757 Asan-Aust. J. Anm. Sc. Vol., No. : 757-76 December.ajas.nfo http://dx.do.org/.57/ajas.. Effect of Aflatoxn on Feed Converson Rato n Brolers: A Meta-analyss R. Umaya Suganth*, K. P. Suresh and R. Parvatham Natonal Insttute of Anmal Nutrton and Physology, Bangalore, Karnataka 56, Inda ABSTRACT: Aflatoxns are natural contamnants of poultry feeds and feed ngredents and cause lver damage, mmunosuppresson, reducton n performance and mortalty n brolers. A number of studes have been carred out to study the effects of aflatoxn on feed converson rato n brolers. The results on feed converson rato of research artcles n brolers fed th aflatoxn from frst day of age to sx eeks of age ere compled and ere subjected to meta-analyss. Ch-square test and Tau (heterogenety co-effcent) ere appled to test for sgnfcance of heterogenety of studes. To ntegrate results, fxed effect model by Inverse Varance method (IV method) as used hen heterogenety as nsgnfcant and otherse random effect model by DerSmonan and Lard Method (DL method) as used. The results of meta-analyss shoed that the adverse effect of aflatoxn on feed converson rato at the end of frst eek as neglgble, second eek as medum and thrd to sx eeks as very large. (Key Words : Aflatoxn, Feed Converson Rato, Brolers, Meta-analyss) INTRODUCTION Mycotoxns are toxc secondary metaboltes of certan fung and cause llness or death hen ngested by anmals or human bengs (Qaz and Fayyaz, 6). One of the most toxc group of mycotoxns are the aflatoxns (AFs), produced by the fung, Aspergllus flavus and Aspergllus parastcus. Aflatoxns ere frst dscovered n 96 n England after the outbreak of Turkey-X-dsease durng hch mllon turkey poults ded n England due to the toxn (Blount, 96). They are natural contamnants of poultry feeds and feed ngredents, maze, sorghum, pearl mllet, rce, peanut meal and cottonseed meal (Reddy et al., ). Contamnaton of feeds and feed ngredents may occur at any tme before and after harvest and dryng, durng storage, processng and manufacturng. Chemcally, aflatoxns are a group of dfuranocoumarn dervatves and the major types of aflatoxns are aflatoxn B (AFB), aflatoxn B (AFB), aflatoxn G (AFG) and aflatoxn G (AFG). Among the aflatoxns, AFB as dentfed to be the most toxc and most prevalent compound, folloed by G, B and G th decreasng toxcty (Murphy et al., 6). Aflatoxn ntake n brolers s assocated th lver * Correspondng Author : R. Umaya Suganth. Tel: +9-8- 57, Fax: +9-8-57, E-mal: suganthmanmaran@ gmal.com Receved May, ; Accepted June 9, damage, poor performance, mmunosuppresson and mortalty. Aflatoxn toxcty n poultry s also assocated th bochemcal, hematologcal, reproductve and pathologcal changes (Ortatatl and Oguz, ). Some of the metaboltes formed durng the metabolsm of AFB are transmtted to edble anmal products, lver, muscle ((Bntvhok and Davtyananda, ) and eggs, hch exert mmunosuppressve, embryotoxc and teratogenc effects (Celk et al., ; Olvera et al., ). Besdes affectng the health of brds and consumers, aflatoxns also cause economc losses to poultry ndustry. The Councl for Agrcultural Scences and Technology recorded an annual crop losses of $9 mllon due to mycotoxn contamnaton and addtonal losses of $66 mllon n efforts to prevent or reduce contamnaton (Rchard and Payne, ). In poultry, partcularly n brolers, a number of studes on the effect of aflatoxns on Feed Converson Rato (FCR) have been carred out by researchers orldde. Hoever a precse estmate of the effect of aflatoxns on the FCR durng -6 eeks of age of brolers s not avalable. Hence the present study as undertaken to understand and reveal the effects of aflatoxns on FCR durng dfferent eeks of broler producton, by meta-analyss. MATERIAL AND METHODS The data of research artcles nvolvng 5 studes
