Statistical Modeling of Egg Weight and Egg Dimensions in Commercial Layers

Transcription

1 Interntionl Journl of Poultry Siene 6 (1): 59-63, 2007 ISSN Asin Network for Sientifi Informtion, 2007 Sttistil Modeling of Egg Weight nd Egg Dimensions in Commeril Lyers O.T.F. Aniknnd, O. Olutogun, A.O. Leigh nd L.A. Ajyi 1 Deprtment of Zoology, Lgos Stte University, Nigeri 2 Deprtment of Animl Siene, University of Idn, Nigeri Astrt: Egg weight nd dimensions of tle eggs from Hro hevy reed lyers in e humid tropis of Lgos, Nigeri were mesured, nd reltionships etween Egg Weight (EGGWT), Egg Leng (EGGLT), Egg Wid (EGGWD) nd Egg Shpe Index (SHPINDX) were studied. A totl of 2951 eggs otined from lyers in five different ge groups were smpled. Egg weight nd egg wid exhiited similr pttern in eir distriution ross e different ge groups, wi stedy inrese from ge group A (22-32 weeks), peked t ge group D (55-65 weeks) efore deline fterwrds. Egg leng onsistently inresed wi inresing ge of hen, while shpe index onsistently deresed wi inresing ge of hen. Correltion etween egg weight & egg leng, egg wid nd shpe index ws 0.78, 0.84 nd respetively, while e orreltion etween egg leng & egg wid nd shpe index ws 0.53 nd respetively, nd etween egg wid nd shpe index ws The fitted model of e study ws EGGWT = (EGGLT) (EGGWD) (SHPINDX). All oeffiients otined were signifint (P<0.05), however, it ws oserved t egg leng nd egg wid were etter preditors of egg weight when ompred to shpe index. Anlysis of vrine reveled t effets of ll ftors studied (ge group, egg leng, egg wid, shpe index nd egg leng x egg wid intertion) were highly signifint (P<0.01) on egg weight exept for shpe index whih ws signifint (P<0.05). Egg dimensions were good estimtors of egg weight. Key words: Egg weight, dimensions, sttistil model Introdution Poultry reeding is generlly eptle to people ll over e world nd provides n exellent soure of protein espeilly for poor rurl ommunities, euse it requires little pitl, lour nd lnd. Poultry irds re good onverters of feed into usele protein in met nd egg. The prodution ost per unit is low reltive to oer types of livestok nd e return on investment is high, us frmers need just smll mount of pitl to strt poultry. Also met produed is very tender, so it is pltle nd eptility to onsumer is high. Poultry hs short prodution yle (i.e. py k period) rough whih pitl is not tied down over long period. The egg of hiken is iologil struture intended y nture for reprodution nd it lso provides omplete diet for e developing emryo. However, in e developing ountries, egg is more ffordle y e ommon mn n oer soures of niml protein nd s suh is gives poultry more dvntge over oer livestok (Ojo, 2000; Okeke, 2000). Egg weight is n importnt egg trit, whih influene egg qulity s well s grding (Frooq et l., 2001). It is prmeter whih ould e determined out e egg wiout reking e egg (Wilson nd Surez, 1993; Frooq et l., 2003). The weight of n egg is diret proportion of lumen, yolk nd shell it ontins nd is vries signifintly etween strins of hen (Pndey et l., 1986) nd e hens ge ffets is proportion of yolk, lumen nd shell produed, us egg weight inreses wi hens ge, rehing plteu y e end of e lying yle (Dnilov, 2000). Egg leng is lso referred to s e height of e egg. It is e longest portion oserved on e externl surfe. The egg leng is lso referred to s e long order. Conversely, egg wid is e shorter portion of e egg. The dense mss of egg (yolk) is situted t e enter of e egg whih is lso responsile for e wideness of e wid. The wid of n egg is lso referred s e red or e short order (Gunlu et l., 2003). The reltionship etween egg weight, egg leng nd egg wid ws reported y Choprkrn et l. (1998). The shpe of irds egg is mtter of nturl onveniene rer n eseti onsidertion nd e overll shpe of n egg should e smoo in order to ssist in lying. Kimer (2005) investigted e height/wid rtio of irds eggs, proportion whih is more result of funtion n rtisti perfetion, while Pnd (1996) nd Gunlu et l. (2003) defined egg shpe index s e rtio of e short order reltive to e long order. It is erefore e ojetive of is study to estimte e sttistil mesures of weight, leng, wid nd shpe index of egg, investigte e reltionship etween e vriles, nd fit sttistil model for prediting weight of n egg using egg dimensions. Mterils nd Meods This study ws onduted t e Deprtment of Zoology, Lgos Stte University, Ojo-Lgos, Nigeri. The eggs used in is study were otined from ommeril 59

2 Aniknnd et l.: Sttistil modeling of egg mesurements poultry frm loted on e fringes of Lgos Stte, ordering Ogun Stte in e humid tropis of sou western prt of Nigeri, during e period of Novemer nd Deemer Experimentl nimls nd mngement: The eggs used in is study were lid y Hro lk strin of hiken whih were soured from e sme hery nd rised under similr mngement tehniques. The frm hd irds t different stges of ly. Dy old pullets were purhsed from reputle heries nd kept on litter till out 18 weeks efore ey re moved to e ttery ge. During e first four weeks of development, e hiks were proteted from old y pling eletri uls in eir pens, whih hs polyene sheets ted to e sides to provide wrm during rooding. During ly, e irds re fed twie dily wi ompounded rtion ontining 16% rude protein, oer onstituents of eir feed inludes vitmins, minerls nd mino id. Wter is provided d liitum. The irds re routinely vinted t ertin stges of development ginst diseses suh s Newstle, Gumoro, Coidiosis et. Egg olletion t frm ws usully done in e evening round 5.00pm, nd egg mesurements re done e next dy in e lortory. Experimentl design: A totl of one hundred trys of eggs were smpled. This omprises of twenty trys from eh of e five distint ge groups. For ese of omprison, e irds re lssified into five nominl groups sed on eir ges (Tle 1). Eh try holds 30 eggs. Despite e intent for lned design, some eggs were eliminted from e study due to eir physil stte (roken or rked), us, totl of 2,951 eggs were eventully used in e nlyses. Dt olletion nd sttistil nlyses: The eggs were identified nd leled y psting msking tpe wi pproprite identifition tg round e shrp end of e egg. Egg weight ws mesured using 0.0g sensitive digitl sle. This is done y gently pling e egg on e flt surfe of e sle ensuring t e sle is set to 0.0g efore mesurement. Egg leng nd egg wid of e egg were mesured wi eletroni digitl Vernier liper sensitive to 0.00mm. Shpe Index is estimted using Pnd (1996) formul; Shpe Index = [egg wid / egg leng] 100 All sttistil nlyses were done using S-Plus (2001) sttistil softwre. Desriptive sttistis nd si explortory nlyses were done using e summry sttistis su-routine of Tle 1: Age grouping of lying hens Age groups Age intervls (weeks) A B C D E e omputer progrm. Mesures otined inludes: minimum, mximum, men, numer of oservtion, stndrd devition, stndrd error of e men nd e onfidene limits t 95%. The reltionship mongst e four prmeters under study ws estimted using e liner orreltion proedures. Liner regression of e different vriles (egg leng, egg wid nd shpe index) on egg weight ws rried out. The model t desries e regression nlysis is given s: Where Y is e estimted Egg weight nd L, W nd S re e Leng, Wid nd Shpe