Vet. Med. Czech, 49, 2004 (5):

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1 Originl Pper Influence of prenterl dministrtion of selenium nd vitmin E during pregnncy on selected metolic prmeters nd colostrum qulity in diry cows t prturition L. P, J. P, J. F, A. P Clinic of Diseses of Ruminnts, Fculty of Veterinry Medicine, University of Veterinry nd Phrmceuticl Sciences, Brno, Czech Repulic ABSTRACT: The im of the present work ws to study the influence of different dose of prenterl dministrtion selenium nd vitmin E in diry cows prior to prturition on selected metolic prmeters nd colostrum qulity. A totl of 19 diry cows from frm with selenium deficiency were included in the study. The cows were divided in 3 groups (C, E1, nd E2). In group E1 product contining selenium nd vitmin E (Selevit inj..u.v.) ws dministered IM four weeks prior to the expected dte of prturition. In group E2 the sme product ws dministered twice, eight nd four weeks prior to prturition. Group C consisted of control nimls to which no product ws dministered. On the dy of prturition smples of lood nd first colostrum were collected for lortory exmintion. Concentrtions of selenium were determined in lood nd tht of vitmin E, thyroid hormones (T3 nd T4) nd ctivities of enzymes detecting musculr dmge (CK, AST, LD) were determined in serum. Colostrum ws nlysed to determine the concentrtions of selenium, vitmin E, immunogloulins, s well s to determine its density. The occurrence of the disese during the first month er prturition ws evluted in ll groups. Higher concentrtions of selenium nd vitmin E were found in the smples (experimentl groups E1 nd E2) collected on the dy of prturition. Group E2 showed significntly (P < 0.05) higher T3 concentrtion compred to groups C nd E1 (3.05 ± 0.42 nmol/l vs 1.88 ± 0.71 nd 1.81 ± 0.30 nmol/l, respectively). The sme p ern ws confirmed for immunogloulins concentrtions in colostrum (34.08 ± 5.93 U ZST vs ± 5.41 nd ± 8.33 U ZST, respectively). Compred to group C, cows in group E2 lso showed significntly (P < 0.05) higher concentrtions of selenium in colostrum (45.43 ± vs ± 8.42 µg/l). The dministrtion of selenium nd vitmin E did not influence other prmeters evluted in the study. During the first 30 dys of the postprtum period trend of lower occurrence of mstitis ws oserved in group E2 compred to oth group C nd E1 (no cse of mstitis compred to 5 nd 4 cses of treted mstitis, respectively). Keywords: c le; immunogloulins; thyroid hormones; T3; mstitis Selenium is present in ll tissues of the orgnism. Physiologicl functions of selenium re medited in prticulr y selenoproteins (Underwood nd Suttle, 1999). Glutthione peroxidses (GSH-Px 1-4) elong mong the most importnt selenoproteins, whose min function coincides with their ntioxidtive effect. Iodothyronine deiodinse is nother importnt selenoprotein. This enzyme regultes thyroxine (T4) conversion to iologiclly ctive 3,3,5-triiodothyronine (T3) or to reverse triiodothyronine (rt3). The ltter represents thyroid hormone in n inctive form. The following sustnces elong mong other known selenoproteins: thioredoxin reductses, selenoproteins P, W, R, T, N, selenium inding proteins (58, 56 nd 14 kd), sperm cpsule selenoprotein, rt prostte glnd glndulr epithelil cells protein, nd others (Arthur et l., 1990; Lrsen nd Berry, 1995; Fuchs, 1996; Kohrle, 2000; Zimmermnn nd Kohrle, 2002; Birringer et l., 2002). Supported y the Ministry of Eduction, Youth nd Sports of the Czech Repulic (Grnt No nd FRVS No. 341/2002). 149

