Effect of Dietary Selenium on Small Intestine Villus Integrity in Reovirus-Challenged Broilers

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1 Interntionl Journl of Poultry Science 8 (9): , 2009 ISSN sin Network for Scientific Informtion, 2009 Effect of Dietry Selenium on Smll Intestine Villus Integrity in Reovirus-Chllenged Broilers Jessic Red-Snyder, F.W. Edens*,.H. Cntor,.J. Pesctore nd J.L. Pierce 1 Deprtment of Poultry Science, North Crolin Stte University, Rleigh, NC, US 2 Deprtment of niml nd Food Sciences, University of Kentucky nd lltech-university of Kentucky Nutrition Reserch llince, Lexington, KY 40546, US strct: Enteric vin Reoviruses (RV), ssocited with mlsorption, lower weight gins nd incresed mortlity in roiler chickens, trget enterocytes on intestinl villi cusing villus dysfunction nd decresed digestion nd sorption of nutrients. This investigtion exmined whether enteric RV infection with or without dietry Selenium (Se) (orgnic or inorgnic) ffected smll intestinl integrity. Eggs from Co 500 roiler reeders fed low-se semi-purified diets with no supplementl Se, or with 0.3 ppm supplementl Se provided y orgnic Se (Se-yest, Sel-Plex, lltech, Inc., Nicholsville, KY, US), or y sodium selenite, were htched nd the chicks were sujected to the sme three dietry Se tretments s their respective prents. t htch, 30 chicks per dietry Se tretment were plced into either control or RV-infected groups in heted 4.2 tteries in seprte isoltion rooms. RV-infected chickens were given orlly RV-CU98 (10 pfu/chick in 0.5 ml) nd control chickens received medium only. Intestinl trcts from 21-d-old chickens were exmined histomorphometriclly reveling longer nd more nrrow villi, greter surfce perimeter, more shllow crypt depth nd significntly greter height to crypt depth (H:D) rtios in Sel-Plex-fed control nd infected irds, compred with respective vlues from irds fed no supplementl Se or sodium selenite. The differences in H:D rtios etween Se tretments indictes tht Sel-Plex is more effective thn either no Se or sodium selenite supplementtion in protecting the integrity of the smll intestine villi. Key words: Sel-Plex, histomorphometry, intestine, reovirus, roiler, selenium, selenium yest INTRODUCTION pucity of pulished investigtions link Selenium (Se) with the responses of poultry species to virl infections. For chickens, one study (Pnd nd Ro, 1994) in which vitmin E nd Se were supplemented to diets lredy dequte in these nutrients reported tht, compred with unsupplemented groups, vitmin E nd Se supplements enhnced immune function, including higher geometric men titers of the tue gglutintion test ginst Infectious Bursl Disese Virus (IBDV) nd higher numers of rosette-forming cells in the peripherl lood. Newcstle Disese (ND) virl infections lso pper to e ffected y vitmin E nd Se supplementtion. Bssiouni et l. (1990) oserved improved resistnce ginst ND, incresed ntiody titers nd improved weight gin ssocited with Se nd vitmin E supplementtion. Swin et l. (2000) hve shown tht roiler chicken responses to ND vccine were enhnced y Se nd vitmin E supplements greter thn NRC (1994) requirements. dditionlly, Mrin et l. (2003) reported incresed ntiody titers ginst IBDV nd ND, incresed serum protein levels, nd prevention of ursl dmge in fltoxin-b-1- exposed chickens when the chickens were fed dietry supplements of Se nd vitmin E. Singh et l. (2006) reported synergistic effect etween vitmin E nd Se in chickens given ND vccine. ND-vccinted chickens hd higher hemgglutintion inhiition titers when fed the comintion of Se nd vitmin E long with higher circulting levels of immunogloulins nd circultory immune complexes. There re numerous economiclly importnt RN viruses tht ffect domestic poultry. mong these re the vin Reoviruses (RV), which re species-specific nd hve rod rnge of virulence in chickens (Roertson et l., 1984). RV cn cuse infection in joints nd tendons, respirtory trct nd in