index. Ftors ffeting e weight of eggs were studied nd e sttistil model desriing e nlysis of vrine is given s; Y = µ + A + L +W + S + (LW) + e ijklm i j k l jk ijklm Where Y ijklm = e oserved egg weight µ = popultion men A i = i fixed effet of ge group (I=1-5) L j = j ovrite of egg leng W k = k ovrite of egg wid S l = l ovrite of shpe index (LW) jk= intertion of egg leng y egg wid e ijklm = residul rndom error. Results Egg weight: The men egg weight for e omined ges in is study is 55.99±0.11g (Tle 2). The 95% lower onfidene limits of egg weight re 55.76, 49.54, 56.00, 56.46, nd 57.68g for e omined, group A,-E respetively. While e 95% upper onfidene limits re respetively 56.21, 50.34, 56.71, 57.56, nd Egg leng: The men egg leng for e omined ges in is study is 56.27±0.05mm (Tle 2). The 95% lower onfidene limits of egg leng re 56.17mm, 53.69mm, 56.00mm, 56.43mm, 57.06mm nd 57.23mm for e omined, group A, group B, group C, group D nd group E respetively. While e 95% upper onfidene limits re respetively 56.37mm, 54.03mm, 56.33mm, 56.86mm, 57.48mm nd 57.62mm. 60

3 Aniknnd et l.: Sttistil modeling of egg mesurements Tle 2: Mens ± Stndrd Errors for e Vriles Studied Age group (weeks) N Egg weight (g) Egg leng (mm) Egg wid (mm) Shpe index (%) A (22-32) ± 0.20 d 53.86±0.09 d 40.91± ±0.12 B (33-43) ± ± ± ±0.12 C (44-54) ± ± ± ±0.13 D (55-65) ± ± ± ±0.16 E (66-76) ± ± ± ±0.13 Comined ± ± ± ±0.06 Mens wi different supersript in e sme olumn differs signifintly (P<0.05) Egg Wid: Men egg wid for e omined ges in is study is 42.45±0.03mm (Tle 2). The 95% lower onfidene limits of egg leng re 42.39mm, 40.79mm, 42.42mm, 42.62mm, 43.01mm nd 42.80mm for e omined, group A, group B, group C, group D nd group E respetively. While e 95% upper onfidene limits re respetively 42.51mm, 41.03mm, 42.63mm, 42.91mm, 43.31mm nd 43.01mm. Shpe Index: The men shpe index for e omined ges in is study is 75.53±0.06% (Tle 2). The 95% lower onfidene limits of egg leng re 75.41%, 75.78%, 75.55%, 75.32%, 75.16% nd 74.55% for e omined, group A, group B, group C, group D nd group E respetively. While e 95% upper onfidene limits re respetively 75.65%, 76.26%, 76.03%, 75.84%, 75.78% nd 75.07%. Reltionship mongst orreltes studied: Correltion mongst e four vriles studied, re presented in Tle 3. Egg weight hd high positive orreltion wi egg leng nd egg wid nd very low negtive orreltion wi shpe index. This implies t reltionship etween egg wid nd egg weight is stronger n ssoition etween egg leng nd egg weight. Disussion Egg Weight: Age group A reorded e lest men egg weight while Age group D hd e mximum men egg weight. There ws onsistent inrese in egg weight wi inresing ge of hen efore it peked t ge group D, erefter ere ws deline in e egg weight t ge group E. Wi e exeption of ge group A t ws sttistilly different from e oer four ge groups, ere ws no sttistil differene (p>0.05) in e men egg weight of ge groups B nd C nd similrly, ere ws no signifint differene (p>0.05) in e men egg weight of ge groups D nd E (Tle 2). Wi dvning ge, men egg weight onsistently rise from ge group A to ge group D nd en delines fterwrds. This oservtion is in greement wi e works of O Sullivn et l. (1991); Bermudez et l. (1992); Gous et l. (2000); Peeles et l. (2000); Silversides nd Sott (2001). The men egg weight of 49.94g for Age group A (22-32 weeks) otined in is study is in onsonne wi e men egg weight of 49.80g otined y Choprkrn et l. (1998) who worked on Thi indigenous hens ged weeks. The men egg weight of 56.35g reorded for e ge group B is lose to 55.95g men egg weight reported y Monir et l. (2003) who worked on Rhode Islnd Red of similr ge in Bngldesh, nd lso e 56.72g otined y Bunhsk et l. (2005) who worked on Bok B-308 lying hen in Thilnd. However, Monir et l. (2003) who lso worked on White Leghorn reported men egg weight of 58.38g whih ws 2.39 perent higher n e men egg weight oserved for is ge group in e Hro lk strin in is study. This vrition my e ttriuted to e different reeds of lying hen, different nutrition pln nd e totl numer of e popultion smpled (Choprkrn et l., 1998). Egg Leng: There ws onsistent inrese in egg leng ross e ges from group A to group E. The highest men egg leng ws reorded in ge group E, while e lest egg leng ws reorded in ge group A. The onsistent inrese in men egg leng wi ge of lying hen oserved in is study grees wi reports of Anderson et l. (2004) nd Gunlu et l. (2003). The men egg leng of ge group E is 6.21% higher n t of ge group A. The men egg leng otined in is study is in oherene wi e 56.20mm otined y Monir et l. (2003) who worked on White Rok reed of lyers ut vrition of 2.90mm ws oserved y Monir et l. (2003) who lso studied White Leghorn reed, where he reported men egg leng of 59.10mm. This vrition ould e s result of e differenes in e reeds studied. Choprkrn et l. (1998) who rried out study on Thi indigenous pullets of similr ge s e ge group A, otined men egg leng of 54.00mm whih is lose to e vlue otined in is study. Egg wid: There is striking similrity in e distriution of egg weight nd egg leng suggesting n initil reltionship etween e two vriles. The egg wid stedily inreses from ge group A to group D efore it delines t ge group E, leit not sttistilly different (P>0.05). Egg wid inreses wi inresing ge of hen nd it peked t out yer old efore it delines. This my e due to e ft t, during e proess of egg formtion, s e ontent of e egg trvels down e ovidut it eomes ensed y e shell nd fored out 61

4 Aniknnd et l.: Sttistil modeling of egg mesurements Tle 3: Correltion oeffiient mtrix of vriles studied Egg Egg Egg Shpe weight leng wid Index Egg weight Egg leng Egg wid Shpe index Tle 4: Anlysis of vrine of ftors ffeting egg weight Soures df Men Squre Age group *** Egg Leng (L) *** Egg Wid (W) *** Shpe Index (S) * Egg Leng * Wid (LW) *** Error *** = P< 0.001, ** = P< 0.01; * = P <0.05 rough e vent. In pullets, e ovidut tends to e nrrower suh t only smll wid of shell n e fored long wi e egg ontent erey resulting in slimmer egg wid. Susequently, s e hen grows older, e ovidut eomes wider llowing lrger wid nd onsequently, e egg wid inreses wi ge. Derese t lter ges of e hen my e due to e deresed lium deposition for egg shell y e ging hen. The men egg wid otined in is study is similr to e 43.61mm otined y Anderson et l. (2004) who worked on e single om White Leghorn of similr ge nd lso lose to e 41.00mm otined y Choprkrn, et l. (1998) who worked on Thi indigenous hens. Shpe index: The onsistent derese in shpe index wi inresing hen ge (Tle 2) reveled t e shpe index of e eggs deresed wi ge euse shpe index is diretly proportionl to egg wid nd it is inversely relted to egg leng, whih implies t wi inresing ge, e rte t whih eggs eomes longer is fster n rte of eing wider. This oservtion is in greement wi e studies of Brnd, et l. (2004); Choprkrn et l. (1998) nd Gunlu et l. (2003). The omined men shpe index otined in is study is similr to e 75.60% reported y Hsn (2005) who worked on Fyoumi hens nd lso lose to e 75.08% oserved y Brnd et l. (2004) who worked on Is Wren Lyers. However, it is 1.43% higher n e men shpe index of 74.10% oserved y Monir et l. (2003) who worked on White Rok Lyers. Reltionship mongst orreltes studied: The reltionship etween egg leng nd egg wid ws modertely positive, while ere ws n inverse ssoition etween egg leng nd shpe index. The reson t my e dvned for is negtive reltionship is e ft t egg leng is e denominting ftor in estimting shpe index ording to Pnd (1996) nd Gunlu et l. (2003). This oservtion grees wi reports of Choprkrn et l. (1998). Egg wid shows positive orreltion wi shpe index leit low, is is euse shpe index in diretly relted to egg wid, nd is result is similrly oserved y Ozelik (2002); Kul nd Seker (2004). The reson for is ould e s result of e denser prt of e egg (yolk) oupying e wid re, whih trnsltes to hevier weight for e egg. This oservtion grees wi reports of Choprkrn et l. (1998); Frooq et l. (2001) nd Kul nd Seker (2004). Regression nlysis: The regression of egg leng, egg wid nd shpe index on egg weight ws highly signifint (P<0.01). This oservtion is in greement wi Choprkrn et l. (1998) who reported t egg weight ws positively regressed (P<0.01) to egg wid nd egg leng, however, he reported t regression of shpe index ws not signifint. The model desriing egg weight in is study is given s; where L, W nd S re respetively e Leng, Wid nd Shpe Index of e egg. Ftors ffeting egg weight: This nlysis of vrine (ANOVA) entils e inlusion of ge group s fixed ftor nd e orreltes studied s ovrites on egg weight. Wi e exeption of Shpe Index whih ws signifint t 5%, ll oer ftors studied were highly signifint (P<0.001). Egg leng ws e lrgest soure of vrition in is study, followed y ge group nd egg wid (Tle 4). The signifint effets of ge group reveled in is study hve een extensively reported y severl reserhers who hd worked on different reeds of hiken (Coutts nd Wilson, 1990; Monir et l., 2003 nd Gerer, 2006). The most signifint ftor ffeting egg weight in is study is egg leng (P<0.001) nd e sttistil differene in e mens is s presented in Tle 2. This oservtion onfirms e reports of Monir et l. (2003) nd Anderson et l. (2004). The signifint effet of egg wid is s refleted in e men seprtion ross e vrious ge groups (Tle 2), nd is my e due to e ft t e denser prt of e egg is loted round e wide re of e egg, erey positively ontriuting to e totl weight of e egg. This orroortes e initil oservtion of e regression of egg wid on egg weight. Though signifint, shpe index hd e lest effet nd is e lest ontriutor to e soures of vrition studied. This my e euse shpe index is funtion of egg leng nd egg wid rer n egg weight. Expetedly, e intertion of egg leng nd egg wid exerted highly signifint effet on e weight of e eggs. This is euse o ftors determine e volume nd holding pity of e egg nd onsequently e weight of e egg. Conlusion: Bsed on e results otined in is study, e following onlusions n e drwn on e reltionship etween egg dimensions nd egg weight; 62

5 Aniknnd et l.: Sttistil modeling of egg mesurements As e ge of e lying hen inreses, egg weight, egg leng nd egg wid inrese, while shpe index dereses wi ge of lying hen. Egg leng nd egg wid hd high positive orreltion wi egg weight, nd in e regression nlysis, egg leng nd egg wid hd high signifine on egg weight (P<0.001) ut shpe index ws only signifint t 5 perent. Age group, egg leng, egg wid, egg leng x egg wid intertion were highly signifint on egg weight (P<0.001) while shpe index exhiited signifine t 5 perent on egg weight. Aknowledgement The uors sinerely ppreite e ssistne of mngement nd stff of Iukun Frms Limited, Lgos, Nigeri, for supplying e eggs nd grnting us ess to eir filities. Referenes Anderson, K.E., J.B. Thrnington, P.A. Curtis nd F.T. Jones, Shell hrteristis of eggs from histori strins of single om white leghorn Chiken nd e reltionship of egg shpe of shell streng. Int. J. Poult. Si., 3: Bermudez, J.J., M. Prez nd J. Gonzlez, Effet of ody weight on egg weight in White Leghorn hens. Revist Cn de ieni Aviol, 19: Brnd, H.V.D., H.K. Prmeter nd B. Kemp, Effets of housing system out door vs ges nd ge of lying hens on egg hrteristis. Br. Poult. Si., 45: Bunhsk, C., K. Poosuwn, R. Nukrwe, K. Mrkvihitr, nd A. Chwesm, Effet of dietry protein on egg prodution nd immunity response of lying hens during pek prodution period. Int. J. Poult. Si., 4: Choprkrn, K., I. Slngm nd K. Jnk, Lying performne, egg hrteristis nd egg omposition in Thi indigenous hens. Coutts, J.A. nd G. Wilson, Egg Qulity Hndook. Queenslnd Deprtment of Primry Industries Informtion Series. Q Dnilov, R.V., Effet of hens ge on qulity of hing eggs nd emryoni development proeeding of 21st World s Poultry Congress 2000, Montrel, Cnd. Frooq, K.A.M., F.R. Durrni, K. Srilnd nd N. Chud, Prediting egg weight, shell weight, shell ikness nd hing hik weight of Jpnese quils using vrious egg trits s regressors. Int. J. Poult. Si., 2: Frooq, M., M.A Min, M. Ali, F.R. Durrni, A. Asqur nd A.K. Muqrr, Egg trits of Fyomi ird under sutropil onditions. Srd J. Agri., 17: Gerer, N., Ftors ffeting egg quslity in e ommeril lying hen: review. egg produers Federtions of New Zelnd (In)/Poultry industry Assoition of New Zelnd 96D Crlton Gore Rod, New Mrket, 1023, Auklnd. Gous, R.M., G.D. Brdford, S.A. Thouston nd T.R. Morris, Effet of ge of relese from light or food restritions on ge of sexul mturity nd egg prodution of lying pullets. Br. Poult. Si., 41: Gunlu, A., K. Kiriki, O. Cetin nd M. Crip, Some externl nd internl qulity hrteristis of ptridge (A. gre) eggs. Food Agri. Environ., 1: Hsn, M.R., Effet of feeding system on e egg prodution of Fyoumi hens of model reeding unit under PLDP progrmme in Bngldesh. Kimer, H., The Golden Egg University of Survey Guildford, Englnd. Kul, S. nd I. Seker, Phenotypi orreltion etween some externl nd internl egg qulity trits in e Jpnese quil (oturnix oturnix jponi). Monir, K.N., M. Slhuddin nd G. Mih, Effet of reed nd holding period on egg qulity hrtis of hiken. Int. J. Poult. Si., 2: O Sullivn, N.P., E.A. Dunnington nd P.B. Siegl, Reltionship mong ge of dm, egg omponents, emryo lipid trnsfer, nd hility of roiler reeder eggs. Poult. Si., 70: Ojo, S.O., Produtivity nd tehnil effiieny of poultry egg prodution in Nigeri. Int. J. Poult. Si., 2: Okeke, C.E., Rising helier poultry: Nigeri Ntionl Centre for Energy Reserh nd Development, University of Nigeri, Nsukk. Ozelik, M., The phenotypi orreltion mong some externl nd internl qulity hrteristis in Jpnese quil eggs. Vet. J. Ankr Univ., 49: Pnd, P.C., Shpe nd texture. In Textook on egg nd poultry tehnology, pp:57. Pndey, N.K., C.M. Mhptr, S.S. Verm nd D.C. Johri, Effet of strin on physil egg qulity hrteristis in white Leghorn Chikens. Indigenous J. Poult. Si., 21: Peeles, E.O., C.D. Zumwlt, S.M. Doyle, P.D. Gerrd, Ltour, M.A. Mtour, C.R. Byle nd T.W. Smi, Effet of reeder ge nd dietry ft soure nd level on roiler hing egg hrteristis. Poult. Si., 79: Silversides, F.G. nd T.A. Sott, Effets of Storge nd lying ge on qulity of eggs from two lines of hens. Poult. Si., 80: S-Plus, S-Plus 6.0 Professionl Relese 2. Insightful Corportion Westlke Avenue Nor, Suite 500, Settle, WA 98109, USA. Wilson, H.R. nd M.E. Surez, The use of egg weight nd hik weight oeffiient of vrition s qulity inditors in hery mngement. J. Appl. Poult. Res., 2: