Shell Thickness of Turkey Eggs Affects Cardiac Physiology and Embryo Survival 1

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1 Interntionl Journl of Poultry Science 5 (8): , 2006 ISSN Asin Network for Scientific Informtion, 2006 Shell Thickness of Turkey Eggs Affects Crdic Physiology nd Emryo Survivl V.L. Christensen, L.G. Bgley, T. Olson, J.L. Grimes, R.D. Rowlnd nd D.T. Ort 2 Deprtment of Poultry Science, College of Agriculture nd Life Sciences, North Crolin Stte University, Rleigh, North Crolin , USA Moroni Turkey Htchery, Moroni, UT Chelted Minerls Corportion, 0 West 900 South, Slt Lke City, Uth 8404, USA 4 Astrct: Supplementing 500 ppm of chelted clcium proteinte (CCP) to commercil reeder diet resulted in thicker shells nd improved emryo livility. The CCP diet ws fed to one hlf of flock of reeders on commercil frm tht ws suffering shell prolems, nd stndrd commercil diet ws fed to the remining hlf. Egg production, eggshell thickness, fertility nd htchility of eggs were ll monitored over n 8 wk lying period. Feeding CCP incresed shell thickness nd reduced numers of cull eggs fter 8 wk of ly compred to the controls. When differences in eggshell thickness were seen fter 0 weeks of egg production, emryo survivl nd crdic physiology were exmined in three trils compring the thicker shells to thin. Thick shells ( versus 0.9 mm) improved emryo survivl 2% y decresing numers of emryos dying lte in development compred to controls nd ffected crdic physiology. Thus, thick shells my improve emryo viility y ffecting crdic helth during the plteu stge in oxygen consumption. Key words: Shell thickness, emryo survivl, crdic physiology Introduction Prior reserch (Grimes et l., 2004) indicted tht feeding chelted clcium proteinte supplement (CCP) to turkey reeder hen diets improved emryo survivl in ging turkey reeder hens. The reson given ws tht shell qulity my hve een improved lte in the lying period, ut it is not known how shell thickness ffects emryo survivl. In susequent studies (Christensen et l., 200; Christensen et l., 2005), the functionl property of the shell, emryo crdic physiology nd poult growth nd qulity for d posthtching were ll improved following the ddition of CCP to the mternl diet. Eggshell conductnce incresed with mternlly fed CCP ccompnied y lrger neonte herts nd reduced hert rtes (Christensen et l., 2005). The myocrdi of emryos displyed lower concentrtions of lctte indicting less myocrdil ftigue during pipping of the shell nd htching. Other studies hve shown tht elevted crdic glycogen s well s incresed CK ctivity is typicl of crdiomyopthy in poults (Czrnecki, 99). The ojective of the current study ws to determine the effect of thicker shells on emryo crdic physiology, survivl, nd poult qulity in commercil setting. Mterils nd Methods A flock of 20,000 Lrge White hens of the Orlopp strin ws kept on commercil reeder frm. Hlf of the flock ws ssigned rndomly to e fed diet supplemented with.% clcite nd 0.05% Clkey (Chelted Minerls Corportion, Slt Lke City, UT) (CCP). The remining reeders were fed the stndrd diet of the compny contining.6% clcite. All diets were ville d liitum eginning t photostimultion (29 wk of ge). The period of egg lying for the study egn in My nd terminted in Septemer; therefore, eggs were produced in hot wether so egg production rtes were depressed nd shells were thinner. Becuse of requirements for the htchery, eggs for reserch were ville for only 8 weeks. Egg production nd shell thicknesses were recorded on weekly sis for 8 wk. Becuse no repliction of dietry tretments ws possile, no sttisticl nlysis ws performed on egg production dt nd no inferences cn e mde out the diets. Eggshell thickness ws mesured for,096 eggs during initil 4 wk of the study. Approximtely 