Effect of ascorbic acid on embryonic development, hatch time and growth of extended delayed placement of broiler chickens

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1 Arch. Geflüelk. 1998, 6 (1), 11-, ISSN Verla Euen Ulmer GmbH & Co., Stuttart Effect of ascorbic acid on embryonic development, hatch time and rowth of extended delayed placement of broiler chickens Die Wirkun von Askorbinsäure auf die embryonale Entwicklun, Schlupfzeit und Wachstum von Broilerküken A. H. Zakaria, 1 A. A., AL-Latif and M. A. AL-Anezi Manuskript eineanen am. April 199 lntroduction The effect of ascorbic acid (AA) on poultry has been extensively reviewed by PARDUE and THAXTON (1986). Additional information can be taken from recent reports (see FLETCHER and CASON, 1991; TAKAHASHI et al., 1991; KuTLU and FoRBES, 1993; RoBERSON and EowARDs, 199; SATTERLEE et al., 199; McKEE and H ARRJSON, 1995; KRATZER et al., 1996; KEsHAVARZ, 1996). Althouh many studies have been conducted, the role of AA durin e incubation has yet to be determined. We therefore decided to investiate the effect of AA durin e incubation on embryonic development of broiler chickens. In a previous report (ZAKARIA and AL-ANEZ1, 1996) positive responses in hatchability, and body weiht of chicks at hatch to AA were suested. On the other hand, holdin chicks in an incubator for a proloned period of time followin hatch (rane of 1 to 8 h) reduced chick placement weiht (FANGUY et al., 1980; H AGER and BEANE, 1983; W YATT et al., 1985) and reduced body weihts at aes of 1 and 8 d (WYATT et al., 1986) and at 9 d (WYATT et al., 1985). Furthermore, H AGER and BEANE (1983) concluded that the relationship between holdin time and subsequent body weihts was more pronounced in one stock than in the other. Because body weiht is important for the industry, and AA biosynthesis durin the first day of hatch is limited (HoRNJG and FRIGG, 199), it is of economical interest to investiate the role of AA as an anti-stress aent. This study was conducted to determine the effect of AA on embryonic development, hatch time and body weiht of chickens when time of removal of chick from the hatcher was delayed. Materials and methods investiated the effect of levels of AA had on hatch time and on body weiht after extended delayed removal from the incubator. Es (385) were obtained from H ypro commercial broiler parent stock and placed into an incubator 1 D epartment of Anima! Science, Faculty of Ariculture, Damascus University, Damascus, Syria Department of Anima! Production, Faculty of Ariculture, Kin Saud University, Riyadh 11, P.0. Box 60, Kindo m of Saudi Arabia Archiv für Geflüel kunde 1/ 1998 (Maino, Italy) operated at 3.6 C and about 55 % relative humidity. Es were turned automatically once every hour. At d of incubation es were examined and those with livin embryos (61) were distributed at random to 3 roups: those injected with 0.1 ml of sterile saline solution containin either or m of AA per e and an uninjected control. Ascorbic acid solutions were freshly prepared and injected in the!are end of the e over the inner shell membrane. One hundred and 00 m of AA (Hoffmann La Roche, AG, CH-00, Basel, Switzerland) were weihed and transferred to ml sterile interior, nonadditive vacutainer tu bes and enclosed by aluminium foil. Detailed procedures of preparations of vitamin solutions and injection conditions were described previously (ZAKARIA and AL-ANEZI, 1996). The es were returned to the incubator and held there till 19 d of incubation where es of each treatment were transferred to separate hatchin compartments and placed in the same incubator with temperature and humidity control (3.5 C, % relative humidity. Hatchin time and posthatch treatments Hatchin time for each treatment was recorded by countin the number of chicks hatched at 6-h interval startin from 98 to 58 h of incubation. Additional recordin was clone at 55 h of incubation. All chicks sufficiently dry for removal at their respective hatch time were removed from the incubator, win-banded and weihed. H alf of chicks of each treatment were iven orally or m of AA dissolved in 0. ml sterile saline. The remainin chicks were iven 0. ml sterile saline solution. As a result 6 treatment roups were performed. The treatment roups were : 1) control durin incubation plus m AA