the intestinl trct. Recently, there hve een numerous field cses of enteric RV infections leding to mlsorption syndrome, moderte to severe depression of weight gin nd incresed mortlity. Mlsorption syndrome ws investigted y Jensen et l. (1991) who found tht oth Se nd vitmin E were effective in reducing mortlity. In fct, Swick (1995) hs recommended tht Se nd vitmin E e supplemented to the highest llowle dietry level to reduce RV-relted mortlity ssocited with mlsorption syndrome. The higher metolic rtes of the modern high metyielding roiler chicken might contriute to the severity of RN virl infection, ecuse the RN viruses depend on high levels of oxidtive stress to fcilitte repliction. Thus, it is importnt to investigte the role Se might ply in RN virl infection. This work ws conducted to exmine the influence of Se provided y oth the 829

2 MTERILS ND METHODS Chicks: Co500 roiler chickens were htched from eggs produced y reeder hens tht hd een mintined on low-se semi-purified diet (<0.02 ppm) with no supplementl Se, or with 0.3 ppm supplementl Se provided y orgnic Se (Se-yest, Sel-Plex, lltech, Inc., Nicholsville, KY, US), or y sodium selenite. Htchling chickens were plced in pens in heted rooder tteries nd were sujected to the sme three dietry Se tretments s their respective prents (Tle Int. J. Poult. Sci., 8 (9): , 2009 mternl crryover nd the chick diet on intestinl Sttistics: ll dt from this completely rndomized morphology of roiler chickens chllenged with n experimentl design were nlyzed using the generl enteric RV. liner models procedure of SS (SS Institute, 1996). For the histomorphometric clcultions, ten mesurements for ech prmeter from ech ird per tretment, yielding 50 mesurements per prmeter men, were nlyzed s one-wy nlysis of vrince. Fisher s lest significnt difference ws used to test differences etween mens only when the nlysis of vrince indicted significnce t p<0.05 (Motulsky, 2005). RESULTS Body weight ws significntly depressed y reovirus 1). Vitmin E ws dded to ll the diets t 15 IU/kg to infection t oth 14 d (control = 514 g; infected = 362 g) prevent the development of pncretic firosis nd nd 21d (control = 962 g; infected = 724 g) post exudtive dithesis in the group given no supplementl chllenge, ut there were no differences mong ody Se. The chick diets used the sme ingredients weights for the Se tretments within either control or contined in the reeder diets. However, the proportions infected groups. It ws of interest, however, tht weight of the ingredients were djusted to meet the nutrient gin from d for Sel-Plex-fed chicks ws somewht requirements of young roiler chickens. Body weights greter thn tht of either the no Se- or sodium selenitewere determined t 14 nd 21 d of ge nd t those fed chicks in oth control (no Se = 466 g, Sel-Plex = 476 ges tissues were collected for other nlyses relted g; selenite = 460 g) nd infected (no Se = 355 g, Sel-Plex to Se nd RV infection. = 388 g, selenite = 342 g) groups. Reovirus infection did not significntly ffect smll Reovirus (RV) chllenge: On the dy of htch, 30 intestinl segment reltive weights except tht of the chickens from ech of the three dietry tretments were jejunum, which ws incresed y the infection (Tle 2). plced into either control or RV-infected groups (totl of dietry Se effect ws seen in the reltive weights of the 180 chickens) in heted metl-growing tteries in duodenum with Sel-Plex decresing the reltive weight seprte isoltion rooms. Ech of the chickens in the in oth control nd virus-chllenged irds nd the RV-infected groups ws given n orl gvge of 0.5 ml selenite-fed diet cusing n increse in reltive weights 4.2 of the reovirus RV-CU98 (10 pfu/chick; Heggen-Pey in oth control nd infected irds compred with Selet l., 2002); control chickens were given the medium Plex. This dietry effect cused significnt diet x virus only. t 21 d of ge, the chickens were killed y cron interction for duodenum reltive weight. The lrge dioxide sphyxition, intestinl trcts were dissected to intestine reltive weights were decresed significntly y mesure totl nd segmentl weight nd length nd reovirus chllenge, ut Sel-Plex incresed reltive tissues were collected for histomorphometry. weight in oth control nd infected groups compred with no supplementl Se (Tle 2). Reovirus infection Histomorphometry: n individul ird ws regrded s did not ffect length of the intestines (dt not shown). the experimentl unit, nd there were five irds per Se However, there were sttisticlly significnt diet effects nd virus group nlyzed. totl of 30 rndomly- on verge Gstrointestinl Trct (GIT) length. Feeding selected chickens were used in this phse of the overll the diet with no Se supplement incresed GIT length y study. fter dissection, the duodenum nd ilel (divided lmost 9% (dt not shown) compred with the two Se into jejunum nd ileum) segments were collected nd diets (p<0.05). fixed in Crnoy s solution. Tissues were processed for Intestinl histomorphometric nlysis of the duodenum histology nd stined with hemtoxylin-eosin. (Tle 3) reveled oth diet nd reovirus infection effects computerized microscope-sed imge nlyzer on the different prmeters. The perimeter of the villus (Southern Micro Instruments, tlnt, G) ws used to ws significntly incresed in the Sel-Plex-fed control determine the histomorphometric prmeters for villus nd infected groups, compred with respective vlues height, villus width t its mid-height, villus perimeter for the no Se nd selenite groups. There ws no length, crypt depth, externl muscle lyer thickness nd difference etween control nd selenite for villus villus height to crypt depth (H:D) rtio (Fn et l., 1997). perimeter. Villus height ws significntly greter for irds The criteri for selection of histologicl sections for fed Sel-Plex compred with the no Se-fed nd selenitefed exmintion were sed on the presence of n intct irds in oth control nd reovirus-infected groups. lmin propri nd villi tht were perpendiculrly Villus width ws greter in selenite-fed irds in the sectioned through the midline xis. control group compred with no Se-fed nd Sel-Plex-fed 830

3 Tle 1: Composition of torul-yest diets, which were provided s mens to supply either no supplementl Se (<0.02 ppm), orgnic Se s Sel-Plex (0.3 ppm), or sodium selenite (0.3 ppm) to chickens htched from eggs from prents who hd consumed the sme diets Ingredients of Diet Ingredients No Se Sel-Plex Selenite Corn (%) Strch (%) Torul yest, (%) Soyen mel, dehulled (%) Whet midds (%) Diclcium phosphte ( ) (%) Limestone, feed grde ( 38%) (%) Iodized slt (%) Trce minerl mix Vitmin mix (+15 IU vitmin E/kg) (%) DL-Methionine (99%) (%) Sodium selenite mix* (%) Sel-Plex mix* (%) ME, kcl/kg Totl P (%) ville P (%) Methionine (%) Cysteine (%) C (%) Lysine (%) Tryptophn (%) DM (%) CP (%) Crude ft (%) Crude fier (%) Moisture (%) TS (%) Tle 2: Influence of reovirus infection nd selenium source effects on Gstrointestinl Trct (GIT), duodenum, jejunum, ileum nd lrge intestine reltive weights in 21-d-old chickens Reltive Weights (%) [Section Wet Weight/GIT Wet Weight] x Dietry Tretments Se Duodenum Jejunum Ileum Lrge Intestine Control Bsl < Control Sel-Plex 0.3 c Control N Selenite c Pooled Mens ± SEM 20.66± ± ± ±1.05 Infected Bsl < c Infected Sel-Plex Infected N Selenite c Pooled Mens ± SEM 21.77±0.79 B 31.42± ±0.89 B 20.73±1.05 c In column, mens with unlike superscripts differ significntly (p<0.05) B In column, mens with unlike superscripts differ significntly (p<0.05) irds. However, in the infected groups, no Se-fed irds thickness ws incresed in virus-chllenged chickens hd the gretest villus width followed y selenite- nd nd ws gretest in Sel-Plex-fed nd no Se-fed irds. In Sel-Plex-fed groups, respectively. There ws the control groups, sodium selenite-fed irds hd the significnt virus-relted increse in crypt depth nd there gretest muscle thickness followed y no Se-fed