50 eggs were selected rndomly weekly from ech tretment, roken open, the lumen ws rinsed wy with wter nd the shell with memrne intct ws ir dried. A piston micrometer (Ames, Amherst, MA) ws used to mesure the thickness t 4 points t the equtor of ech egg. Individul shells were the experimentl unit. Following determintion tht irds fed CCP produced thicker shells. Emryo physiology nd survivl in eggs of thick (THCK) nd thin (THIN) shells ws tested t weeks 0, 4 nd 8 of egg production. Approximtely 5,000 eggs from ech shell thickness group were set t the sme time in commercil htchery. Twenty eggs from ech group were selected within ech setting to verify eggshell thicknesses. In ll three settings, eggs from the CCP fed house showed thicker shells (0 wk, THCK = mm; THIN = 0.4mm; 4 wk THCK = mm, THIN = 0.7 mm; 8 wk, THCK = 0.4 mm; THIN =

2 Christensen et l.: Emryonic Hert mm). Within ech tril, eggs of oth thicknesses were set rndomly distriuted in the sme cinets nd incuted under the norml temperture nd humidity profiles used y the htchery. Oxygen ws supplemented to the incutors t rte of liters per min ecuse the eggs were incuted t high ltitude (c. 000 m). All eggs were trnsferred t d 25 of development to the sme cinet for htching. At the time of trnsfer, 6 eggs were plced rndomly into ech of the htching trys, nd the emryo survivl on ech try ws mesured. Trys (9/thickness/tril) served s the experimentl unit for the emryo survivl nlysis. The numer of poults htching on ech try ws counted nd the remining eggs were roken nd the contents visulized determining true fertility or emryo deth dt. The percentge of fertilized eggs tht htched on ech try ws used in the nlysis. Within ech tril, the time poults htched ws noted y oserving the numer of poults freed from the shell in ech of the replicte trys (one rck) from ech flock eginning t 60 h of development nd t 6 h intervls therefter. The percentge of the totl poults htched on ech try t ech time ws used in the nlysis. Times for emryos to ttin stge of development were lso recorded t the sme times on 25 rndomly selected eggs from ech flock using cndling light. The hours of incution required for ech emryo to ttin stge were used in the nlysis. Emryos were smpled for tissues eginning t dy 27 of development s descried in our prior experiment (Christensen et l., 2005). Individul emryos or poults were the experimentl unit. Poult qulity ws ssessed y mrking htchlings of ech of the htches from two incutor rcks (reeder eggs collected t 0, 4 nd 8 wk of production) with pint nd plcing them rndomly into rooder houses within the compny system. Poult mortlity for pproximtely,200 toms nd,200 hens ws recorded for 7 dys following plcement in ech of the three independent trils. Mortlities were utopsied to determine cuse of deth. Ech htch ws the experimentl unit for the sttisticl nlysis. Hert rtes were mesured using n oscilloscope (Avitronics, UK) s descried previously (Christensen et l., 2005). At externl pipping nd htching, five emryos or five htched poults were selected rndomly from trys within ech tretment nd were weighed with nd without the yolk nd smpled for lood, hert nd liver tissues. Blood plsm ws nlyzed for CK nd LDH ctivities s well s for glucose nd lctte concentrtions. Crdic nd heptic tissues were ssyed for glycogen nd lctte concentrtions. All procedures were descried previously (Christensen et l., 2005). Individul emryos or poults were the Tle : Eggshell thickness (mm) of turkey eggs from dms fed two sources of clcium Diet Weeks of ly CCP CON c 0.4 c c c 0.4 c c c c 0.4 c c 0.9 c d 0.7 Men 0.4 Men±SEM ±0.0 Proilities Diet Week N = 096 Diet x Week CCP=fed 0.05% chelted clcium proteinte plus.4% clcite s clcium source; CON= fed.6% clcite s clcium source.,,c Mens with