Study on Poultry Coccidiosis in Tiyo District, Arsi Zone, Ethiopia

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1 Interntionl Journl of Poultry Siene 7 (3): 51-56, 008 ISSN Asin Network for Sientifi Informtion, 008 Study on Poultry Coidiosis in Tiyo Distrit, Arsi Zone, Ethiopi 1 3 Gethew Gri, Gethew Tilhun nd Ph. Dorhies Ntionl Animl Helth Reserh Center, P.O. Box: 4, Sebet, Ethiopi Aklilu Lemm Institute of Pthobiology, Addis Abb University 3 Eole Ntionl Veterinry, Toulouse, Frne 1 Abstrt: The objetive of this study ws first to investigte the prevlene of poultry oidiosis nd to identify the oidil speies ourring in the study re on lol strin nd Rhode Islnd Red breed hiken. The study involved questionnire survey, fel exmintion, neropsy exmintion nd identifition of oidil speies bsed on their morphology, prediletion site in the intestine nd sporultion time. More thn 75% respondents indited tht poultry prodution nd inome generted from poultry prodution in the rurl ommunity is the mjor inome soure for femles nd youth nd bloody dirrhe predominntly ppered during wet seson thn hlky, yellow or green dirrhe. Publi nd privte veterinry servie enters hve no nti oidil drugs nd other mediments used for poultry diseses. Frequeny detetion of ooyst in the fel smples from Rhode Islnd Red breed nd lol strin hiken ws 80.65% nd 61.5% respetively. This finding indited tht oidil infetion in Rhode Islnd Red breed ws signifintly higher thn in lol strin hiken (p < 0.05). The lesion sore nd men ooyst output per grm fees ws lso onsiderbly higher in Rhode Islnd Red breed thn in lol strin hiken (p < 0.05, p < respetively), whih my be the differene due to mngement system nd breed. Clinil oidiosis ourrene in Rhode Islnd Red breed nd lol strin hiken ws.58% nd 1.5% respetively. There ws no sttistilly signifint differene in linil oidiosis ourrene between the two genotype hikens nd system. Eimeri speies identified in desending order of their ourrene were E. tenell, E. ervulin, E. netrix, E. mxim nd E. mitis. Mixed infetions were the predominnt in both prodution systems. E. mitis ws dignosed for the first time in Ethiopi. Key words: Coidi, eimeri, infetion, Lol strin hiken, prevlene nd Rhode Islnd Red breed, Introdution Coidiosis remins one of the mjor disese problems of poultry in spite of dvnes mde in prevention nd ontrol through hemotherpy, mngement nd nutrition (Grt et l., 1996). E. tenell nd E. netrix re the most pthogeni speies. E. ervulin, E. mxim nd E. mivti re ommon nd slightly to modertely pthogeni; E. brunetti is unommon but pthogeni when it does our. E. mitis, E. preox nd E. hgni re reltively non-pthogeni speies (Soulsby, 198; Lillehoj nd Trout, 1993). The speies of oidi identified in Ethiopi re E. tenell, E. netrix, E. mxim nd E. ervulin (Methusel et l., 00; Ashenfi et l., 004). Quntittive losses due to oidiosis in Ethiopi re not well doumented, but Thus, the objetive of this study is to ondut prevlene study of poultry oidiosis in Tiyo Wered, Arsi Administrtive Zone of the Oromi Regionl Stte, Ethiopi. The study re my represent the mid nd highlnd gro-eology of the zone. Besides the indigenous strin hiken under free- rnge mngement system, the study inluded the Rhode Islnd Red breed kept under lrge-sle deep litter mngement system to observe the importne of oidiosis in this breed under intensive frm. The speies of Eimeri ourring in the re were identified nd rnked bsed on their frequeny of ourrene. Mterils nd Methods Study Are: Tiyo Wered is loted 175 km Southest to o o Kinung hi et l. (004) hs reported tht oidiosis Addis Abb t N nd E, 436 ontributes to 8.4% loss in profit in lrge-sle frms msl nd it is one of the Twenty Wereds found in Arsi nd 11.86% loss in profit in smll-sle frms. Losses Zone of Oromi Regionl Stte situted in the North due to mortlity following severe outbrek my be Western prt of the Zone. Poultry popultion in Tiyo devstting nd inidene rtes s high s 80% were Wered is estimted to be out of whih 500 re observed to our in the form of n outbrek in Ethiopi exoti breeds of Rhode Islnd Red nd Bovns breed. (Almrgot, 1987). However, morbidity losses my be The indigenous lol strin hikens found in the study even more ostly without the produers being wre tht re re not well studied nd hrterized for their their floks hving ny disese problem. geneti identity. However, the geneti potentil of these 51