nd ws significnt increse in crypt depth in the no Se-fed Sel-Plex-fed, respectively. nd selenite-fed irds compred with Sel-Plex-fed irds. The results for histomorphometric nlysis for the Within oth the control nd infected groups, the villus jejunum re shown in Tle 4. The perimeter of the height to crypt depth (H:D) rtio for chicks fed either no villus ws incresed significntly in the Sel-Plex control Se- or selenite-supplemented diets ws incresed nd infected groups compred with the perimeters of the compred with those fed Sel-Plex. Musculris extern no Se nd selenite groups. There were no significnt 831

4 Tle 3: Selenium (Torul yest with No Se, Sel-Plex (Sel-Plex), or sodium selenite) nd reovirus influence on morphology (men±sem of villus perimeter, height, width, crypt depth, villus height to crypt depth [H:D] rtio nd muscle [musculris extern] thickness) of duodenum in 21 dold chickens Control Control Control Infected Infected Infected Prmeter No Se Sel-Plex Selenite No Se Sel-Plex Selenite Villus, µm Perimeter 2203± ± ± ± ± ±149 Height 1058± ± ± ± ±48 983±70 c c c Width 112± ± ± ± ± ±9.9 c Crypt depth, µm 195± ± ± ± ± ±22.0 c c c H:D rtio 5.43± ± ± ± ± ±0.28 c Muscle, µm 292± ± ± ± ± ±10.8 cd In row, mens±sem with unlike superscripts differ significntly, p<0.05, n = 50 for ech men presented differences etween no Se-fed nd selenite-fed groups for villus perimeter. The infection-relted depression in villus height ws not significnt in the Se-fed groups, ut there ws significnt depression in the no Se-fed group due to infection. Sel-Plex-fed chickens hd significntly incresed villus heights compred with the other dietry tretments. These responses did not induce diet x virus interction (p>0.05). Jejunum villus width ws not ffected y infection, ut the feeding of Sel-Plex cused the development of nrrower villus width compred with those of the no Se nd selenite-fed chickens. This dietry effect resulted in significnt diet x virus interction for villus width. The crypt depth ws less (p<0.05) in Sel-Plex-fed irds in oth the control nd virus-infected groups compred with no Se nd sodium selenite tretments where n incresed crypt depth ws oserved in oth control nd infected groups. There were significnt Se nd virl effects for height to crypt depth rtios. Sel-Plex-fed irds hd the lrgest rtios in oth control nd infected groups nd no Send sodium selenite-fed irds hd significntly smller H:D rtios. Diet nd virl effects were evident for musculris extern muscle thickness in the ileum, which showed tht oth Se tretments resulted in incresed muscle thickness fter infection. Birds fed no supplementl Se hd no chnge in muscle thickness fter infection. The results for histomorphometric nlysis for the ileum re shown in Tle 5. In the control groups, the torul yest-fed no Se tretment resulted in the longest perimeter followed y Sel-Plex nd selenite tretments, respectively, ut in the infected group, the no Se-fed tretment resulted in the shortest perimeter followed y the Se tretments tht did not differ etween themselves. These responses resulted in significnt diet X virus interction. There ws significnt depressive effect of virl infection on villus height in ll dietry tretments. Villus height ws negtively ffected y virl infection in ll Se tretments. In the control groups, the no Se- nd Sel-Plex-fed irds hd longer villi thn selenite-fed irds nd in the infected groups, Sel- Plex-fed irds hd longer villi thn either no Se- or selenite-fed irds. Villus width ws incresed in the infected irds fed either no Se or sodium selenite tretments, ut villus width in the Sel-Plex-fed irds did not differ from controls. This difference resulted in significnt diet x virus interction for villus width. The crypt depth ws less in Sel-Plex-fed irds in oth the control nd virus-infected groups. No Se nd sodium selenite tretments resulted in incresed crypt depth in oth the control nd the infected groups. There were significnt Se nd virl effects for height to crypt depth (H:D) rtios. Sel-Plex-fed irds hd the lrgest H:D rtios in oth control nd infected groups nd no Se nd sodium selenite fed irds hd significntly smller H:D rtios. Diet nd virl effects were evident for musculris extern muscle thickness in the ileum, which showed tht oth Se tretments resulted in incresed muscle thickness fter infection. Birds fed no Se hd no chnge in muscle thickness fter infection. DISCUSSION There is no dout tht RV infection cuses decresed weight gin in chickens. Prt of the cuse for this decresed weight gin fter infection is ttriuted to the fct tht the virus hijcks the protein synthesis mechnism in the cells erly in the infection (Guy, 1998). Reel et l. (2004) report tht y 14 d post chllenge, chickens exposed to n enteric RV egin to recover from the initil infection s evidenced y less severity of lesions in the villus nd crypt regions of the intestine. n externl indiction of the RV infection cn e oserved s poor fethering, ut s the infection egins to resolve, the protein synthesis mechnism regins its efficiency. In this study, weight gin ws suppressed y reovirus infection through 21 d of ge. However, of note, Sel-Plexfed chickens were gining weight t slightly fster rte t 21 d thn were chickens supplemented with no Se or selenite in oth control nd infected groups. This performnce difference suggests tht n improved ntioxidnt sttus in Sel-Plex-fed chickens fcilittes fster recovery fter RV infection. Mhmoud nd Edens (2003) hve demonstrted tht orgnic Se s Sel-Plex hs the ility to induce higher Se-dependent ntioxidnt enzyme ctivities thn do sodium selenite or no Se supplements. The improved redox sttus then cn e directly relted to improved performnce of roiler chickens fed Sel-Plex (Edens nd Gowdy, 2004). Suri (2006) reviewed extensively the helth effects of dietry Se supplementtion. He pointed out tht Se does 832

5 not prevent virus-induced disese, ut Se Whether this ws response leding to fster recovery supplementtion ppers to ply pivotl role in from the RV infection or for some other reson ws not reducing the severity of the infection nd tht oservtion determined in this study. Nevertheless, it ws shown in is consistent with the results of this study with erlier work tht selection for rpid growth cused n enteric RV infection in roiler chickens. The improved increse in mss of the smll intestine (Mitchell nd helth sttus imprted y the feeding of Se is ttriuted Smith 1991; O Sullivn et l., 1992; Smith et l., 1990). to enhnced immune responses nd incresed ctivity Thus, in this study, our evidence suggested tht Sel-Plex of ntioxidnt enzymes such s glutthione peroxidse supplementtion fcilitted the expression of genetic (Suri, 2006; Mhmoud nd Edens, 2003) nd potentil in roiler chickens even when they were thioredoxin reductse (Edens nd Gowdy, 2004). Even chllenged y n enteric RV infection. though there re improved redox sttus nd enhnced One of the most impressive nd consistent oservtions immunity ssocited with the feeding of Sel-Plex, there mde in this histomorphometry study ws tht Sel-Plex re other physiologicl mnifesttions of the influence generlly mintined longer nd more slender villi thn of Se on the overll heth sttus of the chicken. either sodium selenite or no supplementl Se feeding. Erlier studies hve suggested tht Se hs role in Histomorphometric nlysis indicted tht incresed regulting virus repliction. Blnsky nd rgirov villus height nd perimeter, s well s muscle thickness (1981) concluded tht Se depressed RN-dependent nd crypt depth in the duodenum, jejunum nd ileum RN polymerse in n oncornvirus s n indictor of were ssocited with Sel-Plex feeding compred with reverse trnscriptse ctivity. Blnsky nd rgirov either sodium selenite or no Se (Tle 3, 4 nd 5). (1981) further hypothesized tht Se prevents integrtion Muscle thickness generlly ws greter in the ileum of the virus genome with the host s