after hatch; ) control durin incubation plus saline after hatch; 3) m AA durin incubation plus m after hatch; ) m AA durin incubation plus saline after hatch; 5) m AA durin incubation plus m after hatch, and 6) m AA durin incubation plus saline after hatch. Oral administration solution was withdrawn into a sterile 5-ml syrine (Kawamoto Bandae Material Co. Ltd., Osaka, Japan) and the needle was removed thereafter. The chick was held in the left hand, its mouth was opened, by the help of the anterior end of the syrine, and the solution was poured over the base of the tonue. The head of the chick was allowed to vibrate ently between forefiner and thumb of the left hand for a while so that no solution was thrown out of the mouth. Chicks were then transferred to another incubator

2 1 ZAKARIA et al., Effect of ascorbic acid on embryonic development, hatch time and rowth of extended delayed placement of broiler 8 bd 6 c ~ : -~ 0 bd bd 18 "O... " 0 16,.Q 1!; e '- 1 0 :E :.0 -= -= 8 ' 6 ~ Q --- control --- maa m AA Fi. 1. The effect of ascorbic acid injeccion at Day of incubation on hatch time of commercial broiler chickens () --- = Uninjected control -- = Es injected with m of AA at d of incubation -.t.- = Es injected with m of AA at d of incubation Die Wirkun von Ascorbinsäure-Injektionen am. Brutta auf Schlupfzeit der Verkaufsküken (Versuch 1) --- unbehandelte Kontrolle -- Eier mit m AA am. Brutta injeziert -.t.- Eier mit m AA am. Brutta injeziert h of incubation operated at 3.5 C and relative humidity of about 5% when they were held in wire compartments (one compartment for each treatment) for 18 to 8 h after hatch. They were then moved to uncontrolled environmental house. The chicks were floor reared on litter of lon wheat straw under fluctuatin room temperature ( to 33 C), relative humidity (0-%) and continuous liht. A commercial broiler ration was provided ad libitum throuh manual feeders. Water was provided ad libitum. Experiments -5 Four experiments (Experiments, 3, and 5) usin more than 110 settable es with livin embryos of commercial broiler parent stock (Hypro) were conducted to determine the effect of AA dippin durin incubation on embryonic weiht, hatchability, cull chicks, embryonic mortality and body weiht of normal hatched chicks. Experimental treatments Experiment was carried out at d of incubarion with the followin treatments: 1) es dipped in 3% solution of AA for 3 min. and ) control. Experiment 3 was conducted usin the same treatments used in Experiment except that Experiment 3 was carried out at 1 d of incubation. Experiment took place at 19 d of incubation and the treatments were as follows: 1) es dipped in 3% solution of AA for 1.5 min. and ) control. Experiment 5 took place usin the same treatments used in Experiment except that Experiment 5 was carried out at 11 d of incubation. Four,, 3 and 5 independent trials of each experiment were conducted at monthly intervals for a total of,, 3 and 5 replicates (incubation trays) for Experiments, 3, and 5, respectively. About 130 settable broiler es laid the same day were obtained from the same commercial farm for each trial of Experiments and 3 and 1 es for each of Experiment and 5 and roups of es were randomly selected and weihed to the nearest 0.1. The es (130 or 1) were placed at random into the same incubator (Maino, ltaly) for 1, 16, 18 and d of incubation for each trial of Experiments, 3,, and 5 respectively. Incubation conditions were as described in Expe- riment 1. Es were individually candled for determination of livin embryos at, 1, 19 and 11 d of incubation and only es with livin embryos were distributed at random on treatment roups ( 0 es each for Experiments and 3, and 30 es each for Experiments and 5) accordin to the experimental desin and individually coded. Preparation of vitamin solution 3% for e dippin was done shortly before the treatment. Seventy-five of AA (Lot 11601) were dissolved in.5 liter of the sterile saline solution (stored at C) usin clean lass jar (SCHOTT, DURAN 3000 ml, Germany) externally enclosed by aluminium foil. A sheet of sterile cloth auze was used to surround the anterior of another 5000 ml clean lass jar. The es (0 or 30 es) containin Lvin embryos were arraned in the jar; then the vitamin was poured into it. The es remained dipped in the solution for 3 min. (Experiments and 3) or 1.5 min. (Experiments and 5) and then removed from the jar as a mass by means of the auze and immediately dried by wrappin each e thorouhly with tissue paper. On the 19th d of incubation, es of each trial of each experiment were removed from the incubator and transferred to separate hatchin compartments and placed in the same incubator. The conditions of hatchin of Experiments, 3, and 5 were carried out as described in. Durin the process of e transfer to hatchin compartments, es were randomly selected from each roup of Experiments and 3 for body weiht testin to d after startin the treatment. The embryos were weihed individually after removin the yolk sac and wrapped thorouhly with tissue paper. Observations of the number of saleable chicks hatched, cull chicks, es with dead embryos and es with livin embryos and body weiht at hatch to the nearest 0.1 were made on each treatment at hatch. Statistical Analysis The experimental unit for hatchability at each h of incubation was the replicate of 88, 8, and 86 treatd es with livin embryos and transferred to hatchin compartment for an unin- Archiv fü r Geflüelkunde 1/ 1998

3 Z AKA RJ A et al., Effect of ascorbic acid on embryonic development, hatch time and rowth of extended delayed placement of broiler jected control, or m of AA, respectively. The number of sufficiently dry for removal chicks hatched at each hatch time of each treatment was expressed as a percentae of the treated es. The individual bird was used as the experimental unit for body weiht. The data on body weiht were subjected to one-way analysis of variance utilizin procedures of SAS (SAS Institute, 1989). Body weiht at, 1, and 9 d of ae were analyzed separately for males at each ae. Treatment means for males at each ae were compared by Duncan's multiple rane test with a 5% level of probability for those havin a sinificant F test. Body weiht at, 1, and 9 d of ae for females were analyzed in the same way. Experiments - 5 The data from 'Experiments, 3,, and 5 were analyzed by a t-test, usin TTEST procedures of SAS (SAS Institute, 1989), to compare control and AA treatment roups for embryo weiht, hatchability, cull chicks, unhatched es with livin embryos and unhatched es with dead embryos, embryo weiht and chick hatch weiht for each variable of each Experiment separately. Four,, 3 and 5 independent monthly trial were conducted within throuh 5, respectively and served as replicates over time. The replicate was used as the experimental unit for data analysis of hatchability, cull chicks, unhatched es with livin embryos and unhatched es with dead embryos. The individual values were used as the experimental unit for data analysis of embryo weiht and chick weiht at hatch. Percentaes were transferred to arc sine square roots prior to analysis and converted to the oriinal scale for presentation. Sinificam was claimed when P was less than 5 %. cause AA biosynthesis durin incubation (ZwANN and LAM, 199) is limited, treatment of AA at d of incubation miht have affected the activity of the thyroid land durin the hatchm process. Body weiht: The body weiht of the male and female birds at, 1 and 9 d of ae are presented in Tables 1 and. The results show statistical sex difference in the response of AA, particularly m durin incubation plus m after hatch, which resu!ted in reater (P < 0.05) body weihts of males; in females there was no sinificant difference. PARDUE et al. (1985) found that heatin male chicks at week of ae reduced plasma potassium, body weiht ain, relative bursa and spieen weihts and anti-sheep erythrocytes level, whereas heatin increased clocal temperature, plasma protein, corticosteroid levels, and mortality. However, pre-treatment of AA at 1-3 wk of ae alleviated many of these stress-related responses. Experiments - 5 Dippin es in 3% AA solution for 3 min. resu!ted in a sinificant decrease in embryo weiht and hatchability and a sinificant increase in embryonic death at and 1 d of incubation (Tab. 3). Ascorbic acid treatment for 1.5 min. at 19 d of incubation did not affect hatchability, cull chicks, and embryonic death and body weiht at hatch, but increased the unhatched es with livin embryos (table 3). Dippin es in 3% AA solution for 1.5 min. at 11 d of incubation yielded a Table 1. The effect of