758 Suganth et al. () Asan-Aust. J. Anm. Sc. ():757-76 (Daz and Sugahara, 995; Kubena et al., 998; Oguz et al., ; Oguz and Kurtoglu, ; Verma et al., ; Celk et al., 5; Abousad et al., 7; Modrsane et al., 8; Kermanshah et al., 9; Shaban et al., ) ere selected for meta-analyss. The results on feed converson rato n brolers fed th aflatoxn from frst day of age to sx eeks of age ere compled and ere subjected to meta-analyss to determne the effect of aflatoxn on FCR thout any bas. Gven a vast quantty of heterogeneous lterature, the type of tems that ere collected ncludes, the characterstcs on the report of the study (such as author, year and source), the study tself, research desgn (duraton of exposure, treatment assgnment mechansm or samplng mechansm) and the effect sze (sample sze, nature of outcome, estmates and standard error). The method appled for metaanalyss as smlar to that descrbed earler (Mondal et al., ; Suresh et al., ). The unt of data for meta-analyss as mean and standard devaton reported n the studes. The data ere extracted for control and expermental groups n the prespecfed proforma. The follong ere the ncluson crtera appled to select the study ). Research conducted on brolers and anyhere n the orld; ). Only studes presented n Englsh and ).Those studes th complete nformaton s avalable. The effect sze hch s the standardzed mean dfference of control and expermental settng s defned by Cohen s g and s computed as Ye Yc g ( ), here Y e s mean of the Sp expermental group, Y c s the mean of the control group and Sp s the pooled standard devaton th ( ne ) se + ( nc ) sc Sp, Snce g s based estmator ne of the populaton effect sze and hence g has to be multpled by correcton term j here m m n e, The resultng effect sze statstc s as follos d g( ) and the varance of d s m ne d σ +. n e nc ( ne ) After testng for sgnfcance of heterogenety of studes based on ch-square test and Tau (heterogenety coeffcent), fxed effect model or random effect model ere selected for ntegratng the results. When heterogenety as nsgnfcant, fxed effect model by Inverse Varance method (IV method) as used th zero heterogenety coeffcent, otherse a random effect model by DerSmonan and Lard Method (DL method) as used. Random effect model allos the study varaton by co-effcent of heterogenety to some extent hle ntegratng results and n the present study, the maxmum Tau alloed as so as to avod the larger heterogenety among the studes (Glass, 976; Eugene et al., ; Sauvant et al., 8). Inverse-Varance method The Inverse-Varance Method (IV method) as used to pool ether bnary, contnuous or correlaton data. Ths approach has de applcablty snce t can be used to combne any estmate that has standard error avalable. The effect sze or mean are combned to gve a pooled estmate (denoted by θ) by calculatng eghted average of the treatment effects from the ndvdual studes as gven belo. θ IV θ Where the eghts are calculated as, SE( θ ). That s, the eght for the th study s equal to ts precson of the estmate.. The standard error of θ IV s gven by, SE(θ IV ) The heterogenety statstc (denoted by Q ) s gven by, Q ( θ θ IV ) The Q follos ch-square dstrbuton th (k-) degrees of freedom, here k s the number of studes ncluded n the meta-analyss. DerSmonan and Lard method The DerSmonan and Lard method (DL method) of meta-analyss s based on the random effects model. Under the random effects model, the assumpton of common effect s relaxed, and the effect sze or mean θ are assumed to have a normal dstrbuton th mean θ and varance τ. The usual DL estmate for τ s gven by, τ Q ( k ) here Q s the heterogenety statstc, and the eghts are calculated as n the IV Method, and k s the number of studes. The τ s set to zero f Q <(k-). In ths approach, the eghts for each study effect sze are as gven
Suganth et al. () Asan-Aust. J. Anm. Sc. ():757-76 759 belo. SE( θ ) +τ The pooled estmate s gven by, θ DL θ Wth standard error, SE(θ DL ) The heterogenety statstc and ts test of sgnfcance s as gven n the IV method. RESULTS Meta-analyss on the effect of feedng aflatoxn durng day one to sx eeks of age on FCR n brolers Fgure depcts the meta-analyss results on effect of feedng aflatoxn on FCR at st eek, nd eek, rd eek, th eek, 5 th eek and 6 th eek of age of brolers. The results 8 7.8..8 6 Effect sze(d).5..5..5..5.8.... Study St udy St udy St udy St udy 5 St udy 6 Combned Week -FCR Effect sze(d) - - -..5.89.6.78.57 Study Study Study Study Study 5 Study 6 Study 7 Study 8 Combned -.75 -.9 Week -FCR 9. Effect sze(d) 8 6 -..55.76.8. Study Study Study Study Study 5 Study 6 Comb ned -.6 Effect sze(d) 5 -.6. 5.7 8.6.7.8.8..8 -.7 -.5 S t udy S t udy S t udy S t udy S t udy 5 S t udy 6 S t udy 7 S t udy 8 S t udy 9 S t udy S t udy C ombned -5.58 Week -FCR Week -FCR Effect sze(d).5.5.5.5.5.99.5.69.77.9.59.5 Study Study Study Study Study 5 Study 6 Comb ned Effect sze(d) 8 7 6 5 7. 6.6.9.8..79..5.66.6.8 S t udy S t udy S t udy S t udy S t udy 5 S t udy 6 S t udy 7 S t udy 8 S t udy 9 S t udy C ombned Week 5-FCR Week 6-FCR Fgure. Effect of aflatoxn on feed converson rato n brolers durng -6 eeks of age.
76 Suganth et al. () Asan-Aust. J. Anm. Sc. ():757-76 ere presented on effect sze hch s the standardzed dfference of means of control and expermental groups. Effect reflects the effect of aflatoxn on FCR.e., hgher the effect sze, more the toxc effect on FCR. The varaton due to dose, settng, brds, breed and laboratory ere controlled as effectve sze and estmated by random effect method. Frst eek : Among the sx studes subjected to metaanalyss, four shoed no effect or a neglgble effect (effect sze d<.) on FCR by feedng aflatoxn from frst day to one eek of age hereas to other studes shoed a small effect (.<d<.5). Independent analyss of the results dd not confrm the effect of aflatoxn. On the other hand, the meta-analyss of random effect model by DL method shoed postve results but th neglgble effect (d.). Second eek : At to eeks of age, feedng aflatoxn to brolers exhbted neglgble effect on FCR n fve studes (d<.) and a small effect (.<d<.5) n one study. In contrary to these results, to other studes revealed a very large effect (d>.) of aflatoxn on FCR. But the metaanalyss of random effect model by DL method shoed postve results th a medum effect (d.57) of aflatoxn on FCR. Thrd eek : Meta-analyss of fve of the sx studes selected shoed a neglgble effect (d<.) on FCR n brolers fed aflatoxn for three eeks hereas one study shoed a small effect (.<d<.5). But the results of meta-analyss of random effect model by DL method shoed postve effect of aflatoxn on FCR that as very large (d.76) and adverse. Fourth eek : In the fourth eek, vared effect of aflatoxn on FCR as observed. Among eleven studes evaluated, nne exhbted a neglgble effect (d<.). A small effect (.