DN. Similr thn in the duodenum in oth control nd infected oservtions were mde erlier y oth Billrd nd Peet chickens, ut muscle thickness ws gretest in the (1974) nd Oxford (1973) who reported tht jejunum segment compred with oth duodenum nd selenocystine nd selenocystmine inhiited RN- ileum. dependent RN polymerse ctivity in influenz 1, 2 shortened villus height nd lower villus height to nd B viruses. Schruzer nd Scher (1994) lso crypt depth rtio is directly correlted with incresed reported tht Se cuses symptomtic improvements enterocyte turnover (Fn et l., 1997). This condition ws nd slows the course of the HIV disese possily found in RV-infected chickens nd ws most prominent through the inhiition of reverse trnscriptse ctivity in in the irds fed sodium selenite or no supplementl Se the HIV-virus-infected ptients. Schruzer nd Scher in oth control nd RV-infected groups. In the present (1994) concluded tht it is possile tht Se might lso study, nlysis of those prmeters strongly indicted prevent the repliction of HIV nd retrd the development tht Sel-Plex feeding mintined the integrity of the of IDS in newly HIV-infected sujects. The depressive intestinl trct s indicted y tller villi nd n influence of Se on reverse trnscriptse ctivity in RN incresed height to crypt depth rtio. Lower villus height viruses is very importnt nd suggests tht Se is to crypt depth rtios in oth control nd infected groups needed y the host to resist expression nd possily suggests tht the increses in villus height nd trnsmission of viruses. perimeter ssocited with Sel-Plex tretment re not In this study (dt not shown in tles), Se incresed the ssocited with enterocyte turnover rtes ut insted reltive weight of the hert [Sel-Plex (0.512 g/100 g BW); with mintennce of the enterocyte popultion covering sodium selenite (0.515 g/100 g BW); no Se (0.473 g/100 the villus. This mintennce effect my possily e g BW),]. This positive effect on hert helth is importnt ttriuted to improved redox sttus in the gstrointestinl ecuse congestive hert disese is known to induce trct, which would result in less oxidtive stress during scites, which cn led to mortlity in modern, high- norml nd infective periods. n extension of this yielding roilers (Roch et l., 2000). Reltive weights of oservtion is tht with n improved redox sttus, it is the whole gstrointestinl trct were elevted in control proly more difficult for the reovirus to replicte within nd infected irds y feeding Sel-Plex (4.09 g/100 g BW; the enterocytes of Sel-Plex-fed chickens g/100 g BW, respectively) compred with sodium Reel et l. (2004) hve descried pthologicl chnges selenite (3.58 g/100 g BW; 4.11 g/100 g BW, ssocited with mlsorption syndrome in chickens s respectively) or no supplementl Se (3.80 g/100 g BW; eing chrcterized y degenerte epithelil cells in the 3.87 g/100 g BW, respectively). When the crypt, villus trophy nd low villus height to crypt depth histomorphometry of the intestinl segments ws rtio similr to the condition ssocited with intestinl exmined, it ws pprent tht the muscle thickness of segments from no Se- nd sodium selenite-fed the ileum nd duodenum, very lrge segments of the chickens in this study. Thus, the improved weight gin gstrointestinl trct, were not ffected consistently y fter the pek infective stte in the chicken fed Sel-Plex either of the dietry Se tretments. Selenium generlly might e relted to 1) greter surfce re to volume incresed muscle thickness in the infected chickens. rtio in the villi, 2) incresed ility to ssimilte 833