different superscript differ significntly (P< 0.05). experimentl unit for this nlysis. Dt were nlyzed using the generl liner models procedure of SAS (998). Eggshell thickness tretments were determined y compring 50 eggs from ech house ech wk of egg production. All remining dt were grouped into two eggshell thicknesses (THCK nd THIN) y three ges (Weeks 0, 4 nd 8 of egg production) fctoril for nlysis. Age of reeder flock ws considered fixed fctor in the nlysis. Mens differing significntly were seprted with the lest squre mens. Proility ws sed on P < 0.05 unless otherwise noted. Results th After the 0 wk of production, greter differences in thicknesses were pprent with eggs collected from the group fed CCP hving thicker eggshells thn did the controls (Tle ). The group fed CCP produced fewer cull eggs thn the controls ut showed not differences in egg production rtes (dt not shown). THCK shells incresed the percentge of emryos surviving compred to the THIN shells (Tle 2). Fewer emryos died t wk 4 of development in the THCK shells thn in THIN shells. An eggshell thickness y tril interction ws noted for externlly pipped eggs (dy 27 of development). The percentge of pipping emryos dying ws greter in the THIN thn THCK shells in trils t weeks 0 nd 8 of egg production ut no differences were seen t week 4. THCK prolonged development time of emryos compred to THIN (Tle ). In ech tril, emryos in 797

3 Christensen et l.: Emryonic Hert Tle 2: Emryo survivl nd times of development t which mortlity occurred for eggs produced y turkey reeder hens of two thicknesses Shell Tril Emryo Mortlity Mortlity t Mortlity t survivl t week week 4 (%) pipping (%) (%) (%) Thin c Men Thick c Men Men±SEM 9.2 ± ± ± ± 0. Proilities Shell NS Tril NS NS NS Shell x Tril NS NS NS Thick=shells were mesured to e mm. Thin=shells were mesured to e 0.9 mm.,,c Mens with different superscript differ significntly (P< 0.05). Tle : Time of htching (% of totl htched) for turkey eggs of two thicknesses Hours of incution Shell Thick Thin Men±SEM.2 ± ± ± ±.2 Proility Shell Tril Shell x Tril NS NS NS NS Thick=shells were mesured to e mm. Thin=shells were mesured to e 0.9 mm., Mens with different superscript differ significntly (P< 0.05). Tle 4: Time for emryos to ttin stge of development nd remin t stge when developing in turkey eggs of two thicknesses Stge of development Internl pipping Externl pipping Htched Shell Time D time Time D time Time Thick Thin Men±SEM 62 ± 4.9 ±. 627 ± 9.8 ± ± Proility Shell NS NS NS Tril NS NS NS Shell x Tril NS NS NS NS NS Thick=shells were mesured to e mm. Thin=shells were mesured to e 0.9 mm. D time = the mount of time tht the emryo remined t tht stge efore dvncing to the next., Mens with different superscript differ significntly (P< 0.05). THCK hd longer developmentl times thn did Emryo nd neonte liver weights did not differ etween emryos from the THIN. Tle 4 indictes tht the longer the dietry tretments (dt not shown). Poults from development time ws due primrily to n extended time eggs with THCK did not disply etter poult livility thn required for emryos in THCK eggs to pip internlly thn THIN in rooder houses (Tle 7). for THIN. Tle 8 shows tht hert rtes for 25 d emryos from Htchlings from THCK were pproximtely 2 g hevier THCK nd those of the THIN did not differ, ut t 26 d, without the yolk thn their counterprts from THIN (Tle emryo hert rtes from the THIN were greter thn 5), nd poults from THCK lso displyed less residul those from the THCK. yolk tht did those from THIN. Herts in 27-d old Emryos from the THCK hd elevted crdic glycogen emryos from THCK weighed more thn those from concentrtions t d 27 ut depressed levels t d 28 of THIN on oth reltive nd solute ses (Tle 6). development compred to THIN (Tle 9). No significnt 798

4 Christensen et l.: Emryonic Hert Tle 5: Body nd yolk weights (g) of emryos nd poults from Tle 6: Hert weights of emryos nd poults from eggs of two turkey eggs of two thicknesses thicknesses Dy of development Dy of development Shell Tril Shell Tril Without yolk Asolute (mg) Thin Thin Thick Thick Men±SEM 49.6± ±0.4 Men±SEM 27±4 08±6 Proilities Shell NS 0.0 Proilities Shell 0.0 NS Tril 0.04 NS Tril 0.02 NS Shell x Tril NS NS Shell x Tril NS NS Yolk Reltive (%) Thin Thick Thick Thin Men±SEM 4.0± ±0.2 Men±SEM 0.55± ±0.0 Proilities Shell NS 0.02 Proilities Shell 0.0 NS Tril NS NS Tril 0.0 NS Shell x Tril NS NS Shell x Tril NS NS Thick=shells were mesured to e mm. Thin=shells were Thick=shells were mesured to e mm. Thin=shells were mesured to e 0.9 mm. mesured to e 0.9 mm., Mens with different superscript differ significntly (P< 0.05).,Mens with different superscript differ significntly (P< 0.05). differences were seen in crdic lctte concentrtions. exmined suffered shell qulity prolems ecuse of Htchlings (28-d) from the THCK hd depressed heptic hot wether. In support of prior dt (Grimes et l., 2004; glycogen concentrtions compred to THIN (Tle 0), Christensen et l., 2005), dding CCP to the commercil nd pipping emryos (27-d) from THCK displyed diet incresed shell thickness in hlf of the ges elevted heptic lctte concentrtions compred to exmined with the difference in eggshell thickness THIN. When the totl mounts of glycogen nd lctte in eing greter s the hens ged. In the emryo survivl the liver reltive to one nother were exmined, no experiments, pproximtely 2% more emryos from differences were seen t pipping, however, the htched THCK survived development in the current study thn did poults hd more heptic lctte thn glycogen indicting those from THIN. Most of the difference in survivl ws crdiomyopthy. in emryos from THCK shells tht survived during 25 to Activity of CK ws elevted in poults from THIN 28 d of development compred to THIN. Thus, THCK compred to THCK t htching indicting greter tissue improved emryo livility t the end of development. In oxygen det nd crdiomyopthy in those poults (Tle contrst to prior study (Grimes et l., 2004), the ). No differences were noted in the ctivities of LDH t improvement in emryo survivl ws independent of the ny time of development. ge of the reeder hen. A mjor difference etween the THCK depressed plsm glucose concentrtions in current nd prior studies (Grimes et l., 2004; htching poults ut not in pipping emryos compred to Christensen et l., 2005) ws the presence of thin shells those in THIN (Tle 2). No differences were noted in in flocks prior to feeding CCP to reeders in the current the concentrtions of plsm lctte t either stge of study. Most flocks within the compny t the time of the development exmined. experiment were producing eggs with thin shells. Prior studies suggested tht shell thickness my lso ffect Discussion Incresed shell thickness improved emryo survivl under field conditions in the current study t eggshell conductnce (Christensen et l., 2005). We were unle to mesure eggshell conductnce in the current study ecuse of precluding fctors in the commercil turkey reeding compny. The flock commercil htchery opertion, ut peripherl dt (i.e. 799