<d<.5) as observed n one study and a very large effect as observed n other study (d>.). Hoever, the meta-analyss of random effect model by DL method performed, shoed postve effect of aflatoxn on FCR that as very large (d 8.6) and hghly adverse. Ffth eek : Independent analyss of the results of all the sx studes subjected to meta-analyss shoed neglgble effect of aflatoxn on FCR (d<.). Hoever, the metaanalyss of random effect model by DL method performed exhbted postve effect of aflatoxn on FCR and the effect as observed to be very large (d.77). Sxth eek : Independent analyss of ten studes at sx eeks of age of brolers revealed neglgble effect of aflatoxn on FCR (d<.). But the meta-analyss of random effect model by DL method performed shoed postve effect of aflatoxn on FCR and the effect as very large (d.79). DISCUSSION Meta-analyss s a rapdly expandng area of research. It refers to the statstcal analyss of large collectons of results from ndvdual studes for the purpose of ntegratng the fndngs and t s a quanttatve study desgn used to systematcally assess prevous studes to derve the conclusons about the body of research. Outcomes from meta-analyss may nclude a more precse estmate of the effect of treatment or the rsk factors for dsease or condton than any ndvdual studes contrbutng to the pooled analyss. Identfcaton of the source of varaton n responses or heterogenety of group of studes and generalsng of responses can lead to a more effectve treatment or modfcaton of management. Examnaton of heterogenety s perhaps the most mportant task n metaanalyss. Meta-analyss places a less emphass on sgnfcance testng and larger emphass on determnng the magntude and precson of an effect of nterest. The poultry ndustry s one of the fastest grong sectors and a major problem n t s the occurrence of aflatoxns n feed (Calder, 7). In the poultry ndustry, any factor that affects the feed converson rato of brds affects the economc gan. Hence the present study s focused to meta-analytcally study the effect of feedng aflatoxn on feed converson rato n brolers. The studes selected for meta-analyss ere conducted usng dfferent doses of aflatoxns rangng from.5 ppm to 5. ppm. Aflatoxn feedng at.6 ppm dose (Daz and Sugahara, 995) s shon to decrease FCR at the end of frst eek of age. Contrary reports ndcatng no change n FCR by feedng aflatoxns (.5-. ppm) n det for eek are also avalable (Oguz and Kurtoglu, ; Celk et al., 5). Hoever, the meta-analyss shos the postve effect hch s neglgble and ths could be attrbuted to feed ntake and eght gan as FCR may depend on feed ntake and eght gan. Oguz and Kurtoglu () dd not sho any reducton n FCR after feedng.5 ppm aflatoxn B for eeks. Hoever, meta-analyss shos a medum effect hch reflects the toxcty nduced by aflatoxn. The reports on effect of aflatoxn on FCR at three eeks of age of brolers are contrary. A sgnfcant ncrease n FCR by 7% to % s shon n chcks fed a det contanng.5 ppm aflatoxn (Huff et al., 986; Oguz, 997) and 5. ppm aflatoxn (Kubena et al., 998) from to days of age, hch n turn ndcates the adverse effect of aflatoxns on feed utlzaton. In contrary to the above fndngs, Oguz and Kurtoglu () dd not observe any sgnfcant dfference n FCR n brds fed.5 ppm up to three eeks of age. In the present study, meta- analyss ndcates very large adverse effect of aflatoxn on FCR. Shaban et al. () demonstrated a reducton n FCR at the end of eeks n brds fed th.5 ppm aflatoxn, hch s n agreement th earler studes (Verma et al., ; Pandey and Chauhan, 7) and meta-analyss ndcates adverse effect hch s very large. Verma et al.
Suganth et al. () Asan-Aust. J. Anm. Sc. ():757-76 76 () found a sgnfcant reducton n FCR of brds fed. ppm and. ppm of aflatoxns at four and seven eeks of age, suggestng an nverse relatonshp beteen aflatoxn concentraton n feed and FCR. Aflatoxn levels as lo as. ppm for 5 eeks or 8 eeks could affect the FCR n brds (Oguz et al., ). Even 5 ppb aflatoxns n feed could be harmful to brds f there are subclncal dseases. Many a tme, under the feld condtons, brds are exposed to lo levels of aflatoxns; chronc exposure of poultry to aflatoxns thout clncal symptoms s a major concern n the poultry ndustry as the dagnoss and treatment are dffcult. Celk et al (5), recorded reducton n FCR n chcks fed dets supplemented th. ppm aflatoxn B for 6 eeks, and ths s n agreement th earler report of Allameh et al. (5). Kermanshah et al. (9) shoed that.5 and. ppm aflatoxn dd not negatvely nfluence feed converson rato even after sx eeks of feedng and Edrngton et al. (997) has reported smlar results. The meta-analyss ndcates very large effect of aflatoxn on FCR hch reflects the adverse effect of aflatoxn. The manfestaton of chronc or acute toxcoss n brolers depends on stran, duraton of exposure and rate of metabolsm of aflatoxn to less toxc metaboltes (Kermanshah et al., 9; Shaban et al., ). The adverse effects of aflatoxns are due to anorexa, lstlessness, mpared lver functons and proten/lpd utlzaton mechansms. Aflatoxn B may cause a dose-dependent nducton or nhbton of lver mxed functon oxygenase actvtes, hch may affect the metabolsm of endogenous and exogenous substrates by lver (Shaban et al., ). The reducton n actvtes of specfc enzymes nvolved n dgeston of carbohydrates, protens, lpds nuclec acds and the absorpton of essental nutrents by aflatoxn contamnated feed (Abousad et al., 7) contrbutes to reducton n feed effcency n brolers. CONCLUSION In concluson, the results of the present meta-analyss study ndcate adverse effect of aflatoxn on FCR and t s very large from thrd to sx eeks of age of brolers. Such nformaton s of mportance to all poultry farmers and the ndustry. REFERENCES Abousad, M. A., E. Roghan and E. M Honarmand. 7. The effcacy of varous addtves to reduce the toxcty of aflatoxn B n broler chcks. Iran. J. Vet. Res. 8:-5. Allameh, A., A. Safamehr, S. A Mrhad, M. Shvazad, A. M Abyaneh and A. Nader. 5. Evaluaton of bochemcal and producton parameters of broler chcks fed ammona treated aflatoxn contamnated maze grans. Anm. Feed Sc. Technol. :89-. Bntvhok, A. and D. Davtyananda.. Aflatoxns and ther metabolte resdues n chcken tssues from 5 parts ( provnces) of Thaland. Tha J. Hlth. Res. 6:7-5. Blount, W. P. 96. Turkey X dsease. J. Br. Turkey Fed. :5-6. Calder, P. 7. Indan anmal feed ndustry Expo. Feed Tech. 8-. Celk, I., H. Oguz, O. Demet, M. Boydak, H. H. Donmez, E. Sur and F. Nzamloglu.. Embryotoxcty assay of aflatoxn produced by Aspergullus parastcus NRRL 999. Br. Poult. Sc. :-9. Celk, S., Z. Erdogan, S. Erdogan and R. Bal. 5. Effcacy of trbasc copper chlorde (TBCC) to reduce the harmful effects of aflatoxn n brolers. Turk. J. Vet. Anm. Sc. 9:99-96. Daz, G. J. and M. Sugahara. 995. Indvdual and combned effects of aflatoxn and gzzerosne n broler chckens. Br. Poult. Sc. 6:79-76. Edrngton, T. S., L. F. Kubena, R. B. Harvey and G. E. Rottnghaus. 997. Influence of super actvated charcoal on the toxc effects of aflatoxns or T- toxn n grong brolers. Poult. Sc. 76:5-. Eugene, M., H. Archmede and D. Sauvant.. Quanttatve meta-analyss on the effects of defaunaton of the rumen on groth, ntake and dgeston n rumnants. Lvest. Prod. Sc. 85:8-9. Glass, G. V. 976. Prmary, secondary and meta-analyss of research. Educ. Res. 5:-8. Huff, W. E., L. F. Kubena, R. B. Harvey, V. M. Hagler, S. P. Sanson, T. D. Phllps and C. R. Creger. 986. Indvdual and combned effects of aflatoxn and deoxynvalenol (DON, vomtoxn) n broler chckens. Poult. Sc. 65:9-98. Kermanshah, H., A. R. Hazegh and N. Afzal. 9. Effect of sodum bentonte n brolers fed dets contamnated th aflatoxn B. J. Anm. Vet. Adv. 8:68-559. Kubena, L. F., R. B. Harvey, R. H. Baley, S. A. Buckley and G. E. Rottnghaus. 998. Effects of a hydrated sodum Calcum Alumnoslcate (T-bnd) on Mycotoxcoss n young broler chckens. Poult. Sc. 77:8-59. Modrsane, M., B. Mansoor, A. R. Khosrav, M. M. Kae, P. Khazraena, M. Farkhoy and Z. Masoum. 8. Effect of datomaceous earth on the performance and blood varables of brolers chcks durng expermental aflatoxcoss. J. Sc. Food Agrc. 88:66-6. Mondal, S., K. P. Suresh and S. Nand.. Endocrne profle of oestrous cycle of buffalo: A meta-analyss. Asan-Aust. J. Anm. Sc. :69-76. Murphy, P. A., S. Hendrch, C. Landgren and C. M. Bryant. 6. Food Mycotoxns: An Update. J. Food Sc. 7:5-65. Oguz, H. 997. The preventve effcacy of polyvnylpolypyrrolodone (PVPP) alone and ts combnaton th the other adsorbents nto broler feeds aganst aflatoxcoss. Ph.D. Thess, Unversty of Selcuk, Konya. Oguz, H. and V. Kurtoglu.. Effect of clnoptlolte on performance of brolers chckens durng expermental aflatoxcoss. Br. Poult. Sc. :5-57. Oguz, H., V. Kurtoglu and B. Coskun.. Preventve effcacy of clnoptlolte n brolers durng chronc aflatoxn (5 and ppb) exposure. Res. Vet. Sc. 69:97-. Olvera, C. A. F., E. W. Kobashgaa, T. A. Res, L. Mester, R.
76 Suganth et al. () Asan-Aust. J. Anm. Sc. ():757-76 Albuquerque and B. Correa.. Aflatoxn B resdues n eggs of layng hens fed a det contanng dfferent levels of the mycotoxns. Food Addt. Contam. 7:59-6. Ortatatl, M. and H. Oguz.. Ameloratve effects of detary clnoptlolte on pathologcal changes n broler chckens durng aflatoxcoss. Res. Vet. Sc. 7:59-66. Pandey, I. and S. S. Chauhan. 7. Studes on producton performance and toxn resdues n tssues and eggs of layer chckens fed on dets th varous concentratons of aflatoxn AFB. Br. Poult. Sc. 8:7-7. Qaz, J. I. and Z. Fayyaz. 6. Aflatoxn contamnated foods and health rsk perspectve for Pakstan populaton. Mycopathol. :7-. Reddy, D. V. R., T. K. Dev, S. V. Reddy, F. Walyar, M. A. Mayo, K. Rama Dev, R. Ortz and J. M. Jenne.. Estmaton of aflatoxn levels n selected n foods and feeds n Inda and Food safety management n developng countres. In: Proceedngs of the Internatonal Workshop, CIRAD-FAO, France. pp. -. Rchard, J. L. and G. A. Payne.. Mycotoxns: rsks n plant, anmal, and human systems. CAST. 99. Sauvant, D., P. Schmdely, J. J. Daudn and N. R. Perre. 8. Meta-analyss of expermental data n anmal nutrton. Anm. :-. Shaban, A., B. Dastar, M. Khomer, B. Shabanpour and S. Hassan.. Response of broler chckens to dfferent levels of nanozeolte durng expermental aflatoxcoss. J. Bol. Sc. :6-67. Suresh, K. P., S. Nand and S. Mondal. 9. Factors affectng the laboratory producton of buffalo embryos: A meta-analyss. Therogenol. 7:978-985. Verma, J., T. S. Johr, B. K. San and S. Ameena.. Effects of graded levels of aflatoxns, ochratoxn and ther combnatons on the performance and mmune response of brolers. Br. Poult. Sc. 5():5-58.