6 Tle 4: Selenium (Torul yest with No Se, Sel-Plex (Sel-Plex), or sodium selenite) nd reovirus influence on morphology (men± SEM of villus perimeter, height, width, crypt depth, villus height to crypt depth [H:D] rtio nd muscle [musculris extern] thickness) of jejunum in 21-d-old chickens Control Control Control Infected Infected Infected Prmeter No Se Sel-Plex Selenite No Se Sel-Plex Selenite c c c Villus, µm Perimeter 1889± ± ± ± ± ±45 c c Height 866± ±67 740±29 782± ±63 731±34 Width 135± ± ± ± ± ±11.3 Crypt depth, µm 257± ± ± ± ± ±12.6 c c cd d H:D rtio 3.42± ± ± ± ± ±0.27 Muscle, µm 390± ± ± ± ± ±16.2 c In row, mens±sem with unlike superscripts differ significntly, p<0.05, n = 50 for ech men presented Tle 5: Selenium (Torul yest with No Se, Sel-Plex (Sel-Plex), or sodium selenite) nd reovirus influence on morphology (men± SEM of villus perimeter, height, width, crypt depth, villus height to crypt depth [H:D] rtio nd muscle [musculris extern] thickness) of ileum in 21-d-old chickens Control Control Control Infected Infected Infected Prmeter No Se Sel-Plex Selenite No Se Sel-Plex Selenite c c Villus, µm Perimeter 1872± ± ± ± ± ±37 c c Height 877±21 798±23 679±24 599±40 744±25 602±53 Width 118± ± ± ± ± ±19.1 c Crypt depth, µm 235± ± ± ± ± ±14.2 c c d d H:D rtio 3.73± ± ± ± ± ±0.26 Muscle, µm 391± ± ± ± ± ±18.2 cd In row, mens±sem with unlike superscripts differ significntly, p<0.05, n = 50 for ech men presented nutrients compred with selenite- nd no Se-fed irds, 3) decresed enterocyte cell deth ssocited with oxidtive stress, nd 4) enhnced immunity during the infection. Conclusion: In conclusion, it cn e stted tht dietry Se supplementtion hs improved performnce of roiler chickens ever since it ws introduced s n pproved feed ingredient in Nevertheless, the dvent of the modern roiler, which is fster growing nd significntly lrger ird tht the roiler of 1974, hs plced it t risk for distress from incresed oxidtive stress due to its higher rte of muscle growth nd metolism. It hs een demonstrted tht it is possile to improve the performnce of the modern roiler if simple replcement of sodium selenite with Sel-Plex, which llows for development of n improved redox sttus (Edens, 2001). This study demonstrted tht Sel- Plex lso hs mjor influence on intestinl morphology, which fcilittes the potentil for improved nutrient ssimiltion. This potentil is especilly importnt for chickens tht hve een exposed to enteric viruses, such s the enteric reovirus, which hs limited time of residence ut long-lsting effects on ird performnce. s the ird egins to recover from the RV infection out 14 d fter virl chllenge (Reel et l., 2004), it is importnt to resume rpid nd efficient ssimiltion of nutrients in the GIT. These results suggest tht Sel-Plex, more so thn sodium selenite, hs the potentil to improve nutrient ssimiltion in reovirus-infected chickens. These oservtions suggest tht the improved performnce of roiler chickens fed Sel-Plex cn e prtilly explined y improved integrity of the intestinl trct nd possily y improved immune sttus. REFERENCES Blnsky, R.M. nd R.M. rgirov, Sodium selenite inhiition of the reproduction of some oncogenic RN-viruses. Experienti, 37: Bssiouni,.., M.M. Zki nd M.M. Hdy, Effect of vitmin E nd selenium on the immune response of chickens ginst living Newcstle disese vccine. Vet. Med. J. Giz, 38: Billrd, W. nd E. Peet, Sulfhydryl rectivity: mechnism of ction of severl ntivirl compounds-selenocystine, 4-(2-propinyloxy)-etnitrostyrene nd cetylrnotin. ntimicro. gents Chemother, 5: Edens, F.W., Involvement of Sel-Plex in physiologicl stility nd performnce of roiler chickens. In: Lyons, T.P. nd K.. Jcques (Eds.), Science nd Technology in the Feed Industry. Time for nswers. Nottinghm University Press, Nottinghm, UK. 17: Edens, F.W. nd K.M. Gowdy, Selenium sources nd selenoproteins in prcticl poultry production. In: Lyons, T.P. nd K.. Jcques (Eds.), Nutritionl Biotechnology in the Feed nd Food Industries, Nottinghm University Press, Nottinghm, UK. 20: Fn, Y., J. Croom, V. Christensen, B. Blck,. Bird, L. Dniel, B. McBride nd E. Eisen, Jejunl glucose uptke nd oxygen consumption in turkey poults selected for rpid growth. Poult. Sci., 76: Guy, J., Virus infections of the gstrointestinl trct of poultry. Poult. Sci., 77:

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