boars had more Se than control boars in the whole semen (.165 vs .07 ppm, respectively), spermatozoa (.418 vs .199 micrograms/10(9) spermatozoa, respectively) and seminal plasma (.03 vs .007 ppm, respectively). The boars were castrated around 250 days of age, and no differences in testis length, diameter, weight and spermatozoal concentration were found between groups. Additionally, there were no apparent differences in daily gain, daily feed consumed and the feed to gain ratio between control and treated boars. Although concentrations of Se in serum, semen and reproductive tissues were much lower in control boars than in treated boars, no apparent impairment of sperm morphology or viability resulted from low Se status.
An experiment was conducted to estimate the relative bioavailability of inorganic Se sources based on tissue Se deposition following supplementation at high dietary levels. Twenty-eight crossbred wethers averaging 50 kg initial weight were assigned randomly to seven treatments that were fed for 10 d. The basal diet contained .18 mg/kg Se (DM basis). Dietary Se was added at 0, 3, 6 or 9 mg/kg as reagent grade sodium selenite (Na2SeO3) and 6 mg/kg from either calcium selenite (CaSeO3), Na2SeO3 + fumed amorphous carrier or sodium selenate (Na2SeO4). There were four sheep per treatment group, housed in individual, raised pens with slatted floors. Daily feed intake was restricted to 1,200 g and tap water was available ad libitum. The basal diet was fed for a 10-d adjustment period, then sheep were fed experimental diets for 10 d. At the termination of the experiment, blood samples were taken; sheep were stunned and killed, and livers and kidneys were removed and frozen for Se analysis. There was a linear (P less than .001) uptake of Se in liver, kidney and serum. The CaSeO3 and Na2SeO4 sources resulted in greater (P less than .05) Se concentrations in liver and kidney than did Na2SeO3, but these differences were not significant when the analyzed dietary Se concentrations were used as a covariate in the statistical model. Based on linear and multiple linear regression slopes and average increases in serum, liver and kidney Se concentrations, estimated relative bioavailability values corrected for analyzed dietary concentration, were 100, 101, 90 and 133 for Na2SeO3, CaSeO3, Na2SeO3 + carrier and Na2SeO4, respectively.
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A trial was conducted to determine the effect of maternal supplementation of Se on transfer of Se to the fetus during late gestation. Holstein cows were randomly assigned at dry-off to receive no Se or 3 mg/d of supplemental Se as selenite delivered via an intraruminal bolus. Supplementation significantly increased concentrations of Se in blood of dams at parturition. Similarly, calves of cows that were supplemented with Se had higher Se in blood and liver. Colostral concentrations of Se were increased by maternal Se supplementation; Se increased in the casein fraction. The Se concentrations in blood, plasma, and liver of calves were positively correlated with the Se concentrations in plasma of the dam at parturition. Concentrations of Se in colostrum and in calf liver also were closely correlated. Concentrations of Se in calf liver at d 42 were closely correlated with concentrations of Se in liver at birth. Maternal supplementation of Se increased Se reserves in the liver of the newborn and in colostrum. Carryover effects of Se supplementation of dams were evident in calves at 42 d of age.
The objective of this study was to determine the effects of the amount and chemical form of dietary Se on the distribution of Se among serum proteins. Six growing calves were assigned in a completely randomized design to receive diets containing either adequate (0.41 microgram/g) or excess (0.73 microgram/g) dietary Se. Proteins in serum collected from the calves were separated into albumin, glutathione peroxidase, and selenoprotein P fractions, and the concentration of Se in each was determined. The concentration of Se within serum was elevated by dietary Se supplementation. The selenoprotein P fraction within serum contained the largest percentage of Se among the serum proteins. In a second study, 12 mature cows were assigned to receive one of four experimental salt mixes containing 20, 60, or 120 micrograms of Se as sodium selenite/g of salt mix; the fourth treatment was 60 micrograms of Se as selenized yeast/g of salt mix. Cows given salt with 120 micrograms of Se as selenite or 60 micrograms of Se as selenized yeast had the highest concentrations of Se in whole blood; however, concentrations of Se in serum did not differ among treatments. Concentrations of Se in the protein fractions within serum were not affected by treatment. Within serum, the highest concentration of Se was in the selenoprotein P fraction (31.6 ng/ml), the smallest concentration was in the glutathione peroxidase fraction (4.7 ng/ml), and an intermediate amount of Se was obtained from the albumin fraction (8.5 ng/ml). In conclusion, selenized yeast and selenite as sources of Se for supplementation of cattle resulted in similar patterns of Se distribution among proteins in serum. The greatest concentration of Se was found in the selenoprotein P fraction, which may contribute to Se transportation or function as an antioxidant.
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Day-old poults from hens depleted of Se were fed low-Se basal diets (containing corn, soybean meal, and torula yeast but no added vitamin E) with graded levels of Se supplied by Na2SeO3 or seleno-DL-methionine for 28 and 35 days in Experiments 1 and 2, respectively. Adding .04 ppm Se to the basal diet significantly increased body weight and reduced both the incidence of gizzard myopathy and plasma glutamic-oxaloacetic transaminase (PGOT) activity. Further plasma Se and Se-dependent glutathione peroxidase (SeGSHpx) were elevated by increasing levels of dietary Se. There were no differences in these parameters due to the Se compound fed. Plasma SeGSHpx was significantly correlated with both dietary and plasma Se levels. Poults fed selenomethionine had significantly higher concentrations of Se in the gizzard, breast muscle, and pancreas, but not in the liver and heart, compared to poults fed Na2SeO3. These studies indicate that the utilization of Se in both Na2SeO3 and selenomethionine is approximately equal in young turkey poults.