2 Gri et l.: Poultry Coidiosis hikens in egg nd met prodution is onsidered s Questionnire survey: The survey ws onduted on low (Nsser, 1998). At the smllholder frmers level 100 frmers hving diret prtie in poultry prodution lol strin hiken re rered in trditionl bkyrd from 10 Pesnt Assoitions (PA), 10 frmers in eh system. The birds feed by svenging round the PA. Pre-tested questionnire ws developed nd used residene re nd osionlly supplemented with to gther informtion regrding generl prodution food residues nd erels. The housing nd nesting system in the study re, ssessment of hiken ple provision re poorly nd onstruted from the disese ourrene nd frmer s tretment prties. lolly vilble mterils. The min soure of Rhode Disese ssessment in PA s ws bsed on informtion Islnd Red breed is Adm Poultry Breeding nd regrding linil mnifesttions of some ommon Multiplition Center. The birds re sold to the frmers diseses enountered nd their sesonl ourrene. through the Wered Agriulturl extension progrm with government subsidy. Cross setionl study: The study ws onduted from September to Deember 003 GC. The study Study popultion: Lol strin hikens were bought methodology involved quntittive nd qulittive diretly from the frmers rndomly in five mrket enters. nlysis of fel exmintion to investigte ooyst Physil pperne, size of the hiken nd short dishrge, neropsy exmintion to grde the intensity interview of owners bout the pedigree of their hiken of lesions indued (lesion soring), lotion of lesion in ws mde to exlude exoti blood or rossbreed the intestine nd identifition of the Eimerin speies hiken. Most hiken bought for the study ws were performed. Mesurement the size nd shpe of pproximtely in the rnge of growers nd dult ge sporulted ooyst ws done to identify the speies of groups. Systemti rndom smpling method ws Eimeri enountered in the study re. pplied during seletion nd purhse hiken. The study ws plnned to investigte Rhode Islnd Red Fel exmintion nd eimeri speies identifition: breed hiken tht were kept under smllholder poultry The lol strin hiken purhsed ws kept overnight prodution system. However, in prtil relity these in the lbortory for t lest 18 hours. The im ws to hikens were rossbreed with the lol hikens sine ollet fel smple from eh individul bird nd to they were mnged together under extensive system. reord nte mortem linil ondition of eh bird. The Thus, it ws diffiult to get the pure breed exept F nd fel smple of eh bird ws blended by mortr nd F 3 genertion. Therefore, the smples from Rhode pistol nd ooyst per grm fees ws lulted bsed Islnd Red breed were olleted from Adm Poultry on the tehnique desribed by MAFF (1979). Positive Breeding nd Multiplition Center to observe the smples were further exmined for speies importne of oidiosis in this breed nd to ompre identifition bsed on ooyst size, sporultion time, the prevlene between breeds nd mngement shpe nd olor of the ooysts. systems. The frm holds bout hikens under The proedure pplied to hrvest ooysts ws by intensive deep litter mngement nd totl of 31 live flottion tehnique using sturted Sodium Chloride birds with different ge groups nd equl sex proportion slt solution (Conwy nd MKenzie, 1991). The verge were rndomly olleted for the study (Methusel et l., length nd width were mesured from t lest 10 00). ooysts to determine the size. Ooyst shpe nd olor Smple size determintion ws bsed on the ws lso reorded for eh reovered positive ses. ssumption of the possible prevlene rte of the Clibrtion of the mirosope objetive lens ws done disese reorded in other ples nd 15% expeted bsed on the proedures desribed by Conwy nd prevlene rte ws onsidered from previous MKenzie (1991). reserhers. The formul pplied to lulte smple The sporultion time of the ooysts ws determined t size ws the formul for simple rndom smpling o 9-30 using the tehnique desribed by Conwy nd method nd the study onsidered 95% level of MKenzie (1991). The sporultion time ws onsidered signifine (Thrusfield, 1995). when 90% of the ooysts were sporulted. Study design: The study design onsists of ross Gross lesion exmintion nd lesion sores: During setionl study to determine the prevlene of 18-4 hours sty of hiken in the lbortory nte oidiosis in lol strin nd Rhode Islnd Red breed mortem linil ondition of eh bird ws reorded. The hiken nd to identify the prevlent Eimerin speies in hiken ws euthenized by ervil dislotion using the the study re. Questionnire survey ws lso tehnique desribed by Znder (1978). The onduted to ollet informtion from frmers nd gstrointestinl trt ws grossly exmined refully. Adm poultry frm regrding the generl ondition The intestinl portions were divided into 4 setions, the bout poultry prodution nd disese problems in the upper prt (duodenum nd jejunum), the middle prt study re. (ileum), lower prt (distl ileum nd retum) nd el 5

3 Gri et l.: Poultry Coidiosis Tble 1: Clinil nd sub-linil oidil infetion ses Smples Sub- Totl positive (%) of (%) of 95% C I No Breed exmined Clinil linil ses linil positive ses linil (%) 1 Lol RIR b Totl Men vlues within olumn followed by different lower se supersript re signifintly different (p<0.05). Tble : Frequeny detetion of fel ooysts in lol strin hikens nd Rhode Islnd Red breed Mng Smp. Positive Clinil Prev C I of prev. Men C I of No Division Ctegory system exmined smp ses rte% rte% OPG± SE OPG 1 Breed LSC F-r ± b b RIR D-l ± Sex Mle ± Femle ± Men vlues within olumn followed by different lower se supersript (-d) re signifintly different (P < 0.05). Mng - Mngement, F - r = Free rnge, Smp - Smple, D - l = Deep litter, Prev - Prevlene, RIR - Rhode Islnd Red, OPG - Ooyst per grm, LSC - Lol Strin Chiken. pouhes. Intestinl gross lesions in ny prt of the setions were grded from 0 to 4 bsed on lesion sore key (Conwy nd MKenzie, 1991). The lesion sore zero represents bsene of lesion nd lesion sore four is for very severe intestinl /el muos lesion nd ftl ses. The lotion of the lesion ws reorded; intestinl ontents from the respetive setions were tken nd duplite muosl srpping smers mde from eh setion of the intestine. Sttistil nlysis: The ssoition of ooyst ount per grm fees between the two genotype hiken nd sex ws omputed by hi-squre test. The men Ooyst Per Grm ount, prevlene nd onfidene intervl in both genotype hikens were lulted using Stt-7 (Stt- 7, ). The p-vlue for sttistilly nlyzed dt ws onsidered signifint different t P<0.05 probbility level (Methusel et l., 00). Results Questionnire survey: Poultry mngement in the rurl re is free rnging nd hiken feed by svenging round the house with osionl erel nd food residuls supplement. More thn 75% respondents indited tht poultry prodution nd inome generted from poultry prodution in the rurl ommunity is the mjor inome soure for femles nd hildren. Disese problems in trditionlly mnged hiken re very importnt nd more thn 90% interviewees responded s medium to high rnk for disese problems. Although frmers hve their own lol nmes nd wys of identifying poultry diseses, the most frequent disese they omplin bout (>75%) ws dirrhe. The other observtion ws the sesonl ourrene of dirrhe nd more thn 85% frmers hve lerly desribed the olor of fees. More thn 75% of the respondents desribed tht bloody dirrhe predominntly ppered during wet seson thn hlky, yellow or green dirrhe. This observtion might be more inditive of the ourrene of oidiosis. Moreover, the publi nd privte veterinry servie enters hve no nti oidil drugs nd other mediments used for poultry diseses. More thn 80% frmers hve experiene of brooding nd rering hiks during dry seson. Potentil risk ftors for oidiosis: In free-rnging lol hikens, non-seletive piking behvior during feeding n expose hikens to infetion. Age group, high moisture onditions tht fvorbly influene ooyst sporultion nd development to the infetive stge were the potentil risk ftors. However, in Rhode Islnd Red breeds tht were kept under intensive deep litter system, the potentil risks observed from frm ssessment through questionnire were ge groups, prodution systems, flok size, moisture level in the poultry house nd level of bioseurity. Clinil oidiosis: In the urrent study, hiken tht showed depression, ruffled fether, dirrhe nd/or blood mixed droppings were reorded s linil ses. The results of linil nd sub linil infetion re shown in Tble 1. The number of linil ses in Rhode Islnd Red breed nd lol strin hikens ws not signifintly different. Clinil oidiosis detetion between mle nd femle ws lso not signifintly different in both genotype hikens. Quntittive nd qulittive fel exmintion: The prevlene of oidil infetion nd Ooyst Per Grm ount in lol strin nd Rhode Islnd Red hiken is shown on Tble. The frequeny ourrene of the oidil infetion in the Rhode Islnd Red breed ws signifintly higher thn the lol strins (Chi = 4.6; p <0.05). The Ooyst Per Grm ount in Rhode Islnd Red breed ws lso signifintly higher thn the lol strin hiken (Chi = ; p < 0.001). However, the frequeny ourrene of oidil infetion nd Ooyst Per Grm ount between mle nd femle ws not sttistilly signifint. The ssoition of linil se ourrene with Ooyst Per Grm ounts ws highly signifint in both genotype hikens (Chi = 106.8; p < 0.001). 53

4 Gri et l.: Poultry Coidiosis Tble 3: Coidil speies investigted in the study re nd their identifition hrteristis Speies identifition No hrters E. tenell E. netrix E ervulin E. mxim E mitis 1 Av. Ooyst length (µm) Av. Ooyst width (µm) Shpe index Frequeny ourrene Ooyst shpe Ovoid Oblong ovoid Ovoid Ovoid Sub-spheril 6 Sporultion (Hrs) t Site of ourrene Ceum Mid intestine Upper intestine Mid intestine Upper intestine in the intestine (Jejunum nd ileum) (Duodenum) (Jejunum nd ileum) (Duodenum Jejunum) 8 Pthologil Hemorrhge Bllooning, White round Bllooning, petehil. no, pprent lesion lesions indued & bleeding Bleeding, white olonies, hemorrhge, muoid in host intestine thikening plques & thikening streks & muoide exudtes & thikening of el wll of int. wll exudtes of int. wll Coidil speies identified in this study were E. tenell, the middle intestine on both sides from yolk s E. ervulin, E. netrix, E. mxim nd E. mitis in divertiulum, whih ws not the se in E. mxim. E. desending order of their ourrene. Mixed infetions ervulin usully ourred in the duodenl loop were the predominnt se, whih ounts for 45 hrterized by muoid exudtes in intestinl ontent; mixed infetions. The mjor proportion of mixed white spots were usully evident from the serosl side infetions mounting to more thn 55.6% ws onsisted nd eroded muosl membrnes. of E ervulin s member of the mixed infetion. E. The totl number of hiken in whih intestinl lesions netrix with E. ervulin nd E. mxim with E. were sored bove zero ws 98 (61%) in lol strin nd ervulin hve ourred in the highest mixed infetion 5 (81%) in Rhode Islnd Red breed. The frequeny frequeny. E. mitis ws the first dignosed speies of detetion of lesions in