monitoring environmental conditions during incubation ... - ISAH-SOC

MONITORING ENVIRONMENTAL CONDITIONS DURING INCUBATION OF
CHICKEN EGGS
Tong, Q. 1 , McGonnell, I.M 1 , Romanini, C. E.B. 2 , Exadaktylos, V. 2 , Berckmans, D. 2 , Bergoug, H. 3 , Guinebretière, M. 3 ,
Eterradossi, N. 3 , Roulston, N. 4 , Garain, P. 4 , Demmers, T. 1
1 Royal Veterinary College - Hertfordshire, UK
2 Katholieke Universiteit Leuven - Leuven, Belgium
3
ANSES – Ploufragan, France
4
Petersime NV - Zulte (Olsene), Belgium
SUMMARY
Differences in environmental conditions during incubation
may alter hatching parameters and consequently affect
chick quality and growth potential. The objective of this
research was to study the effect of high CO 2 level during
late stages of incubation. Two small scale custom built
incubators, each with a capacity of 300 eggs, (Petersime
NV) were employed. The control group experienced a
standard high CO 2 concentration program while the test
group had a lower CO 2 program during the last 72 hours
of incubation. Incubation conditions (air temperature, air
humidity, CO 2 concentration and, ventilation rate) were
controlled by the incubator controller (IRIS, Petersime TM .).
Sensors were used to monitor eggshell temperature
(OvoScan TM and Tsic 716 sensors), and hatching
movement (Synchro-Hatch TM and camera). A standardised
method (Petersime TM ) was used to score day-old chick
quality.. Results showed that chickens commenced
hatching 11 hours earlier in control group. However there
was no difference in hatchability and hatching time
between the two groups.
INTRODUCTION
Hormonal balance and CO 2 exchange are of fundamental
importance for embryonic development during incubation
and may affect survival of the embryo [2, 8]. Previous
studies have focused on the effect of high CO 2
concentration during the early and second stages of
incubation and suggest that higher levels of CO 2 can have
beneficial and persistent effects on embryonic
development during incubation by stimulating early
hatching and improving hatchability [3, 4, 5, 7, 10].
However, from biological and physiological point of view,
it is not known how environmental CO 2 levels influence
embryonic development and hatching. This study focused
on explaining why high level of CO 2 concentration during
the hatcher phase (the last three days of incubation) can
induce early piping and advanced hatching. Selected
embryonic physiological parameters were compared
between two treatments: standard incubation and low
CO 2 -steady incubation in order to understand possible
beneficial effects of high CO 2 concentration on hatching
performance.
MATERIAL AND METHODS
588 fertilized Ross 308 eggs were obtained from a local
supplier (Henry Stewart & Co. Ltd, Lincolnshire, UK). The
eggs were weighed and numbered before setting. Eggs
were incubated in two small scale custom built incubators
(Petersime NV, Zulte, Belgium). Each incubator was able
to set 300 eggs separately in 2 trays. Incubation
conditions (machine temperature, humidity, CO 2
concentration, and ventilation rate) were continuously
monitored and controlled by the incubator controller
(IRIS, Petersime TM ). CO 2 patterns of control group and
test group were programmed and achieved by adjusting
ventilation. The control group experienced the standard
program with four phases of high CO 2 levels: reaching
0.7% at incubation time 18day18hours (18:18),
maintaining 1% 12 hours after onset of IP-step , and
reaching 0.8% and 0.7% after 2hours and 6 hours of H
(hatch) step initiation, respectively. In the test group CO 2
concentration was maintained at 0.3%. Individual eggshell
temperature (EST) of 10 eggs per incubator was
measured every 5 minutes by temperature sensors
(Tisc TM - 716, IST, Switzerland) during the entire
incubation process. After transfer to hatcher baskets on
day 18, the 10 eggs with temperature sensors were
located in a designated area of the upper basket and the
hatching process of the entire basket was monitored by
camera (CCD digital colour camera, VDC 413) attached to
the inside top of the incubator. Images were captureed
every minute and saved automatically on a PC. All eggs
were candled during transfer and those with evidence of a
living embryo were transferred from the turning trays to
hatching baskets. After 512h (21:08) of incubation
machines were stopped. The number and quality of
hatched chicks were recorded and scored by a standard
method (Petersime TM ). Hatchability was determined after
hatch. The unhatched eggs were opened and checked.
Data were expressed as means ± SE and differences
between control and test groups at the same incubation
time were analysed using SAS 8.01. The variables of EST
were analysed by an analysis of variance (ANOVA) using
the GLM procedure (SAS Institute Inc., 1990), with ‘egg