2 Originl Pper Vet. Med. Czech, 49, 2004 (5): Insufficient selenium intke y the orgnism is mnifested y numerous iochemicl chnges, such s reduced selenium concentrtion nd GSH-Px ctivity in lood nd tissues, nd incresed ctivity of cretine kinse (CK), sprtte minotrnsferse (AST) nd lctte dehydrogense (LD) in serum due to musculr dmge, incresed production of rective forms of oxygen nd finl products of lipoperoxidtion in lood nd tissues (mlonyl dildehyde, thiorituric cid rective sustnces (TBARS, F 2 -isoprostnes), s well s other possile secondry chnges like shi in T3 : T4 rtio (Underwood nd Su le, 1999). Biologicl functions of selenium re complemented y vitmin E, which lso shows the effects of cellulr ntioxidnt. Therefore some clinicl mnifesttions of hypovitminosis E nd selenium deficiency re very similr. Therpy nd prophylxis of these disorders usully consist of the dministrtion of oth sustnces together (Smith, 1996; Smith et l., 1997; Weiss, 1998; Allison nd Lven, 2000). Deficiencies of selenium nd vitmin E re frequently dignosed lso in the Czech Repulic (Pvlt et l., 1999, 2002), which requires tretment y dministrtion of products contining selenium nd vitmin E (Pvlt et l., 1999, 2001, 2002). The im of the present work ws to study selected metolic prmeters nd colostrum qulity er the dministrtion of such product to diry cows in the finl period of pregnncy. MATERIAL AND METHODS This work goes out from prt of n experiment relised in frmework of n investigtion of selenium metolism in the mternl trnsfer of selenium to neworn clves (Pvlt et l., 2003). The method in this work is expnded nd results re evluted from the wiev of n influence of selenium nd vitmin E on selected metolic prmeters, colostrum qulity nd stte of helth. Description of frm nd nimls The study ws crried out on diry frm FADOM t Dolni Mesto, district Hvlickuv Brod, Czech Repulic in utumn. The herd consisted of Red-nd-White diry cows (Czech Red-nd-White dul purpose reed crossed with Red Holsteins up to 80%). Totl cpcity of the frm ws 400 nimls. Selenium deficiency ws repetedly dignosed in this herd. The lst exmintion prior to strt of the study reveled men selenium concentrtion in whole lood of 45.3 ± 10.7 µg/l in 8 cows from the group of lte pregnnt nimls. Incresed occurrence of mstitis ws lso detected in the herd (862 treted cses during the lst yer). The sme pplies to retined plcent (13% of ll cows tht clved during the yer) nd metritis (18.5% of ll cows tht clved during the yer). Isolted cses of clinicl forms of nutritionl musculr dystrophy were found in clves (10 cses during the lst yer). The nimls were kept in free housing system with seprte clving rn nd equipped with individul oxes with edding. The cows were divided in groups ccording to the lcttion nd reproduction stge. A totl mixed rtion (TMR) wgon ws used for feeding the nimls. The rtion of dry cows included in the study consisted of 15 kg of preserved forge (5 kg of mize silge, 10 kg of grss hylge) nd 4 kg of medow hy. Three weeks prior to the expected prturition grin mixture in the quntity of 3.5 kg per niml (whet, rley, extrcted soy mel, rpeseed cke, limestone, slt) ws dded to the feed. In totl 19 nimls (ged yers) in the finl period of pregnncy were included in the study. On the sme dy the nimls were rndomly divided in 3 groups: C control group of 5 nimls to which no product contining selenium nd vitmin E ws dministered prior to prturition; E1 experimentl group of 7 nimls to which the injectle product Selevit inj..u.v (sodium selenite 2.2 mg, lph tocopherol cette 25 mg in 1 ml of the solution) ws dministered once during the dry period (4 weeks prior to expected prturition) in the dose recommended y mnufcturer, i.e. 20 ml IM (44 mg of sodium selenite nd 500 mg of lph tocopherol cette); E2 experimentl group of 7 nimls to which the injectle product Selevit inj..u.v ws dministered twice during the dry period (8 nd 4 weeks prior to expected prturition), i.e. in the totl dose of 88 mg of sodium selenite nd mg of lph tocopherol cette. Collection of smples nd lortory exmintion Blood smples from ll the cows were collected on the dy of prturition. First colostrum ws lso collected. 150

3 Originl Pper The following vlues were mesured in the smples: whole lood treted with heprin selenium; lood serum ctivity of AST, CK, LD, concentrtion of vitmin E, T3, T4; colostrum density, content of immunogloulins (IG), concentrtion of selenium nd vitmin E. The method of selenium determintion consisted of the following steps: smples of whole heprinised lood nd colostrum were minerlised in closed system using microwve (Milestone MLS 1200) digestion technique with HNO 3 nd H 2 O 2. Smples were evported nd the minerl residue ws dissolved in wter to which 20% HCl ws dded. Selenium ws then determined y Unicm 939 AA Spectrometer using hydride AAS technique. Ctlytic ctivity of AST nd LD ws determined y n utomtic nlyser Cos Mir using stndrdised photometric methods with BioVendor sets ( L AST ctlogue No , nd L LDH ctlogue No ). Ctlytic ctivity of CK ws determined using the sme mchine nd the set Kretinkins NAC 105 (Lchem.s.). Vitmin E (lph tocopherol) ws determined y fluorometry ccording to Boud et l. (1980) using fluorescence spectrophotometer 204 Perkin- Elmer. Thyroid hormones were determined using Immulite mchine y mens of chemiluminiscence sets y BioVendor (Totl T3 LKT 31 nd Totl T4 LKT 41). Colostrum density ws mesured y densimeter (colostrometer). Immunogloulins were determined y mens of zinc sulfte turidity rection (Slnin et l., 1976) er removl of csein y rennet cogultion (Dolezlov, 1978). Assessment of helth disorders An ssessment of the occurrence of clinicl forms of diseses ws done in the nimls of different groups. Cses which required tretment during the first 30 dys of the postprtum period were included in the ssessment. Sttisticl methods Bsic sttisticl prmeters of results (mens, stndrd devitions) in individul groups, nd comprison etween results of groups (using the Student s t-test er F-test for equlity of vritions) were computed using Microso Excel 97. RESULTS AND DISCUSSION In experimentl groups (E1 nd E2) higher selenium concentrtions were found in comprison to control group (C) on the dy of prturition (Tle 1). Men selenium concentrtions in whole lood in ll groups were fr elow the recommended vlue of 100 µg/l (Vn Sun, 1990; Pvlt et l., 2000). In cows of group E2 the difference ws significnt (P < 0.05). Tle 1 furthermore shows tht significntly higher vitmin E concentrtion ws found in cows in group E2 compred to oth control group nd group E1 (P < 0.05). Men vitmin E concentrtion in serum in ll groups were round the minimum recommended vlue of 8.12 µmol/l (Jgos et l., 1981). The results showed tht repeted dministrtion of Selevit inj..u.v. to pregnnt cows ws eneficil, lthough the deficiency in lood ws not completely compensted. Improved intke of selenium nd vitmin E is importnt for diry cows ecuse of positive effect of these sustnces in prophylxis of mny helth disorders, which frequently occur in cows, nd clves lredy in the erly postprtum period. Such disorders consist of nutritionl musculr dystrophy, reproductive disorders (retined plcent, incresed incidence of endometritis nd ovrin cysts), incresed somtic cell count, higher Tle 1. Effect of prenterl dministrtion of selenium nd vitmin E on lood prmeters of cows (C control group, E1 nd E2 tretment groups) t prturition Se whole lood (µg/l) Vit. E serum (µmol/l) T3 serum (nmol/l) T4 serum (nmol/l) C Men ± SD ± ± ± ± E1 Men ± SD ± ± ± ± 8.58 E2 Men ± SD ± ± ± ± :; : P < 0.05) 151

4 Originl Pper Vet. Med. Czech, 49, 2004 (5): occurrence of clinicl forms of mstitis, immunity disorders, frequent occurrence of respirtory nd gstrointestinl infections in clves, disorders of thermoregultion in clves orn in cold wether, etc. (Brzezinsk-Sleodzinsk et l., 1994; Crtens, 1994; McDowell et l., 1996; Smith, 1996, Smith et l., 1997; Weiss, 1998; Underwood nd Su le, 1999; Allison nd Lven, 2000). The exmintion of thyroid hormones reveled tht in cows injected with selenium nd vitmin E 4 nd 8 weeks prior to prturition hd higher T3 concentrtions t prturition (P < 0.05) thn cows injected 4 weeks prior to prturition or control cows (Tle 1). The difference cn e proly explined y n incresed ctivity of iodothyronine deiodinse, which prticiptes in the conversion of T4 into ctive T3 nd which ctivity is influenced y selenium (Arthur et l., 1990; Lrsen nd Berry, 1995; Kohrle, 2000). Similr results confirming positive effect of selenium on T3 concentrtions were presented for instnce y Wichtel et l. (1994) nd Awdeh et l. (1998), who oserved incresed T3 concentrtions in cows nd clves er higher selenium intke. The rtio of T3 : T4 clculted in our work ( ) is close to the results of the previously mentioned uthors ( ). It cn e therefore concluded from our oservtions tht fter repeted dministrtion of product contining the comintion of selenium nd vitmin E during the period prior to prturition positive effect of incresed selenium intke on higher T3 concentrtions nd higher T3 : T4 rtio ws confirmed. No conclusive reltion ws found etween the ctivity of enzymes detecting musculr dmge nd the intke of selenium nd vitmin E. Men ctivities of the enzymes in lood serum in different groups of cows were slightly incresed (AST µkt/l; CK µkt/l, nd LD to µkt/l) over the reference limits for helthy nimls (AST < 1.41; CK < 0.60; LD < µkt/l) (Vrzgul nd Sokol, 1990; Pechov, 1992). However, there were no significnt differences mong the groups. Higher increse in CK ctivity compred to the vlues of AST nd LD my e riuted to the fct tht smples were collected on the dy of prturition when the cows were stressed to different extent nd certin musculr dmge my occur. Oviously low intke of selenium nd vitmin E my predispose to musculr dmge (Pvlt et l., 2001). Colostrum exmintion reveled trend towrds higher selenium concentrtions in cows er the dministrtion of Selevit inj..u.v. (Figure 1). Men selenium concentrtion found in group E2 (45.43 ± µg/l) is significntly (P < 0.05) higher thn in control group (29.29 ± 8.42 µg/l). Figure 2 shows tht er the dministrtion of Selevit inj..u.v. the confirmed higher concentrtion of vitmin E in lood of cows did not led to corresponding increse in colostrum. On the contrry, in cows of group E2, where the concentrtion of vitmin E ws the highest, lowest levels of this vitmin were found in colostrum. No reltion etween the concentrtion of vitmin E in serum of the dm nd its concenttion in colostrum ws determined. Sufficient intke of vitmin E through colostrum is extremely importnt for neworn ruminnts, ecuse ft-solule vitmins re trnsported only in limited degree 60 lood colostrum 30 lood colostrum Figure 1. Concentrtion of selenium (µg/l) in whole lood nd colostrum of cows (C control group, E1 nd E2 tretment groups) t prturition :; : P < 0.05 Figure 2. Concentrtion of vitmin E (µmol/l) in serum nd colostrum of cows (C control group, E1 nd E2 tretment groups) t prturition :; : P <

5 Originl Pper Figure 3. Colostrum density (kg/m 3 ) of cows (C control group, E1 nd E2 tretment groups) t prturition Figure 4. Effect of prenterl dministrtion of selenium nd vitmin E on content of immunogloulins (U ZST) in colostrum of cows (C control group, E1 nd E2 tretment groups) t prturition :; : P < 0.05 through the plcent into the foetus nd therefore the stores of the neworn clves re low (Vn Sun et l., 1989; Njeru et l., 1994). Anlysis of Jgos et l. (1979) show, tht the concentrtions of β-crotene, s well s of vitmin A nd E in the lood plsm of foetuses in the ge of 8 to 9 months re much lower thn tht in the plsm of their cows. Figures 3 nd 4 show the results of dditionl exmintions of colostrum. Despite insignificnt differences in colostrum density it ppers tht the concentrtion of immunogloulins in colostrum of cows supplemented with higher doses of selenium nd vitmin E ws higher. Due to significnt (P < 0.05) difference etween groups E2 (34.08 ± 5.93 turidity units ccording to Snnk-Hoglnd (U ZST)) versus E1 nd C (21.38 ± 8.33 nd ± 5.41 U ZST, respectively), positive effect of selenium nd vitmin E on colostrum qulity cn e considered. Swecker et l. (1995) lso confirmed higher concentrtion of colostrl IgG in eef cows with higher selenium intke. On the other hnd, Rock et l. (2001) did not demonstrte ny positive effect of higher selenium intke on colostrl IgG in sheep. Lceter et l. (1996) likewise did not confirm differences in levels of colostrl immunogloulins in diry cows ut recorded positive effect of incresed selenium nd vitmin E intke on the quntity of colostrum nd milk produced. The ssessment of occurrence of clinicl forms of disese during the first 30 dys of the postprtum period reveled 5 treted cses of mstitis in 4 nimls nd 1 cse of endometritis in the cows of group C. There were 4 treted cses of mstitis in 3 cows of group E1. No cses of disese were detected in the nimls of group E2. Although the numers of nimls in seprte groups were smll, the results concerning the occurrence of disese during the postprtum period suggest possile positive influence of repeted dministrtion of selenium nd vitmin E on the reduction of clinicl cses of mstitis. This finding corresponds with the pulished dt on positive influence of selenium nd vitmin E dministrtion in cows during the lst stge of pregnncy on the reduction of cses of relted diseses (mstitis, nutritionl myopthy, retined plcent nd other reproductive disorders), s well s on improved function nd ctivity of the immune system (Smith et l., 1997; Allison nd Lven, 2000). On the sis of previously mentioned results it is possile to recommend repeted dministrtion of the product Selevit inj. in herds with sustntil selenium deficiency. The product should e dministered prior to prturition. Higher doses of selenium nd vitmin E cn e considered in cses when extreme vlues of selenium deficiency re detected. It hs to e noted, however, tht injectle products with higher selenium concentrtion re not ville on the mrket in the Czech Repulic. Veterinrins would therefore hve to exceed the mximum dose recommended y the mnufcturer of the product mentioned ove. Generl recommendtions for injectle products usully mention reltively low dosge of selenium nd 153

6 Originl Pper Vet. Med. Czech, 49, 2004 (5): in prticulr of vitmin E. The usul tretment ws one injection of pproximtely 700 IU of vitmin E nd out 50 mg of selenium dministered out 3 weeks efore clving. Positive effects of vitmin E on helth sttus nd improved function of the immune system were however descried on the sis of considerly higher doses ( IU of vitmin E) (Politis et l., 1995; Weiss, 1998; Allison nd Lven, 2000; Kol nd Seehwer, 2002). If higher dose of vitmin E is required in prctice, it is possile to dminister nother product contining vitmin E only. We re not of the opinion tht long-term low intke of selenium nd vitmin E y feed in diry cows cn e effectively compensted y injectle medicinl products. This is good wy just to stisfy incresed demnds of the orgnism during pregnncy or during periods of temporry lck of selenium nd vitmin E in the rtion. It cn e therefore concluded tht the dministrtion of the product contining selenium nd vitmin E to pregnnt diry cows showed positive effect on the increse of selenium nd vitmin E concentrtions in lood, increse of selenium nd immunogloulins concentrtions in colostrum, nd on the increse of T3 concentrtion in lood collected from the cows on the dy of prturition. In ddition, during the first month of the postprtum period trend of lower occurrence of clinicl forms of mstitis ws oserved. REFERENCES Allison R.D., Lven R.A. (2000): Effect of vitmin E supplementtion on the helth nd fertility of diry cows: review. Vet. Rec., 147, Arthur J.R., Nicol F., Becke G.J. (1990): Heptic iodothyronine deiodinse: The role of selenium. Biochem. J., 272, Awdeh F.T., Kincid R.L., Johnson K.A. (1998): Effect of level nd source of dietry selenium on concentrtions of thyroid hormones nd immunogloulins in eef cows nd clves. J. Anim. Sci., 76, Birringer M., Pilw S., Flohe L. (2002): Trends in selenium iochemistry. Nt. Prod. Rep., 19, Boud J., Jgos P., Dvork V. (1980): Fluorometric determintion of vitmins A nd E in lood plsm, colostrum nd the liver of c le (in Czech). Ceskoslov. Fysiol., 29, 351. Brzezinsk-Sleodzinsk E., Miller J.K., Quigley J.D., Moore J.R. (1994): Antioxidnt sttus of diry cows supplemented preprtum with vitmin E nd selenium. J. Diry Sci., 77, Crtens G. (1994): Cold thermoregultion in the neworn clf. Vet. Clin. North. Am. Food. Anim. Prct., 10, Dolezlov V. (1978): Methods of csein isoltion from humn milk nd exmintion of their efficiency y electrophoresis (in Czech). Biochem. Clin. Bohemoslov., 7, Fuchs O. (1996): Selenoproteins (in Czech). Chem. Listy, 90, Jgos P., Boud J., Geryk J. (1979): The plsm levels of vitmins A, E nd crotens in lte pregnncy nd their foetuses. Act Vet. Brno, 48, Jgos P. et l. (1981): Bsic iochemicl nd hemtologicl prmeters t domestic nimls nd new methods of lortory results expression (in Czech). SVS-Oddeleni veterinrni osvety, Prh. 29 pp. Kohrle J. (2000): The deiodinse fmily: selenoenzymes regulting thyroid hormone vilility nd ction. Cell. Mol. Life Sci., 57, Kol E., Seehwer J. (2002): The role of selenium compounds, vitmin E nd other fctors in the prevention of retined plcent: review (in Germn). Tierrztl. Umschu, 57, Lceter A., Bernucci U., Ronchi B., Nrdone A. (1996): Effects of selenium nd vitmin E dministrtion during lte stge of pregnncy on colostrum nd milk production in diry cows, nd on pssive immunity nd growth of their offspring. Am. J. Vet. Res., 57, Lrsen P.R., Berry M.J. (1995): Nutritionl nd hormonl regultion of thyroid hormone deiodinse. Ann. Rev. Nutr., 15, McDowell L.R., Willims S.N., Hidiroglou A., Njeru C.A., Hill G.M., Ocho L., Wilkinson N.S. (1996): Vitmin E supplementtion for ruminnt. Anim. Feed. Sci. Tech., 60, Njeru C.A., McDowell L.R., Wilkinson N.S., Lind S.B., Willims S.N. (1994): Pre nd postprtum supplementl DL-α-tocopheryl cette effects on plcentl nd mmmry vitmin E trnsfer in sheep. J. Anim. Sci., 72, Pvlt L., Illek J., Pechov A. (1999): Selenium nd vitmin E deficiency in clves (in Czech). In: Proceedings, Novemer 5, University of Veterinry nd Phrmceuticl Sciences, Brno Pvlt L., Pechov A., Illek J. (2000): Direct nd indirect ssessment of selenium sttus in c le comprison. Act Vet. Brno, 69, Pvlt L., Illek J., Pechov A. (2001): Blood nd tissue selenium concentrtions in clves treted with inorgnic or orgnic selenium compounds comprison. 154