Rhode Islnd Red ws oidi in this study in Ehiopi nd reovered from the signifintly higher thn it ppered in lol strin smples olleted from Adm poultry enter. It ws the hikens (p < 0.05). The detetion of intestinl lesions smllest in size s ompred to others nd sub hd signifint ssoition with the ourrene of spheril shpe. The size nd olor of most oidil linil oidiosis (Chi = 17.38; p < 0.001). Moreover, speies re overlpping to identify bsed on their lesion sore showed signifint ssoition with Ooyst morphologil feture exept for E. mxim, whih hs Per Grm ounts in both genotype hikens (Chi = the lrgest size nd brown red olor. The verge length 89.7, p < 0.01). Lesion sore between mle nd femle nd width of eh speies nd their identifition ws not signifintly different. Mirosopi exmintion hrteristis re shown in (Tble 3). Most of intestinl muos srpping ws lso mde in oidil speies were restrited to speifi prediletion ddition to gross lesion grding to observe different sites in the intestine. However, E. ervulin nd E. developmentl stges of oidi in the muos. mxim were found to oupy the most proportion of the smll intestine thn other speies. Ooyst sporultion time for E. ervulin nd E. mitis were shorter (18 hours) s ompred to other speies. E. tenell nd E. netrix hd similr sporultion time of bout 0 hours nd E. mxim took lmost 36 hours o (Tble 3) for sporultion t 9-30 C. Gross lesions: Post mortem exmintion is the best method for dignosis nd speies identifition. The site of their ourrene nd hrteristi lesions produed by speifi Eimeri speies were used for identifition of the speies (Tble 3). E. tenell indued hemorrhge, thikening of the muos, lotted blood nd el ores in the eum depending on the mgnitude of infetion nd durtion of the infetion. In some ses onurrent infetions with bteril enteritis obsured the oidil lesions in duodenum nd eum. E. netrix nd E. mxim usully shred similr intestinl lesions. Lesions in E. netrix were more severe with bleeding nd whitish plques seen in Disussion Generlly, in trditionl poultry prodution system, the input required is miniml nd is onsidered s seondry to other griulturl tivities by the smllholder frmers. Housewives nd hildren re usully responsible to undertke poultry prodution round the homested. Sine these soil groups usully sty longer round the home, they n esily look fter the hiken. The inome obtined from poultry prodution my lso be most essible soure of inome during need of sh for women nd youths. Thus, from this point of view, poultry prodution my ddress the soil nd eonomil problems of gender issues nd improve the inome soure nd long-term eonomi potentil of women in the rurl ommunity. Indigenous knowledge of frmers on poultry oidiosis might not be very speifi. Nevertheless, they hve keen wreness regrding the risk ftors for the ourrene of the disese nd they desribe the disese bsed on the linil signs. The urrent observtion showed tht 54

5 Gri et l.: Poultry Coidiosis publi nd privte veterinry servies overlook the helth fvor its dominne ourrene in onfined prodution impt on poultry prodution nd no drugs nd system. Due to this ft Reid (1978) hs stted tht the biologil preprtions for poultry were vilble in their signifine of this speies s pthogen hs stok. Therefore, frmers pply their own indigenous inresed stedily within the reent yers in lrge poultry prties to tret nd ontrol hiken diseses, whih estblishments. Mixed infetions were frequently my not be usully effetive. The mgnitude of the enountered ounting for 45 mixed infetion. disese problem bsed on the frmer s response ws Lesion sore showed signifint ssoition with highly menble to pproprite tehnil interventions to linil oidiosis nd Ooyst Per Grm detetion inrese the prodution nd produtivity of this resoure. frequeny (p < 0.001, p < 0.01 respetively). This my be The prevlene