Maataloustieteellinen Aikakauskirja Vol. 56: 61—72, 1984 Effects of barley-bound organic selenium compared with inorganic selenite on selenium concentration and structure of tissues in pig P. KURKELA and E. KÄÄNTEE Food and Public Health Laboratory SF-61800 KAUHAJOKI, Finland Abstract. A study was made of the effects of barley feeds containing varying levels of natural grain selenium derived from fertilizer and of the effects of sodium selenite on selenium concentrations in the tissues of growing pigs and on the histological structure of myocardium and longissimus muscle. The results indicated that organic grain selenium affects the selenium levels of porcine tissues significantly more than sodium selenite supplementation of the same amount. The organic selenium concentrations of feed and organs were found to be linearly correlated. Spleen, lung and heart were the most reliable indicators of tissue selenium level in pigs. The selenium concentration ofmuscles of pigs fed on naturally seleniferous feed (270 gg Se/kg DM) was at the internationally level (500 gg Se/kg DM in meat), whereas the same amount of selenite in feed increased the selenium level of muscle only slightly (to 200 /ig Se/kg DM). The histological structures of heart and muscle of pigs fed on naturally seleniferous feed were normal, whereas in the selenite group there were signs of muscle dystrophy when the selenium level was below 200 gg Se/kg DM. In addition, the pigs given selenite were subse- quently placed in a lower, fat-containing carcass class. Feed with a natural organic selenium level of 150—200 gg Se/kg DM is preferred to selenite selenium supplement in pork produc- tion. Introduction The low selenium content in Finnish fod- der plants (Oksanen and Sandholm 1970, Kurkela 1982) makes it necessary to add se- lenium compounds to feeds during their pro- duction. Inorganic selenium supplements in feed have not always had the desired effect. Nutritional muscular dystrophy (NMD) has occurred even when the selenium content of the feed has been 0.1 mg Se/kg DM. Selenium-containing fertilizers can also be used to elevate the selenium content of feed. The changes in the selenium contents of Index words: pig, sodium selenite, organic selenium 61 JOURNAL OF AGRICULTURAL SCIENCE IN FINLAND https://www.c-info.fi/en/info/?token=bH4qrofbFZKAoELv.95pofA02Lnw_x2nS99Jnzw.AIWVwmLMig8HYMQOKvYWOTLdLy0cyRCV_fSute7AC0FiqNvvbpAYwlsgh-lBiqFry0Nl7H3sb9zPhcpTZHf2wGpXq7JAF7pClCenoLVJl_A4ux9l8fEhwubB56r9gJyp2YWtGZ93z47IJfExwDYejgsilOC95FxbYiCEo3BO546ZPkCbm496L1eqZdzvWOw-Xg animal tissues resulting from the use of these fertilizers for growing feed grain should be investigated and the effects of elevated tissue selenium contents examined from the point of foodstuffs hygiene. The object of the present study was to in- vestigate the effects of feed with varying levels of organic and inorganic selenium on health organ selenium content macroscopic and histological structure of the muscles in the pig. Materials and methods Animals Twenty-five Yorkshire pigs with an initial weight of 25 ± 0.5 kg were used in this study. They were divided into four groups (6 + 6 + 7 + 6). Each group received the test feed shown in Table 1 over a period of 110 days. In addition, samples for comparison were taken from the slaughterhouse from healthy pigs and from pigs with NMD. Feed and feeding Kemira Oy had grown barley with dif- ferent selenium levels by fertilizing it one month after sowing with 0 to 1.0 kg sodium selenite per hectare (Korkman 1980). The feeds were mixtured from these barleys and protein mineral concentrate containing 40 % raw protein and 18.5 °7o minerals (Table 2) and from sodium selenite (Table 1). All the feeds used in the trial contained 30 HJ/kg of vitamin E. All animals were given the group 1 feed for the four weeks leading up to the trial. Table 2. Feed concentrate Fish meal 30 % Meat & bone meal 8 Soya 24 Fodder yeast 9 Wheat bran 5 Pig vitamin 3 Ground chalk 5 Fodder phosphate 4 NaCl 2.5 Lignox 4 Molasses 1 15 % of this concentrate was mixed with barley in con- nection with grinding. The pigs were kept in sties with concrete floors. They obtained test feed and water freely from automatic dispensers. Follow-up The animals were examined clinically once a week. They were slaughtered after 110 days. The carcasses were examined visually at the time the meat was inspected and classi- fied in the slaughterhouse. Samples Blood and faeces samples were taken at the end of the trial. Samples of urineand bile were taken after slaughtering, together with tissue samples from the spleen, liver, muscle (dorsal longissimus muscle), lung, kidney, pancreas, brain, CNS, eye and coccyx. The tissue samples were taken by cutting a sagit- tal or otherwise representative sample from the organ or from one of its lobes. A sample Table I. Selenium concentrations of experimental feeds Trial Feed (grain Se cone.) Total feed group Se concentration jig/kg DM I Barley 10/ig/kg DM + 15 % feed concentrate 100 II Barley 10 /ig/kg DM + 15 % feed concentrate + Na2SeO, 270 111 Barley 180 DM + 15 % feed concentrate 270 IV Barley 680 DM + 15 % feed concentrate 700 62 of myocardium was taken from the papillary muscle and the left ventricle wall. Samples from equal-sized control pigs of the same strain from the same slaughter- house used as random sample material were taken from the longissimus muscle and the myocardium both from clinically healthy animals and from those with nutritional muscular dystrophy (NMD). The samples were frozen immediately and kept at —2O°C until analysed. Histological samples from the muscle, myocardium, liver and kidney were stored in 10 % formalin. Chemical analysis and histological examination The method employed in the selenium determination was Saari and Paaso’s (1980) modification of the hydride method coupled with atomic absorption spectrophotometry. The lowest measurable selenium content by this method is 10 fig Se/kg. Statistical analysis The following methods were used in the statistical analysis of the results: The differences in tissue trace element contents between the feed groups were tested for homogeneity of variances by Bartlett’s test, differences between means by one-way variance analysis and significantly different means were discriminated by Tukey’s test. the dependence of tissue selenium level on feed selenium level was tested by linear regression analysis with feed selenium con- tent as the systematic variable. Both the loga- rithmic function and the linear model were tested in the analysis. The correlations between the Se-levels of different organs were calculated using a correlation coefficient. Quality classification of the carcases and slaughtering weights were tested using Fischer’s accurate four-field test, one-way variance analysis and Tukey’s test. Results The test pigs were clinically healthy during the tests. The mean slaughtering weights in the different groups are shown in Figure 1. No statistical differences were found in these. In the quality classification, five pigs out of six in Group II were found to be fatty and were placed in class I—. The rest of the pigs were classified as belonging to class I (Figure 1). The mean selenium contents of samples taken from test animals are shown in Table 3. It was found that sodium selenite supple- ment in the basic feed (270 Se/kg DM) in Group II did not statistically significantly elevate the selenium content of the muscle and other organs, whereas a corresponding selenium supplement in organic form (Group III) resulted in a statistically significant in- crease. In the muscle this difference in the elevation of the selenium contents was about 250 %. The change in the organ selenium contents in Groups I, II and IV was linear. The depen- dence of muscle seleniumcontent on the level Fig. I. Mean carcass weight and quality class 63 of organic selenium in the feed is described by a curve of the second degree equation (Figure 3). In the test groups, the selenium content of blood correlated best with the selenium con- tents of the myocardium, liver, CNS and bile (0.998 < r < 1). Blood selenium content was only indicative of the selenium content of muscle. The most reliable indicator organs of the body selenium content were found to be Fig. 2. Selenium content of muscle (M. longissimus dorsi) and associated selenium content in diet 64 5 Table 3. Tissue selenium contents in test pigs (gg/kg DM, mean ± SD) Trial group Trial Tissue j U m ,v Blood 550 + 64 566 + 47 614 + 63 1341+929 Spleen 1041 ±93 1125±l2l 