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EFFECTS OF VARIABI"E INCUBATING TEMPERATURES, NUMBER' AND PROXIMITY OF EGGS DURING HATCHING ON THE HATCHABILITY OF CHICKEN EGGS F. G. PROUDFOOT Research station' ';!:l,io9l'f."'jt:';nf;,"';:lj:;,y;'fr:r"";t,mribution no' 447' Can. J. Anim. Sci. Downloaded from www.nrcresearchpress.com by 48.5.3.83 on 04/8/8 ABSTRACT An experiment involving 5760 eggs was con- Jamesway 5 incubators,_ were designed to ducted- to evaluate the ifiect on hatchability evaluate the effect of () the number of- eggs of periodic reductions in incubation tempera- per hatching tray and () the closeness of eggs tur6s caused by setting two-sevenths of the during hatching on hatchabilily. Although eeg incubator capacityweekly, using "cold" ( C) numbers varied from 30 to 50 eggs per tray' eggs vs. "pre-warmed" (37C) eggs. No overall there was no evidence that either the number deirimentil effect could be--demonstrated of eggs per tray or separation vs. contact despite a temporary 5 degrees C reduction in between eggs during hatching had any effect incubator air temperature. Three other experi- on hatchability. ments, involving 4080 embryonated eggs in RESUME Les chercheurs ont effectu6 une exp6rience dans 5 incubateurs Jamesway, et_ portant sur 5760 oeufs, afin de d6terminer les efiets sur 4080 oeufs il embryon d6veopp6, aln de sur le coefficient d'6closion, des abaissements mesurer les efiets: () du nombre d'oeufs par p6riodiques de la temp6rature d'incubation, plateau d'6closion et,().la densit6 des oeufs itouoqrier pui timise en place hebdomadaire iu cours de l'incubation sur la facult6 -tt'oeufi -raison "fr6ids" ( C) b de /7 de la d'6closion. Bien que le nombre d'oeufs par capacit6 de f incubateur, comparativement i plateau aient vari6 de 30 d 50,,on n'a -pu de^s oeufs "pr6chauff6s"'il 37 C. Aucun effet -obtenir aucune certitude. que- le nombre J6favorable^ global n'a pu 6tre d6rnontr6 en d'oeufs par plateau, ou leur s6paration au d6pit d'une diminution t6mporaire de 5 d6gres cours de I'incubation, compa,rativement au C ae la temp6rature de I'air de l'incubateur. contact, aient eu un effet quelconque sur la Ils ont congu irois autres exp6riences, effectu6es facult6 d'6closion. INTRODUCTION Frequently incubator temperatures ale varied by the introduction of "cold" eggs either weekly or biweekly to the incubator chamber in which eggs set previously are under incubation. The question arises whether this variation in incubating environmental temperatures has an efiect on hatchability. Some field observations indicate if eggs are in contact with each other during the later stages of incubation, hatchability will be higher than when eggs are separated from each other. lt has also been suggested that the concentration of eggs on the hatching tray may affect hatchability. This is a report of experiments designed to investigate the effects on hatchability of: () fluctuating incubation temperatures resulting from introducing "cold" eggs to incubator chambers containing eggs under incubation; () different numbers of eggs on the hatching tray; and (3) eggs separated vs. in contact on the hatching tray. MATERIALS AND METHODS Eggs were collected for experiments,, and 3 from a commelcial strain-cross of meat parent birds. Collection of eggs for experiment commenced when the parent birds were 300 days of age and experiments and 3 commenced when the flock was 440 and 447 days of age, respectively. In experiment, seven Jamesway 5 incubator units designated A, B, C, D, E, F, and G were involved. Units A and B were used to set four trays in each Can. J. Anin. Sci.5 459-464 (Sept. 97) 459

460 canadian JouRNAL of ANTMAL scrence Can. J. Anim. Sci. Downloaded from www.nrcresearchpress.com by 48.5.3.83 on 04/8/8 incubator of 80 eggs each week for 5 consecutive weeks. The eggs were taken directly from an e-eg cooler operated at l C each week and placed in the incubator at once. Unit C was used to prewarm eight trays each containing 80 eggs for 6 hr prior to setting four trays in each of units D and E. Unit F was used to hatch eggs from units A and B and unit G was used to hatch eggs from units D and E. Data from the st, 4th, and 5th weekly settings were not included. Data from the two middle weekly settings were used to evaluate the effect of these treatments. Data from the first settings were not included as the incubator only contained four trays of prior set eggs when the temperature treatments were executed at the time of the second setting. Data frorn the fourth setting were not included because these eggs were temperature-treated only once, and the fifth setting was not temperature-treated because no further settings were made. Thus, hatching eggs were introduced weekly and set in incubators that had eggs under incubation for 7 and 4 days. Experiment was designed to study the effect on hatchability of difierent numbers of eggs in the hatching tray separated and in contact. Two thousand eggs were collected the day prior to placing them under incubation in a Jamesway 5 incubator. On the 8th day of incubation eggs were candled and infertile eggs and eggs containing dead embryos were discarded. Embryonated eggs were transferred to hatching trays as follows: ( ) four trays each with 30 eggs in contact with each other and four trays each with 30 eggs separated on the tray; () two trays each with 60 eggs in contact and two trays with 60 eggs separated; and (3) two control trays containing 50 eggs in contact. Tray positions in the incubator were allocated at randorn. The area of each hatching tray was 4375 cm'. For experiment 3, eggs were collected over a 3-day period and incubated in a Jamesway 5 unit. On the 8th day of incubation eggs were candled and infertile eggs and eggs containing dead embryos were removed and eggs containing live embryos were transferred to three incubator units. Embryonated eggs were allocated at random to 4 trays each containing 30 eggs. In one-half of these trays eggs were spread over the trays in such a way to avoid eggs being in contact with each other. In the remaining trays the 30 eggs were kept in contact by using a wire fabric partition. Each unit contained seven trays with eggs in contact and seven trays with eggs separated. Experiment 4 was designed to further elucidate the effects on hatchability of eggs separated and in contact during hatching. In experiment 4 eggs were obtained from two commercial meat-type strain-crosses when they were 70 days of age. On the 8th day of incubation, eggs containing live embryos were transferred to trays in each of five incubator units with 30 eggs per tray. One-half the trays in each unit contained eggs separated on the tray and^tne eggs in the remaining trays were kept in contact by the use of a wire fabric partition. Thus, each incubator unit contained three trays of each treatment for each straincross. In all experiments cheese cloth was spread on the floor of the tray prior to placing eggs in the hatching tray. For experiment t hatchability was based on the number of eggs set but for experiments,3, and 4 hatchability was based on fertile eggs transferred on the 8th day of incubation. Percentage data were converted to angles for analysis of variation for all experiments.

PROUDFOOT-HATCHABILITY OF CHICKEN EGGS 46r Can. J. Anim. Sci. Downloaded from www.nrcresearchpress.com by 48.5.3.83 on 04/8/8 RESULTS AND DISCUSSION The weekly introduction of "cold" eggs (from an egg storage temperature of C) initially reduced air temperature within the incubators from 37.4 C to 3.4 C. It required 3 hr for the temperature to return to 37.4 C (Fig. ). These results provide evidence that the variation in incubator temperature did not result in an overall detrimental effect. The statistical analyses also revealed that hatchability differed between the two incubator units (Tables and 5). These results agree with Landauer's (967) review in which he indicated that periodic cooling at room temperature during incubation had no practical effect on hatchability, although a number of investigators continue to claim advantages from regular periods of cooling. It is assumed that although the incubator air temperature was altered considerably by this treatment, the embryonic temperature change was much less. Results of experiment (Tables and 5) demonstrated the absence of difierential hatchability when either 30, 60, or 50 eggs were arranged either in contact or spread out cver the hatching tray. There was some indication that F 3 30 TIME {MINUIES) Fig.. Increase in incubator temperature with time following the introduction of four trays of eggs directly from an egg storage operated at l C to a Jamesway 5 nnit containing eight trays of eggs already under incubation. (The graph is the average of the temperature increase of two incubator units.) Table. Effects of variable vs. constant incubation temperatures on percent hatchability of chicken eggs in experiment Replicates Incubator Settingsf unit \{ean Overall B B D E D E 80.9 8.6 8.r 78.9 79.3 85.4 77. Variable,incubation temperatur es 77.8 83.8,t 85.0 8.0 83.8 8.6 799 866 79.3 C on stan t i ncu bat ion Ie m peral ures 79.4 80.6 78.6 8r.7 87. 78.6 83. 8 t7t I a I 8r.7 8 8.9 79. 84. 80. 8.8 8.0 70, 80.5 80.6 fdata from settings, 4, and 5 were discarded because eggs of the first setting lvere temperature-treated when incubation contained only four trays of eggs rather than eight trays; eggs of the fourth setting were only subjected to one coldtemperature treatment and eggs of the fifth setting, being the last eggs set, $'ere not subjected to a difierential temperature treatment.

46 CANADIAN JOURNAL OF ANIMAL SCIENCE Table. Percentage hatchability of 30 and 60 eggs in close proximity vs. separated on the hatching tray in experiment Eggs per hatching trayf 30 60 50 on hatching tray 9. 93.8 Close contact on hatching tray 95.8 95.0 93.6 Can. J. Anim. Sci. Downloaded from www.nrcresearchpress.com by 48.5.3.83 on 04/8/8 f50 eggs filled the hatching tray to capacity. Table 3. Percentage hatchability of eggs in contact and separated during hatching in three incubator units in exoeriment 3 Replicates Unit Treatment Combined 96 7 933 900 9.4 86.7 00.0 933 93.3 90.0 83.3 909 90.0 90.5 3 00.0 93.3 00.0 90 0 96 7 94.8 00.0 93 3 93.3 90,0 93.8 Overall 97 9.5 Table 4. Percentage hatchability of eggs collected from t*'o commercial meat strain-crosses hatched in contact and separated on the incubator hatching tray in experiment 4 Replicates Incubator unit Treatment Cornbined 5 Overall Cor.rtact lo. I 66.7 70.0 Strain A Stra'in B 93. 900 /J.J 900 867 933 83.3 83.3 700 93.3 lo. I 833 90. 87. 8 88.8 87.8 87. 8 8. 85.5 /J.O 78.9 889 83.4 874 97. 88.9 88. S 84.4 85.6 89.0 85.8 868

PROUDFOOT-HATCHABILITY OF CHICKEN EGGS 463 Table 5. l{ean squares of the analyses of var.iance of percentage hatchability (converted to angles) from experiments 7,, 3, and 4 Source of variance df Mean squares Can. J. Anim. Sci. Downloaded from www.nrcresearchpress.com by 48.5.3.83 on 04/8/8 Exp Setting days Temp Setting X temp Between incubators/temp Setting X incubators/temp \\rithin incubators/temp Exp 30 vs. 60 eggs per tray vs. contact on the tray 30 vs. 60 eggs X sep. vs. cont. Residual Exp 3 vs. contact on the tray Incubator units Sep. vs. cont. X incub. units Residual Exp 4 Strains-crosses vs. contact on the tray Incubator units Cross-str. \ sep. vs. cont' Cross-str. X incub. units Sep. vs. cont. X incub. units Crbss-str. X sep. vs. cont. X incub. unit Residual xsignificant at tlne 5/p levei. 4 I I I 36 4 4 4 40.0t7 0.000 0.770 7. 6+* 8.5007 4.0850 0.5995 7.645 0.5996 9.868 0.6537 0.4t40 8.0050 33.866 76.59 3.780 5.9353 6.339 35.4798 6.6440 9.4860 35.068 eggs trayed in close proximity hatched better than eggs placed spread out on the hatching tray but this difierence was not statistically significant. Experiments 3 and 4 were initiated to examine this problem further. Results of experiment 3 (Tables 3 and 5) demonsttate that when 30 eggs were set per tray they hatched equally well whether they were in close proximity during hatching oi spread separately ovel the hatching tray. In this experiment there was no significant difierence between the three incubator units. The results of experiment 4 are presented in Tables 4 and 5 and further substantiate results obtained from experiments and 3. In this experiment eggs separated on the hatching tray hatched the same as eggs in contact on the hatching tray. Eggs from two cornmercial broiler strains were used in experiment 4 and both genotypes reacted to this treatment in a similar manner. Vince and Cheng (,970) reported that proximity of eggs afiected the. time of hatch. This phenomenon was not evaluated in this study; however, this may be of little practical importance if hatchability is unaffected. It is concluded that variable incubation temperatures resulting from the weekly setting of two-sevenths of the incubator capacity had no significant overall effect on subsequent hatchability. Evidence is provided that the number of hatching eggs per tray had no effect on hatchability. Contrary to reports frorn the field

Can. J. Anim. Sci. Downloaded from www.nrcresearchpress.com by 48.5.3.83 on 04/8/8 464 CANADIAN JOURNAL OF ANIMAL SCIENCE it was found in these experiments that eggs hatched equally well whether placed on the hatching tray either in contact or separated. I,ITERATURE CITED LANDAUER, W. 967. The hatchability of chicken eggs as influenced by environment and heredity. Conn. Agr. Exp. Sta. Monogr.. VINCE, M. A. and CHENG, R. 970. The retardation of hatching in Japanese quail. Anim. Behav. 8: l0jl4.

Can. J. Anim. Sci. Downloaded from www.nrcresearchpress.com by 48.5.3.83 on 04/8/8 This article has been cited by:. Christine M. Mather, K. F. Laughlin. 976. Storage of hatching eggs: The effect on total incubation period. British Poultry Science 7:5, 47-479. [Crossref]