of oidil infetions in the lol strin explined tht hiken tht hd lesions my more likely hikens in this study ws higher thn in previous mnifest linil disese nd lso shde lrge mount findings (Ashenfi et l., 004). The limti onditions, of ooysts in droppings (Methusel et l., 00). Thus, gro-eologil set-up nd lk of dequte informtion the lesion sore in Rhode Islnd Red breed ws on the subjet my be ttributed to the vrition in the signifintly higher thn lol hiken (p < 0.05) nd tht mintenne of the disese. The reltively wet limte my be the mirror refletion with the frequeny detetion nd ooler tempertures in the high nd mid ltitudes of of fel ooyst in the deep litter mngement system. the study re my be more fvorble for the ourrene Lesion sore in lol strin hiken ws usully of oidiosis. The finding my onsolidte the onfused or overlpping with the lesions produed by importne of oidiosis in the indigenous hiken. gstrointestinl prsites nd enteri infetious The frequeny ourrene of oidil infetion in Rhode diseses. Thus, the lesion sore prmeter my be Islnd Red breed ws signifintly higher (p < 0.05) thn ffeted nd not relible to indite the level of infetion the lol strin nd this ould be due to mngement nd the pthogeniity of oidil speies involved when system nd breed ftor. The higher Ooyst Per Grm superimposed with other infetions in the lol strin ount in Rhode Islnd Red breed n be relted with the hikens. E.ervulin nd E. mxim oupied muh higher frequeny ourrene of oidiosis in the deep greter re beyond the typil restrited sites of their litter system due to reltively higher ooyst umultion speies ourrene. This tendeny my be explined in the deep litter. The mount of ooyst dishrged from tht the merozoites re being rried by the peristlti infeted hiken depends on the dose of ooysts nd nti peristlti wves of the intestine beyond lredy ingested nd the immunologil sttus quired from infeted res in hevy infetion ses (Willims, 001). pre-exposure (Bumsted et l., 1991; Willims, 001). The ourrene of sub-linil oidiosis ws Thus, the hnes of the hikens to pik-up lrge signifintly higher thn linil oidiosis in both numbers of sporulted ooyst n be more likely in the genotype hiken nd mngement systems. The birds Rhode Islnd Red kept in deep litter mngement thn might hve developed immunity to the trikle infetions the lol strin hikens. The results of this study re quired from the environment nd mintin the stte of onsistent with the finding in lrge nd smll-sle deep blne to the infetion in the form of sub-linil litter rering systems (Methusel et l., 00). However, disese. The effet of sub-linil oidiosis on the ourrene of oidiosis ws not signifintly ffeted prodution performne of hiken nd its eonomi by sex. This indites tht there ws no signifint signifine should be further studied. nturl resistne vrition in reltion to the sex (Pinrd- Coidil infetion in deep litter mngement ws Vn Der Ln et l., 1998). signifintly higher thn in the free-rnging system. This The most eonomilly importnt speies of oidi E. showed tht mngement system plys gret role in tenell, E. ervulin, E. netrix nd E. mxim were the epidemiology of oidil infetion. However, the found in this study, whih is inongruent with the observed high prevlene rte of oidiosis in the previous reserhers reports (Mthusel et l., 00; indigenous hiken showed tht it is one of the Ashenfi et l., 004). Nevertheless, E. mitis ws the first eonomilly importnt diseses, whih deserve dignosed speies of oidi in this study in Ethiopi pproprite prevention nd ontrol mesures. bsed on morphologil nd other hrteristis from the smples olleted from Adm Poultry Center. Further onfirmtion of the identity of this speies in the free rnging hiken my be required in the future. The distribution of oidil speies in free-rnging hiken nd under intensive mngement ws not