1371 + 116 2200±360 Bone 141 ±34 191 ±34 414±115 541 ±263 Muscle 133 ±23 200±28 500±70 1016+134 Heart 683 ±23 733 ±l3l 1057 ±156 2550±l5O Liver 1333 ±75 1617±227 1757±267 3433±320 Lung 691 ±53 766±79 950±96 1716±60 Kidney 5183 ±494 5666±1020 6128±832 8550 + 495 Pancreas 975 ±25 1325 ±375 Brain 400 ±6B 433 ±23 707 ±B6 1450±l5O Spinal cord 136 ±l9 191 ±34 228 ±52 675 + 85 Eye 233 ±23 291 ±34 457 ±72 708 ±156 Bile, Combined sample 100 100 150 450 Urine, Combined sample 150 2100 1300 4700 Faeces, Combined sample 500 1800 750 1700 the spleen and the lung, followed by the heart and the brain (Table 4). The selenium content of the meat of clini- cally healthy pigs taken from the slaughter- house and used as control samples was 150 fig Se/kg DM, and that of pigs with clinical signs of muscular dystrophy 378 ± 79 fig Se/kg DM. The corresponding seleniumcon- tents of the myocardium in clinically healthy pigs were 600 fig Se/kg DM and in pigs with Fig. 3. Organic selenium in diet and associated selenium content of longissimus muscle of pig 65 Table 4. The correlation matrix of selenium in the tissues examined. Blood Spleen Bone Muscle Myo- Lung Kidney Liver Brain Spinal Eyes Bile Urine Faeces cardium cord Blood Spleen * Bone 0 0 Muscle 0 * * Myocardium ** ** 0 Lung * *** 0 * ** Kidney * »* 0 * * ** I iyer ** ** 0 * ** ** ** Brain * *** 0 ** ** ** ** ** Spinal cord ** * 0 * ** ** ** ** * £ye 0 * ******* ** ** ** Q gj]p ** ** 0 * *** ** * ** * ** Q Urine 00 000 00000 00 Faeces 00 000 00000 000 nutritional muscular dystrophy 641 ± 159/tg Se/kg DM, i.e. no statistically significant differences were found. The mean selenium content of the meat of pigs with clinical muscular dystrophy was 378 n g Se/kg DM, which deviated greatly from the corresponding means in Groups I, II and IV, while the mean selenium content of the myocardium, 641 /ig Se/kg DM, dif- fered significantly from the mean selenium contents of Groups 111 and IV. High biliary selenium contents were found in Groups 111 and IV, whereas in Group II it was the selenium content of the urine and faeces that was high. The biliary selenium contents were in agreement with the blood selenium contents and correlated significant- ly with the selenium contents of the myocar- dium and other internal organs. Macroscopically, no changes were observ- ed in the meat or organs of the test animals. Histologically in Groups I and II incipient degradation of the the myofibres was often seen in the longissimus muscle and the myo- cardium, as characterized by swelling of the myofibrils, absence of the sarcoplasm and myolysis. The myocardium showed loss of cross-striation and segmentation of myo- fibres (Figures 4,5, 6). O = no significant correlation * = almost significant correlation at 95 % certainty ** = significant correlation at 99 % certainty *** = highly significant correlation at 99.9 % certainty Corresponding correlation coefficients (r) r = 0.950 0.950 r = 0.991 0.991 r = 0.998 0.998 r = 1 66 67 Fig. 4. Normal muscle, Se level over 200 gg Se/kg Dm Fig. 5. Incipient muscular dystrophy (NMD), Se level 150—200 /ig/Se/kg DM Similar changes due to nutritional mus- cular dystrophy were also found in clinically healthy pigs in the control group. The samples from Groups 111 and IV did not show any histological changes. These degenerative muscular and myocar- dial changes were manifested progressively with increasing severity when the muscular selenium content fell to 200—150 /xg Se/kg DM or below. In pigs with clinical nutrition- al muscular dystrophy, these histological changes were found in all samples of the longissimus muscle in which the selenium content was 200—450 /xg Se/kg DM. Progressively increasing degradation chan- ges were observed in the myocardium of the pigs in Groups I and II and of the clinically healthy control animals when the myocar- dium selenium content fell to 600—700 /xg Se/kg DM or below. The selenium content of the myocardium of pigs with clinical nutri- tional muscular dystrophy was 600—850 /xg Se/kg DM. Discussion The clinical condition of the test animals was good during the trial. The selenium con- tents used did not adversely affect the health of thepigs. This was as expected, because the selenium contents of the test feeds were clearly between the selenium contents causing defi- ciency states (50 /xg Se/kg DM) reported by Latshaw et al. (1977), and the content found to be toxic in pigs (5000) /xg Se/kg DM). The selenium content of the feed given to Groups II and 111, 270 /xg Se/kg DM, was of the same order as the mean natural selenium content of feed grain grown in the selenium-rich area of the USA (Kubota et al. 1967). The different feeds used resulted in dif- ferent selenium contents in the pig tissues. In Group I and in the healthy control group the selenium contents were 133 ± 23 /xg Se/kg DM and 150 /xg Se/kg DM, corresponding to the selenium content of Finnish pork report- ed by Nuurtamo et al. (1980), which in turn is lower than the selenium contents of foreign Fig. 6. Muscular dystrophy (NMD), Se level under 150 ng Se/kg DM 68 pork, 450—1890 fig Se/kg DM (Lindberg 1968, Morris and Levander 1970, Ku et al. 1972, Norrman 1977). In Group II (feed containing 270 fig Se/kg DM as sodium selenite) the selenium content of the pork was 200 ng Se/kg DM. The eleva- tion is small although the selenium content of the feed was three times greater than in Group I. In Group 111, in which the feed con- tained the same amount of organic selenium of cereal origin, the selenium content of the muscle rose to 500 fig Se/kg DM and in Group IV to 1000 fig Se/kg DM. The sele- nium level in the muscles was closely related to the organic dietary Se levels the pig re- ceived (p < 0.001). The differences could also be seen in tissue selenium determinations in different organs: the difference between the biological effect of sodium selenite and organic selenium of cereal origin is shown in the selenium con- tents of Groups II and 111. The different che- mical compounds of selenium, organic and inorganic, have different metabolic pathways in the organism (Cary et al. 1973). Selenomethionine and selenocysteine are bio- logically very active in pig (Ku et al. 1972). In plants such as wheat and barley, most of the selenium is incorporated into protein as selenomethionine (Olson et al. 1970). In fish meal, selenium is known to be present as se- lenocysteine, the bioavailability of which has been found to be lower than that of seleno- methionine. Monogastric mammals cannot incorporate selenite selenium directly into cysteine or methionine, although the bacteria of intestinal tract, e.g. E. coli, can synthesize organosele- nium compounds from selenite, which may explain the conversion of Se to nonlabile re- duced forms in vivo (Allaway 1973). The selenium bound in wheat or barley in the form of selenomethionine has a better bioavailability than the same quantity of se- lenium bound in meat or fish meal as seleno- cysteine (Ku et al. 1972). This is probably one reason for the low selenium content of Finnish pork, since the selenium content of Finnish feed grain is low, 5—20 fig Se/kg DM, and the pig feed mixtures used contain meat and fish meal as the source of protein. In the USA, soya is usually used instead of these (Ku et al. 1972). It seemed that selenite selenium, seleno- methionine and seleniferous plants (non ac- cumulator species) may follow different me- tabolic pathways leading to differences in tis- sue concentrations of selenium, even though all these forms of Se are about equally effec- tive in preventing selenium response diseases (Cary et al. 1973, Jaakkola et al. 1982). Variance analysis showed the selenium levels in the blood samples to be highly signi- ficantly dependent (p 8 0.001) on the feed se- lenium content, but in the regression analysis the dependence of blood selenium level on feed selenium content was only suggestive (90 %, regression coefficient 1.4). Contrary to the results obtained with chickens (Kään- tee and Kurkela 1980), blood was not among the most reliable tissue indicators of body selenium content in the pig. The spleen, lungs, heart and brain were more reliable. The selenium contents of all these tissues rose quite high due to organic selenium in the feed. In all test groups, the mean selenium con- tents of the organs were the highest in the kidneys, varying between 5200 and 8600 fig Se/kg DM; the next highest contents were in the liver, 1100—3500 fig Se/kg DM, myocar- dium, 680—2550 fig Se/kg DM, spleen, 1000—2200 fig Se/kg DM and brain 400— 1450fig Se/kg DM. The lowest seleniumcon- tent was found in the spinal cord, eye and bone. The greatest differences in the sele- nium contents between different test groups were found in the heart, liver, brain, spinal cord and bone. The low selenium content of Finnish feeds is compensated during manufacture by the addition of sodium selenite, which has a low biological availability. This is shown by the incidence of histologically verified nutri- tional muscular dystrophy in Groups 1 and 11, but also in healthy and unhealthy animals 69 from the slaughterhouse. High selenium con- tents were found in both the muscle and myo- cardium of these unhealthy animals. This may be due either to the selenium administered to the animals in the form of medication or to mobilization of selenium from the body to the diseased areas (Toikka 1978). The statistical results obtained indicate (Figure 3) that to produce histologically healthy pork with a selenium content of more than 200 fig Se/kg DM, the content of organic selenium in the feed must be over 130 fig Se/kg DM. Since neither the international selenium content of pork nor even the selenium level required for production of histopathologi- cally healthy meat is obtained by the addition of sodium selenite, even up to 270 fig Se/kg DM, the study supports the idea that the only way to elevate the selenium content of Fin- nish pork to the international standard is to raise the organic selenium content of pork feed to at least 150—200 fig Se/kg DM (i.e. 0.15—0.2 ppm). This can be done safely by fertilizing the feed grain by selenium-con- taining fertilizers or by foliar spraying with solutions containing selenium (Korkman 1980). Considering the selenium levels in Table 2, and the average pork consumption of about 71 grammes per person per day in Finland (Nuurtamo et al. 1980) the range selenium per pig diet studied in the present investiga- tion accounts for a difference of not more than 3—25 fig selenium in the average daily intake in man. This 3—25 fig is insignificant compared with the toxic level of 2400—3000 fig selenium per day previously stated (NRC 1976), although it is of greater importance in terms of the proposed daily adequate amount of 50—200 fig (NBH Circular No. 1762/1981). The toxic level could be exceed- ed with a daily consumption of more than about 1.1 kg pig kidney or more than about 2.1 to 2.6 kg liver, from pigs whose diet con- tains between 100 and 700 fig Se/kg DM (0.1—0.7 ppm). Summary An investigation was made into the effects of barley feeds with varying levels of natural organic selenium introduced by means of selenium-containing fertilizer and of inor- ganic sodium selenite on the concentrations of selenium in the tissues of growing pigs (blood, spleen, bone, muscle, heart, liver, lung, kidney, pancreas, brain, spinal cord and eye), and on the histological structure of myocardium and longissimus muscle. The results indicated that natural organic grain selenium affects the selenium levels of tissues in pig significantly more (muscle 250 *7o) than sodium selenite supplementa- tion of the same amount. The natural sele- nium concentrations of feed and organs were linearly correlated. Spleen, lung and heart were the most reliable indicators of tissue selenium levels in pigs. When the feed selenium level was supple- mented to 100 fig Se/kg DM (0.1 ppm) with sodium selenite, the selenium concentration of longissimus muscle was 133 ± 23 fig Se/kg DM. The selenium concentrations of muscles of pigs fed on naturally seleniferous feed, 270 fig Se/kg DM were at the normal interna- tional level (500 fig Se/kg DM in meat), whereas the same feed selenite selenium, 270 fig Se/kg DM, increased the selenium level of muscles only slightly (to 200 fig Se/kg DM). The histological structures of heart and striated muscles of the pigs fed on 270 fig Se/kg DM organic selenium feed were normal and healthy, whereas in the group given the same amount of selenite there were histologi- cal signs of muscle dystrophy (NMD). A grain selenium concentration of 700 fig Se/kg DM did not have any adverse effect on ex- perimental animals. In the quality classification of the car- casses, 5/6 pigs in the group receiving so- dium selenite were placed in Class I- because of their high fat content. The study supports the idea that natural organic selenium of grain origin of 150— 70 200 /xg Se/kg DM (0.15—02 ppm) is the most both as regards the health of the animals and suitable for pork production and more effec- the elevation of the selenium content to the live than selenite-induced selenium content normal international level. References Allaway, W.H. 1973. Selenium in the food chain. Cor- nell Vet. 63, 151 170. Anon 1976. National Research Council (NRC). Sele- nium and human health. Nutr. Rev. 43, 347—348. Cary, E.E., Allaway, W.H. and Miller, M. 1973. Uti- lization of different forms of dietary selenium. J. Anim. Sci. 36, 285—292. Jaakkola, K., Tummavuori, j„ Kurkela, P., Tolonen, M., Pirilä, A. and Arstila, A. 1982. Orgaanisen ja epäorgaanisen seleenin imeytyminen vereen terveillä suomalaisilla miehillä. (Absorption of organic and inorganic selenium in healthy Finnish men). Ympäris- tö ja Terveys, 5. Korkman, J. 1980. The effect of selenium fertilizers on the selenium content of barley, spring wheat and po- tatoes. J. Sc. Agr. Soc. Finl. 52, 495—504. Ku. P., Ely. W., Groce. A. and Ullrey, D. 1972. Natural dietary selenium, -tocopherol and effect on tissue selenium. J. of Anim. Sc. 34, 2, 208—211. Kubota, J., Allaway. W., Carter, D., Cary. E. and Lanzar, V. 1967. Selenium in crops in United States in relation to selenium-responsive diseases ofanimals. J. Agr. Food. Chem. 15, 448. Kurkela, P. 1982. Seleeni biologiassa ja lääketieteessä (Selenium in Biology and Medicine). Ympäristö ja Terveys 1, 3—36. Kääntee. E. and Kurkela. P. 1980. Comparative effects of barley feed and sodium selenite on selenium levels in hen eggs and tissues. J. Scient. Agric. Soc. Finl. 4, 357—367. Latshaw, J., Ort, J. and Diesem, L. 1977. The selenium requirements of hen and effects of deficiency. Poult. Sci. 56, 1876—81. Lindberg, P. 1968. Selenium determination in plant and animal material and in water. Acta Vet. Scand. Suppl. 23, 1—43. Morris, V. and Levander, O. 1970. Selenium content of foods. J. Nutr. 100, 1383—1388. Norrman, E. 1977. Selenbrist. Vär Näring 12, 6—7. Nuurtamo, M., Varo, P., Saari, E. and Koivistoinen, P. 1980. Mineral Elements Composition of Finnish Foods, V Meat and Meat Products. Acta Agr. Scand. Suppl. 22, 57—76. Oksanen, H. and Sandholm, M. 1970. The selenium content of Finnish forage crops. J. Sci. Agr. Soc. Finl. 42, 251—254. Olson, 0.E., Novacek, E.J., Whitehead, E.J. and Pal- mer. I.S. 1970. Selenium in wheat. Phytochem. 9, 1181—1188. Saari, E. and Paaso, A. 1980. Mineral Element Com- position of Finnish Foods, 11 Analytical Methods. Acta Agr. Scand, Suppl. 22, 15 —25. Toikka, M. 1978. Public Lecture at the University of Helsinki. Ms received February 7, 1984 71 SELOSTUS Ohran orgaanisen seleenin ja epäorgaanisen seleniitin vaikutuksista sian elimistön seleenipitoisuuksiin ja lihaksiston rakenteeseen. P. Kurkela & E. Kääntee Kauhajoen elintarvikelaboratorio 61800 Kauhajoki Tutkimuksessa tarkastellaan ohran seleenin ja epäor- gaanisen seleniitin vaikutuksia kasvavien sikojen elimis- tön seleenipitoisuuksiin sekä sydänlihaksen ja selkäli- hasten histologiseen rakenteeseen. Tutkimuksiin käytettiin 25 sikaa jaettuna neljään ryh- mään sekä vertailuaineistona terveitä ja lihasrappeumaa sairastavia teurassikoja teurastamosta. Koeryhmiä ruo- kittiin 110 vrk:n ajan rehuilla joiden Se pitoisuudet oli- vat 100 —7OO ng/kg. Tulokset osoittivat että viljan orgaaninen seleeni ko- hotti porsaiden elimistön Se pitoisuutta huomattavasti enemmän kuin vastaava määrä natriumseleniittiä. Re- hun seleenin ollessa viljaperäistä, 270 /rg/kg, kohosi li- han Se pitoisuus tasolle 500 jtg/kg kuiva-ainetta, rehun seleenin ollessa natriumseleniittiä, 270 ng/kg, oli lihan Se pitoisuus vain 200 #rg/kg kuiva-ainetta. Porsaan elimistön Se tason parhaat ja luotettavimmat indikaattorit olivat pernan keuhkojen ja sydämen Se pi- toisuudet. Histologisesti todettiin ohraseleeniä saaneiden porsai- den lihakset ja sydämet terveiksi, kun taas seleniitti- porsailla lihasten Se pitoisuuden alittaessa 200 w?/kg kuiva-ainetta ilmeni lihasrappeumaa. Tulokset osoittivat ohraan sidotun seleenin kohotta- van elimistön Se tasoa enemmän kuin vastaavat määrät natriumseleniittiä ja suojaavan elimistöä paremmin li- hasrappeumalta. 72