7 Originl Pper Act Vet. Brno, 70, Pvlt L., Pechov A., Illek J. (2001): Musculr dystrophy in diry cows following chnge in housing technology. Act Vet. Brno, 70, Pvlt L., Illek J., Pechov A., Mtejicek M. (2002): Selenium sttus of c le in the Czech Repulic. Act Vet. Brno, 71, 3 8. Pvlt L., Podhorsky A., Vvrickov Z., Musilov L., Pechov A. (2002): Tretment of selenium deficienci in diry cows with injectle comintions of selenium nd vitmins (in Czech). Veterinrstvi, 52, Pvlt L., Prsek J., Podhorsky A., Pechov A., Hloun T. (2003): Selenium metolism in c le: mternl trnsfer of selenium to neworn clves t different selenium concentrtions in dms. Act Vet. Brno, 72, Politis I., Hidiroglou J.H., Btr T.R., Gilmore J.A., Gorewit R.C., Scherf H. (1995): Effects of vitmin E on immune function of diry cows. Am. J. Vet. Res., 56, Pechov A. (1992): Dignosis nd prevention of ft-cow syndrome in diry cows during periprtl period (in Czech). [PhD. Thesis.] University of Veterinry nd Phrmceuticl Sciences, Brno. 170 pp. Rock M.J., Kincid R.L., Crtens G.E. (2001): Effects of prentl source nd level of dietry selenium on pssive immunity nd thermometolism of neworn lms. Smll Ruminnt Res., 40, Slnin L., Vjd V., Blzej J. (1976): Turidimetric nlysis of immunogloulins in clves nd their clinicl evlution (in Slovk). Veterinrstvi, 9, Smith B.P. (1996): Lrge niml internl medicine: diseses of horses, c le, sheep, nd gots. 2nd ed. Mosy, Yer Book, Inc pp. Smith K.L., Hogn J.S., Weiss W.P. (1997): Dietry vitmin E nd selenium ffect mstitis nd milk qulity. J. Anim. Sci., 75, Swecker W.S., Thtcher C.D., Eversole D.E., Blodge D.J., Schurig G.G. (1995): Effect of selenium supplementtion on colostrl IgG concentrtion in cows grzing selenium-dependent pstures nd on postsuckle serum IgG concentrtion in their clves. Am. J. Vet. Res., 56, Underwood E.J., Su le N.F. (1999): Selenium. In: Minerl Nutrition of Livestock. CAB Interntionl, Vn Sun R.J. (1990): Rtionl pproch to selenium supplementtion essentil. Feedstuffs, (Jn 15), Vn Sun R.J., Herdt T.H., Stowe H.D. (1989): Mternl nd fetl vitmin E concentrtions nd selenium-vitmin E interreltionships in diry c le. J. Nutr., 119, Vrzgul L., Sokol J. (1990): Enzyme profile interprettion (in Slovk). In: Vrzgul et l.: Metolic disorders in frm nimls nd their prohylxis (in Slovk). Prirod, Brtislv Weiss W.P. (1998): Requirements of ft-solule vitmins for diry cows: review. J. Diry Sci., 81, Wichtel J.J., Crigie A.L., Freemn D.A., Vrel-Alvrez H., Willimson N.B. (1994): Effect of selenium nd iodine supplementtion on growth rte nd on thyroid nd somtotropic function in diry clves t psture. J. Diry Sci., 79, Zimmermnn M.B., Kohrle J. (2002): The impct of iron nd selenium deficiencies on iodine nd thyroid metolism: iochemistry nd relevnce to pulic helth. Thyroid, 12, Received: Accepted er corrections: Corresponding Author MVDr. Leos Pvlt, PhD., Clinic of Diseses of Ruminnts, Fculty of Veterinry Medicine, University of Veterinry nd Phrmceuticl Sciences, Plckeho 1 3, Brno, Czech Repulic Tel , fx , e-mil: pvltl@vfu.cz 155