5 Christensen et l.: Emryonic Hert Tle 7: Mortlity (%) t 7dys post htching of htchlings from Tle 9: Crdic glycogen nd lctte (mg/g of wet tissue mss) eggs of two thicknesses in emryos nd poults from eggs of two thicknesses Shell Tril Tom Hen Dy of development mortlity mortlity (%) (%) Shell Tril Thick.76.4 Glycogen Thin Men Thin Men Thick Men Men±SEM.44±0.0 Men Proilities Shell NS NS Men±SEM.± ±0.06 Tril NS NS Proilities Shell Shell x Tril NS NS Tril Thick=shells were mesured to e mm. Thin=shells were Shell x Tril NS NS Lctte Thin Thick Men±SEM.9± ±0.09 Proilities Shell NS NS Tril NS NS Shell x Tril NS NS Rtio (Totl glycogen to totl lctte) Thin mesured to e 0.9 mm., Mens with different superscript differ significntly (P< 0.05). Tle 8: Hert rtes (pm) of emryos nd poults from turkey eggs of two thicknesses Dy of development Shell Tril Thin Men Thick Men±SEM 225±2 226±2 Proilities Shell NS Tril NS Shell x Tril NS NS Tril mens Tril Hert rte Thick=shells were mesured to e mm. Thin=shells were mesured to e 0.9 mm., Mens with different superscript differ significntly (P< 0.05) Thick Men±SEM 0.70± ±0.02 Proilities Shell Tril Shell x Tril NS NS Thick=shells were mesured to e mm. Thin=shells were mesured to e 0.9 mm., Mens with different superscript differ significntly (P< 0.05). delyed htching times nd incresed shell thickness) suggest tht the functionl property of the eggshell my hve een ffected y shell thickness s well. It ws concluded from the current study tht incresed shell thickness resulted in longer emryo developmentl periods nd improved survivl rtes when compred to eggs with thin shells. In greement with prior studies (Christensen et l., 2005), THCK in the current study ffected emryo crdic physiology. In the prior study, herts grew fster the initil d of life when the poult htched from thicker shelled-egg. It is speculted tht the ltertions my hve een medited through the shell nd eggshell conductnce of the vitl gses of oxygen nd cron dioxide nd conductnce constnts tht prolonged the emryo developmentl period (Christensen et l., 200). THCK decresed hert rtes on d 26 of development nd incresed hert weights on dy 27 of development. No differences in hert weights were seen t htching, however, the myocrdium showed residul effects of elevted glycogen nd plsm CK s seen in poults suffering crdiomyopthy (Czrnecki, 99). The myocrdium exhiited incresed glycogen prior to htching ut the reverse ws true following htching. Thus, mortlity seen in emryos t 25, 26 nd 27 d of development my reflect filed compenstions in crdic physiology mde y emryos to different eggshell conductnce when they were incuted in n oxygen enriched environment t high ltitude. As soon s the shell ws roken t pipping nd the emryo or poult djusted its respirtion rte s opposed to relying upon the shell, hert weights recovered quickly 800

6 Christensen et l.: Emryonic Hert Tle 0: Heptic glycogen nd lctte (mg/g of wet tissue mss) in emryos nd poults from eggs of two thicknesses Dy of development Shell Tril Glycogen Thin Men.09 Thick Men.2 Men±SEM.9± ±0.07 Proilities Shell 0.05 NS Tril NS NS Shell x Tril NS NS Lctte Thin Thick Men±SEM.06±0.04.5±0.04 Proilities Shell 0.02 NS Tril NS NS Shell x Tril NS NS Rtio (Totl glycogen to totl lctte) Thin Thick Men±SEM.09±0. 0.9±0. Proilities Shell NS 0.05 Tril NS NS Shell x Tril NS NS Thick=shells were mesured to e mm. Thin=shells were mesured to e 0.9 mm., Mens with different superscript differ significntly (P< 0.05). nd were not ffected y shell thickness t htching. Survivl of htchlings following plcement in rooders in our current study ws identicl for THCK nd THIN poults in ll three trils. Enhnced growth of poults to - d post-htching from eggs treted similrly hs een reported previously (Christensen et l., 2005). We were unle to weigh the poults t d post-htching s hd een reported previously (Christensen et l., 2005) to ssess poult qulity. Spontneous crdiomyopthy (turkey roundhert disese) is redily oserved in the commercil compny locted t high ltitude. Autopsy of the poults tht died in the current study showed no consistent trends in the incidence of spontneous crdiomyopthy proly ecuse so few poults died (< 5 in some tretments) in the current study. Lrger numers of poults need to e plced to ssess correctly the incidence of spontneous crdiomyopthy. Erlier studies in crdiomyopthy poults (Czrnecki et l., 975) noted excessive glycogen in vrious tissues, specificlly in left nd right ventriculr tissue; with the right ventricle hving greter increse in glycogen content (Czrnecki nd Evnson, 980). Avin myocrdium hs no ility to recycle lctte vi the Cori cycle so it is dependent upon the liver for tht function. In crdiomyopthic poults, glycogen grnules were oserved in heptic lysosomes (Stley et l., 978) which were hypothesized to result from lock in the citric cid cycle preventing the complete rekdown of glycogen nd resulting in ltered heptic metolism, including decresed protein synthesis nd incresed metolism of ft, possily ssocited with liver dmge. It ws determined tht glycogen rnching levels were unltered; therefore, the est explntion for the ltered levels ws chnge in degrdtion of glycogen (Czrnecki nd Evnson, 980; Czrnecki et l., 978; Mirslimi et l., 990). Elevted lctte nd incresed glycogen concentrtions were seen in poults htching from THIN in the current study nd poults htching from THIN exhiited incresed mounts of lctte reltive to glycogen (Rtio) in heptic tissue indicted the slower recycling reported in crdiomyopthy previously (Stley et l., 978). Lctte concentrtions in the myocrdium of pipping emryos were not ffected y thicknesses, ut the rtio of totl glycogen to totl lctte ws. THIN depressed the mount of glycogen reltive to lctte in hert tissue in poults, nd THIN lso cused elevted plsm CK ctivity in poults. Elevted CK ctivities s well s reduced glycogen to lctte rtios in liver indicte crdiomyopthy (Czrnecki, 99; Czrnecki nd Evnson, 980) suggesting tht poults htching from THIN my hve een in oxygen det. Thus, reduced shell thickness my ffect myocrdil energy metolism nd myocrdium ftigue my e fctors in the oserved reduced hert weight nd emryonic mortlity. Thus, oservtions from the current study my support the ide tht thick shells improved emryo survivl vi djustments in crdic physiology, ut shell thickness hd no effect on the survivl of the htchling despite displying elevted CK nd ltered totl glycogen to lctte rtios t htching. The resons tht THIN my hve resulted in crdic prolems re unknown. Previous reserch indicted no reltionship etween egg specific grvity, n estimte of shell thickness, nd crdiomyopthy in turkeys (Gdzinski et l., 99). In our study, chnges in crdic physiology were redily oserved, nd my hve een relted to eggshell conductnce nd eggshell conductnce constnts insted of just shell thickness 80

7 Christensen et l.: Emryonic Hert Tle : Blood plsm cretine kinse (CK) nd lctte Tle 2: Blood plsm glucose nd lctte concentrtions dehydrogense (LDH) ctivities (U/L) of emryos nd poults from eggs of two thicknesses (mg/dl) in emryos nd poults from eggs of two thicknesses Dy of developmentshell Dy of development Shell Tril CK Thin,7 2,840 2,47 2,206,98 2,08 2,87 Thick,782 2,4 2,449 2,08,45 2,248 2,66 Men±SEM,468±9 2,277±66 Proilities Shell NS 0.05 Tril NS NS ShellxTril NS NS LDH Thin Thick Men±SEM 4±8 552±0 Proilities Shell NS NS Tril NS NS ShellxTril NS NS Thick=shells were mesured to e mm. Thin=shells were mesured to e 0.9 mm., Mens with different superscript differ significntly (P< 0.05). (Christensen et l., 2005). The conductnce property of n egg differs from specific grvity ecuse it is functionl. It ensures three requirements re met in timely mnner for successful htching (Rhn, 98). One of the requirements is tht the totl mount of oxygen tht will hve een consumed is out 00 ml/g of egg weight. Poults from thin-shelled eggs htched erlier thn those from thick-shelled eggs suggesting tht the emryos my not hve hd sufficient time to consume 00 ml of oxygen per g prior to emerging from the shell (Rhn, 98; Christensen et l., 997; Christensen et l., 999). If emryos from thin-shelled eggs did not meet this requirement, then emryonic tissues must mke djustments for neroic metolism (Christensen et l., 999). One of the djustments mde y hypoxic turkey emryos is reduction in hert weight (Christensen et l., 999). Thus, oservtions of the current study my suggest tht ltered htching times due to thin shells is response to hypoxi tht ffects crdic tissue nd increses emryonic mortlity t 25, 26 nd 27 d of development. In conclusion, thicker shells resulted in 2% etter emryo livility t the commercil htchery nd cn improve the survivl of turkey emryos. This oservtion Tril Glucose Thin Thick Men±SEM 97± 22±2 Proilities Shell NS 0.02 Tril NS NS ShellxTril NS NS Lctte Thin Thick Men±SEM 4± 6± Proilities Shell NS NS Tril NS NS ShellxTril NS NS Thick=shells were mesured to e mm. Thin=shells were mesured to e 0.9 mm., Mens with different superscript differ significntly (P< 0.05). my e prticulrly useful for eggs produced in hot wether. Although thicker shells ffected emryo crdic physiology nd survivl, it did not ffect the survivl of the htchlings to 7 d of ge. References Christensen, V.L., W.E. Donldson nd K.E. Nestor, 997. Effects of n oxygen-enriched environment on the survivl of turkey emryos etween twenty-five nd twenty-eight dys of ge. Poult. Sci., 76: Christensen, V.L., W.E. Donldson nd K.E. Nestor, 999. Effect of supplementl oxygen on lood plsm orgnic cids within emryos from selected lines of turkeys. Poult. Sci., 78: Christensen, V.L., W.E. Donldson nd K.E. Nestor, 999. Length of the plteu nd pipping stges of incution ffects the physiology nd survivl of turkeys. Br. Poult. Sci., 40: Christensen, V.L., D.T. Ort nd J.L. Grimes, 200 Reltionship of eggshell conductnce to neontl crdic physiology. Int. J. Poult. Sci., 2: Christensen, V.L., L.G. Bgley, J.L. Grimes, R.D. Rowlnd nd D.T. Ort, Effect of chelted clcium proteinte fed in the mternl diet of turkey reeders on emryo crdic physiology nd survivl. Int. J. of Poult. Sci., 5:

8 Christensen et l.: Emryonic Hert Czrnecki, C.M., K. Renu nd E.F. Jnkus, 975. Blood glucose nd tissue glycogen levels in turkey poults nd spontneous round hert disese nd furzolidone-induced crdiomyopthy. Avin Dis., 9: Czrnecki, C.M., A. Jegers nd E.F. Jnkus, 978. Chrcteriztion of glycogen in selected tissues of turkey poults with spontneous round hert disese nd furzolidone-induced crdiomyopthy. Act Ant., 02: -9. Czrnecki, C.M. nd O.A. Evnson, 980. Distriution of myocrdil glycogen in turkey poults during development of furzolidone-induced crdiomyopthy. Poult. Sci., 59: Czrnecki, C.M., 99. Influence of exogenous T 4 on ody weight, feed consumption, T 4 levels nd myocrdil glycogen in furzolidone-fed turkey poults. Avin Dis., 5: Gdzinski, P., T. Reidy, J.P. Villncourt nd R.J. Julin 99. The reltion of egg specific grvity to the incidence of spontneous crdiomyopthy in tom turkeys. Avin Dis., 7: Grimes, J.L., S. Noll, J. Brnnon, J.L. Godwin, J.C. Smith nd R.D Rowlnd, Effect of chelted clcium proteinte dietry supplement on the reproductive performnce of Lrge White Turkey Breeder Hens. J. Appl. Poult. Res., : Mirslimi, S.M., F.S. Qureshi, R.J. Julin nd P.J. O Brien 990. Myocrdil iochemicl chnges in furzolidone induced crdiomyopthy in turkeys. J. Comp. Pth., 02: Rhn, H., 98. Gs exchnge in vin eggs with specil reference to turkey eggs. Poult. Sci., 60: SAS Institute, 998. A User s Guide to SAS 98. Sprks Press, Inc., Cry, NC. Stley, N.A., G.R. Noren, C.M. Bndt nd H.L. Shrp 978. Furzolidone-induced crdiomyopthy in turkeys. J. Pth., 9: The mention of trde nmes in this puliction does not imply endorsement of the products mentioned nor criticism of similr products not mentioned. 80