categories’ as the main effects. A significance level of 0.05
was used. Means were compared using Student-Newman-
Keuls multiple range (SNK) test contrasts (SAS Institute
Inc., 1990).
RESULTS
1. Hatching parameters
Hatching parameters are summarized in Table 1.
Hatchability was similar for both groups. When day-old
chick quality scores were taken into account, the
percentage of first class chick in control group was
significantly higher than that in test group.
Table 1. Fertility, hatchability and first class chick proportion
Test Group
Fertility 1 (%) 90.48 94.88
Hatchability 2 (%) 74.18 75.19
First Class Chick 3 (%) 86.19 98.97
1
Fertility expressed as percentage of eggs set.
2
Hatchability expressed as percentage of fertile eggs.
3
First Class Chick expressed as percentage of hatching chicks.
control Group
2. Eggshell temperature (EST)
The status of the eggs with attached temperature sensors
was determined after hatch. There were three categories
of eggs: unfertilized (UN), dead embryos (D), and
hatching chicks (H). The EST of 3 categories of eggs
showed no significant difference during the first 11 days.
However, egg status showed difference in EST at day 18,
19 and 20 (Table 2). The EST of hatching eggs is higher
than the EST of eggs with dead embryos and unfertilised
eggs (P ≤ 0.05).
Table 2. Eggshell temperature of three egg categories
Incubation time(day) H-mean D-mean UN-mean
18 37.3±0.12 a 36.6±0.12 b 36.43±0.15 b
19 38.32±0.13 a 37.64±0.13 b 37.47±0.16 b
20 37.7±0.12 a 37.09±0.12 b 36.97±0.15 b
3. Hatching process
The hatching time of first chick in the control group is at
day 19 and 11 hours (19.11) compared to 19.22 in the
test group (11 hours later (). Most chicks had hatched by
20.17 in the control group compared to 21.06 in the test
group. Thus the total length of hatching times (hatch
window) for control and test groups are 30 hours and 32
hours, respectively?
Figure 3. Number of hatching chicks at different incubation time
DISCUSSION
Temperature sensors capture the EST during the complete
incubation and show the division of EST of three egg
statuses (unfertilised, dead and hatching). Due to an
increased metabolism, piping action and hatching
movement, the embryo increases heat production at the
latter part of incubation which maintains the eggshell
temperature during transfer, at day 19 and 20. Thus EST
is significant lower in eggs housing dead embryos and

unfertilised eggs at this time. Hatching times within
incubators vary greatly, with an average hatching window
estimated between 32 and 48 hours [6, 9]. Cameras
provided a tool to monitor the hatching process without
opening the door of incubator. The end of hatch process is
marked by the time when the majority of chickens have
hatched and the incubator is stopped. It may also be that
incubation management, with regards to ending the
incubation at the appropriate time, may optimize
hatchability and chick quality. Previous research has
reported that an earlier hatch does not result in a smaller
duration of the hatching process[1].In this study, the
hatching window of control group is only slightly shorter
than the test group, even though the hatch started 11
hours early.
CONCLUSIONS
Corticosterone levels increased significantly at the end of
incubation and can stimulate the hatch process. High CO 2
level of incubation condition can stimulate corticosterone
and this may explain why the chicks in the control group
hatched early and have higher quality compared with the
test group. Further research is needed into the impact of
CO 2 concentrations on hormones levels and hatching
windows.
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