ascorbic acid on body weiht (mean S.E. ) of male broiler chickens () Die Wirkun v on Askorbinsäure auf das Körperewicht männlicher Kük en (Versuch J) Results and Discussion Treatment of AA m Du rin After incubation hatch Hatchin time: Hatchin time for each treatment of is iven in Fiure 1. As a trend, the results showed that chicks from AA treatments, particularly m AA, have hatched earlier than chicks from the control. There are no known reports of the effects of supplemental AA on hatchin time. The mechanism by which AA affects hatchin time remains obscure. One plausible mechanism for the early chick hatchin of AA treatments involves the adrenal land. Ascorbic acid injection at a dose of m per e durin the later staes of incubation may have a role in reducin stress because AA treatment led to the reduction of corticosterone (SATIERLEE et al., 199; KUTLU and FoRBES, 199; McKEE and H ARRISON, 1995) which is usually associated with stress, thus the AA treated embryos reserved the vitality and enery needed to emere from the shell earlier than the control. Another mechanism for the dissimilarity in hatchin time involves the thyroid land. Triiodothyronin (T3) appeared to be implicated in the pulmonary ventilation process of the avian embryo (KüHN et al., 1993). KOHN et al. (1993) reported data showed abrupt increase in T3 between d 19 and hatchin and connected the increase with internal pippin and the transformation from the allantoic to pulmonary respiration. Plasma ascorbic acid concentration peaked on day 1, then radually declined until day 18, before risin aain around the time of pippin and hatchin (W1LSON and ]AWORSKI, 199). BeArchi v fü r GeRü elk unde 1/ No. birds ae in days b 3ab 3'b d cd 5ab 51" 0b' 88 b Mcans within a column w ith no common supcrscript differ sinificantly (P < 0.05 ) Table. The effect of ascorbic acid on body weiht (mean S.E.) of female broiler chickens () Die Wirkun v on Askorbinsäure auf das Körperewicht weiblicher Küken (Versuch 1) Treatment of AA m Du rin incubation No. birds After hatch ae in days

4 1 ZAKARIA et al., Effect of ascorbic acid on embryonic development, hatch time and rowth of extended delayed placement of broiler Table 3. The effect of ascorbic acid dippin at days, 1, 19 and 11 of incubation on embryo weiht, hatchability, percentae cull chicks, unhatched e with dead or live embryos, and hatchin body weihts of commercial broiler chickens... Die Wirkun von Ascorbinsäure nach dem Dippen am und 11. Brutta auf Embryonen.ewicht, Schlupffähikeit, Anteil auselesener Küken, uneschlüpfte Eier mit toten oder lebenden Embryonen, sowie Schlupfewicht der Verkaufskuken Experi- Day of Treatment Embryo Hat eh- Cull Unhatched e with Chick hatch ment incub- of AA weiht 1 ability chicks weiht 5 ation Dead Live embryos 3 embryos () (%) (%) (%) (%) () lb Dippin (3% for 3 min.) s ' ' b Dippin b b ' (3 % for 3 min.) b Dippin " 0.l 0.3 (3% for 1.5 min.) " ' Dippin o.o o.ob b (3% for 1.5 min.) 1 Embryo weiht at 19 d of incubation (n = 0 cs per treatmcm).. The number of saleable chicks hatched as a percentac of thc treated es with livin embryos and transferred to hatc hin companmencs (n = 10, 10, 90 and 0 cs for expenmcnts, 3, and 5, respcctively) 3 Unhatched e with dead embryo either cmerin from the shell or dead in it Unhatched e with live embryo eith er emerin from the shell or still alive in it 5 Body weiht at hatchin of mixed sexes Means within a column wiilijn each cxperiment differ sinificandy (P < 0.05) decrease in body weiht at hatch and in cull chicks compared with the control (Tab. 3 ). Experimental data on the effect of dippin es in AA solution is lackin. E dippin technique before incubation of hatchin es in antibiotic solution for -0 min. is practiced as a mean of eliminatin e transmission of some disease (YoDER 198 ). Also e dippin du rin early period of incubation in very cold hormonal solution (corticosterone dissolved in absolute ethanol placed on ice) for sec. was used to study the effect of exoenous corticosterone on Lehorn chicken embryonic development (MASHALY, 1991). On the other hand, TuLLETI (1990) summarized results to indicate that temperature, durin the latter part of e incubation above 6 C and below than 1 C were detrimental to hatchability. ZAKARJA and AL-ANEz1 (1996) found that coolin es at C for h at d of incubation had no sinificant effect on hatchability, cull chicks, unhatched e with dead embryo and body weiht at hatch. The present study utilized dippin method in AA solution at C for 1.5 min. at 11 and 19 d of incubation to study the effect of AA on development of broiler chicken embryo. Dippin es in 3% AA solution for 3 min. resulted in a sinificant decrease in embryo weiht and hatchability and a sinificant increase im embryonic death. However, these effects disappeared when dippin time became 1.5 min. Ascorbic acid injection at a hih level durin later part of e incubation adversely affected some variables in previous study, such as decrease in embryo weiht and hatchability and increase in the number of cull chicks and embryonic mortality (ZAKARIA and AL-ANEZI, 1996). The findins of the present study suested that e dippin in AA solution for 3 min. durin and 1 d of incubation probably had hih level of AA. On the other hand, some stimulatory responses appeared at 11 d of incubation as a result of shortenin the dippin time to 1.5 min. suestin shorter period of time and or lower concentration of AA solution for future studies. Summary To determine the effect of ascorbic acid (AA) on embryonic development, hatch time and rowth of broiler chickens subjected to extended delayed placement, 5 experiments were conducted. In, AA treatments at d of incubation were: 1) es injected with 0.1 ml of sterile saline solution containin m of AA); ) es injected with m of AA, and 3) uninjected control. Hatchin time for each treatment was recorded at 6-h interval startin from 98 to 58 h of incubation. Additional recordin was done at 55 h of incubation. Half of chicks of each treatment at their respective hatch time were iven orally or m of AA dissolved in 0. ml sterile saline, whereas the remainin chicks were iven 0. ml sterile saline. The chicks were held in the incubator for 18 to 8 h after hatch and then placed in an uncontrolled environmental house till 9 d of ae. In Experiments, 3, and 5 es dipped in 3% solution of AA for 3 min. at and 1 d of incubation (Experiments and 3) and for 1.5 min. at 19 and 11 d of incubation (Experiments and 5). Chicks from AA treatments, particularly m AA, have hatched earlier than chicks from the control. There were sex differences in the response of AA, specially m AA durin incubation plus m AA after hatch, which resulted in reater body weihts of males; in females there was no sinificant difference. Dippin es in 3% AA solution for 3 min. resulted in a sinificant decrease in embryo weiht and hatchability and a sinificant increase in embryonic death at and 1 d of incubation, whereas these effects diminished when dippin time became 1.5 min. at 19 and 11 d of incubation. Additionally, some stimulatory responses appeared at 11 d of incubation as a result of shortenin the dippin time to 1.5 min. Zusammenfassun Um die Wirkun von Ascorbinsäure (AA) auf die Embryonalentwicklun und das Wachstum von Broilerküken zu er- A rchiv für Geflüelkunde 1/ 1998

5 ZAKARIA et al., Effect of ascorbic acid on embryonic development, hatch time and rowth of extended delayed placement of broiler mitteln, sind fünf Versuche durcheführt worden. Im ersten Versuch ist AA am. Brutta 1) in Menen von m in 0,1 ml Kochsalzlösun in die Eier injeziert worden, ) in Menen von m. 3) waren die unbehandelten Kontr. - Proben. Der Schlupf ist im 6 Std. -lntervall nach Brutstunden kontrolliert worden, zusätzlich auch mit 55 Std. Den eschlüpften Küken wurden je zur Hälfte oder m AA o ral verabreicht, während der Rest nur sterile Kochsalzlösun erhielt. Nach dem Schlupf wurden die Küken 18-8 Stunden im Brutschrank ehalten und anschließend bis zum 9. Lebenstae normal aufezoen. In den anderen vier Experimenten wurden die Bruteier in einer 3%ien AA-Lösun 3 min. lan am. und 1. Brutta edippt (Versuch u. 3) und in Versuch und 5 1,5 min lan am 19. und 11. Brutta. Die Küken mit d er AA-Behandlun, speziell bei der mdosierun, schlüpften früh er als die Kontrolle. Es ab Unterschiede zwischen den Geschlechtern. m AA während der Brut plus m AA nach dem Schlupf eraben schwerere Hähnchen, was nicht für die Hennen zutraf. Das Dippen der Eier in 3% AA für 3 min verminderte das Embryonenewicht und die Schlupffähikeit und es konnte eine sinifikante Erhöhun des E mbryonensterbens am. und 1. Brutta emessen werden. Bei einem 1.5 min-dippen am 19. und 11. Brutta war dieser Effekt eriner. Wenn das Dippen am 11. Ta unter 1,5 min reduziert wurde, ließen sich zusätzliche stimulierende Wirkunen erkennen. Stichworte Huhn, Ei, Embryo, Küken, Brut, Parameter, Behandlun, Ascorbinsäure, Wachstum Literature FA GUY, R. C., L. K. M1sRA, K. V. Vo, C. C. BLOHOWIAK and W. F. KRUEGER (1 980): Effect of delayed placement on mortality and rowth performance of commercial broilers. Poultry Sei. 59, FLETCHER, D. L. and J. A. CAsON (1991 ): lnfluence of ascorbic acid on broiler shrink and processin yields. Poultry Sei. 0, H AGER, J. E. and W. L. BEANE (1983 ): Posthatch incubation time and early rowth of broiler chickens. Poultry Sei. 6, -5. H ornig, D. and M. FRIGG (199): Effect of ae on biosy nthesis of ascorbate in chicks. Archi. Geflüelk. 3, KEsHAVARZ, K. (1996) : The effect of different levels of vitamin C and cholecalceferol with adequate or marinal levels of dietary calcium on performance and eshell quality of layin hens. Poultry Sei. 5, KRATZER, F. H., H. J. ALMQUIST and P. Vo HRA (1996): Effect of diet on rowth and plasma ascorbic acid in chicks. Poultry Sei. 5, KuHN, E. R., L. R. BERGHMAN, L. MooNs, F. VANDESANDE, E. D ECUYPERE and V. M. D ARRAS (1993): Hypothalamic and peripheral control of thyroid function durin the life cycle of the chicken in: SHARP, P. J. (Ed.) Avian Endocrinoloy, Bristol, A publication of the Society of Endocrinoloy Journal of Endocrinoloy Limited. Archiv für Geflüelku nde 1/ 1998 KUTLU, H. R. and J. M. FoRBES (1993): Chanes in rowth and blood parameters in heatsressed broiler chicks in response to dietary ascorbic acid. Livest. Prod. Sei. 36, KVTw, H. R. and J. M. FoRBES (199): Responses of broiler chicks to dietary ascorbic acid and corticosterone. Br. Poultry Sei. 35, MASHALY, M. M. (1991 ): Effect of exoenous corticosterone on chicken embryonic development. Poultry Sei. 0, M ckee, J. S., and P. C. H ARRISON (1995): Effects of supplemental ascorbic acid on the performance of broiler chickens exposed to multiple concurrent stressors. Poultry Sei., PARDuE, S. L., J. P. T HAXTON and J. BRAKE (1985) : Rol e of ascorbic acid in ehieks exposed to hi h environmental temperature. J. Appl. Physio l. 85, PARDUE, S. L. and J. P. THAXTON (1986): Aseorbie aeid in poultry) :a review. World's Poultry Sei. J., -13. RoBERSON, K. D. and H. M. EowARDS (199): Effeets of ascorbie aeid and 1,5-dihydroxyeholeealciferol on alkaline phosphatase and tibial dysehondroplasia in broiler ehiekens. Br. Poultry Sei. 35, SAS/ STAT User's Guide 1989): SAS User's Gu ide, version, 6, North Carolina, SAS Institute lne. SATTERLEE, D. G., R. B. JONES, and F. H. RYDER (199): Effeets of aseorbyl--polyphosphate on adrenoeortieal aetivation and fear-related behavior in broiler ehiekens. Poultry Sei. 3 ( TAKAHASH I, K., Y. AKJBA and M. H origuchi (1991): Effeets of supplemental aseorbie aeid on performanee, oran weiht and plasma eholesterol eoneentration in broilers treated with propylthiouraeil. Br. Poultry Sei. 3, TuLLETT, S. G. 1990): Seienee and the art of ineubation):poultry Sei. 69, 1-. W1LSON, J. X. and E. M. JAWORSKI (199): Effeet of oxyen on aseorbic aeid uptake and eoneentration in embryonie ehick brain. Neuroehem. Res. 1, WvATT, C. L., W. D. W EAVER, Jr. and W. L. BEANE (1985): lnfluenee of e size, eshell quality, and posthatch holdin time on broiler performanee. Pou!try Sei. 6, WYATT, C. L., W. D. Jr., W EAVER, W. L. BEANE, D. M. D ENBOW and W. B. GROss (1986): lnfluenee of hateher holdin times on several physioloieal parameters assoeiated w ith the immune system of ehickens. Poultry Sei. 65, YooER, H. W. Jr. (198) : Myeoplasma alliseptieum infeetion, in: H ofstad, M. S., H. J. BARNES, B. W. Calenk, W. M. REID and H. W. Jr. YoDER (eds.) Diseases of Poultry. Iowa, Iowa State University Press. ZAKARIA, A. H., and M. A. AL-ANEZ I (1996): Effeet of aseorbie aeid and coolin durin e ineubation on hatehability, eullin, mortality, and the body weihts of broiler ehiekens. Poultry Sei. 5, ZwANN, J. and K. W. LAM (199): Comparison of aseorbie aeid levels in the eye and remainder of the ehieken embryo durin development. Exp. Eye Res. 5, Korrespondenzadresse: A. H. Zakari a, Department of Anima! Scic ncc, Facu lty of Ariculture, Damascus University Damascus, Syria