signifintly different. However, E. ervulin ws the most dominnt speies ourring in the intensive deep litter system, whih is in greement with the findings of Methusel et l. (00). The higher bioti potentil of this speies my Aknowledgement The uthors would like to knowledge the finnil support of the Offie of the Shool of Grdute Studies nd Reserh progrms Addis Abb University. We would like to express our thnks to Agriulturl Development Bureu of Oromi Regionl Stte nd Debre Zeit Poultry Reserh Division stff of EARO for their support during reserh work. Our speil thnks go to Dr. Hilu Wondimu nd the stff of Asell Regionl 55

6 Gri et l.: Poultry Coidiosis Veterinry Lbortory for their ssistne during the Methusel, S.K., G. Tilhun, H.M. Hfez nd M. reserh work. We re highly thnkful to Adm Poultry Breeding nd Multiplition Center for their oopertive spirit to supply us with Rhode Islnd Red breed hiken. Referenes Almrgot, J., Avin Pthology of Industril Poultry Frms in Ethiopi. In: Proeeding of First Ntionl Livestok Improvement Conferene: Institute of Agriulturl Reserh (Ed.) Februry, 1987, Addis Abb, Ethiopi. Ashenfi, H., S. Tdesse, G. Medhin nd M. Tibbo, 004. Study on Coidiosis of Svenging Indigenous Chikens in the Centrl Ethiopi. Trop. Anim. Hlth. Prod. (in press). Bumsted, N., B.M. Millrd, P. Brrow nd J.K.A. Cook, Geneti Bsis of Disese Resistne in Chikens. In: Owen, F.B. nd Ax ford, R.F.E. (Eds.): Breeding for Disese Resistne in Frm Animls. C.A.B. Interntionl, pp: Conwy, D.P. nd M.E. MKenzie, Poultry Coidiosis. Dignosti nd Testing Proedures, nd Edn. Pfezer In., The Netherlnd, pp: 7-14, Grt, E.A.M., H.W. Ploeger, A.M. Henken, G. De Vries Reilingh, J.P.T. Noordhuizen nd P.N.G. Vn Beek, Effets of Initil Litter Contmintion Level with Eimeri ervulin in Popultion Dynmis nd Prodution Chrteristis in Broilers. Vet. Prsitol., 65: 3-3. Kinung hi, S.M., T. Gethew, M.H. Hfez, W. Moges, K. Moses, G. Mthis nd P.O.B. Mximillin, 004. Assessment of Eonomi Impt Cused by Poultry Coidiosis in Smll nd Lrge Poultry Frms in Debre Zeit, Ethiopi. Int. J. Poult. Si., 3: Lillehoj, H.S. nd J.M. Trout, A Review of Reent Advnes on Immunity nd Vine Development. Avin Pthol., : MAFF, Ministry of Agriulture, Fisheries nd Food. Mnul of veterinry Prsitologil Lbortory Tehniques. Tehnil Bulletin No. 18, nd Edn. Her Mjesty s Sttionry Offie, London, pp: Woldemeskel, 00. Studies on Poultry Coidiosis in Different Prodution Systems in D/Z nd Surrounding res, Ethiopi. Bull. Anim. Hlth. Prod. Afr., 50: Nsser, M., Orl New Cstle Disese Vintion Trils nd Studies on Newstle Disese in Ethiopi. Fulty of Veterinry Mediine, Free University of Berlin, Debre Zeit/Berlin, Ms Thesis. Pinrd - Vn Der Ln, M.H., J.L. Monvoisin, P. Pery, N. Hmet nd M. Thoms, Comprison of Outbred Lines of Chikens for Resistne to Experimentl Infetion with Coidiosis (Eimeri tenell). In: Breeding nd Genetis. Poult. Si., 77: Reid, W.M., Coidiosis. In: Hofstd, M. S., Clnek, B.W., Helmboldt, C.F., Reid, W.M. nd Yoder, Jr., H.W. (Eds.), Diseses of Poultry, 7th Edn. USA, Iow Stte University Press. Ames,Iow, pp: Soulsby, E.J.L., 198. Helminths, Arthropods nd Protozon s of Domestited Animls, 7th Edn. Billiere Tindll, London, pp: 630. Stt-7, Interooled Stt-7 Sttistil Dt Anlysis. Stt Corportion, College Sttion, Texs USA. Thrusfield, M., Veterinry Epidemiology, nd Edn. Blkwell Si. Ltd, UK., pp: Willims, R.B., 001. Quntifition of the Crowding Effet during Infetions with the Seven Eimeri speies of the Domestited Fowl: It s Importne for Experimentl Designs nd the Prodution of Ooyst Stoks. Int. J. Prsitol., 31: Znder, D.V., Priniples of Disese Prevention, Dignosis nd Control. In: Hofstd, M.S., Clnek, B. W., Helmboldt, C.F., Reid, W.M. nd Yoder, Jr., H.W. (Eds.). Diseses of Poultry, 7th Edn. Iow Stte University Press/Ames, Iow, USA., pp: