ArticlePDF Available

Abstract

Ducks are waterfowl belonging to the Anatidae family of cosmopolitan distribution. In duck production systems, obtaining ducklings at one-day-old is determinant for the productive chain. The egg production in some species of ducks reaches about 250 to 300 eggs per year. Obtaining one-day-old ducklings can be done by natural incubation with a broody female duck or artificially in an incubator. During artificial incubation, fertility and hatchability are the most important indicators that must be controlled, because they influence the supply of ducklings to the farm. Many factors are related to fertility and hatching, such as environmental conditions, production system, season, nutrition, management of broodstock, storage time of egg and cleaning of eggs before the incubation. According to some reports, Pekin eggs have greater hatchability than Muscovy eggs. The eggs of Muscovy have presented values lower than 22.7% of hatchability. The hatchability of Pekin duck eggs was 78.0% in the spring, while in summer it was around 46.5%. The best hatchability is observed during the winter (57.68%), as in the summer it decreases to 54.14%. The reproductive characteristics of flocks, age, external and internal quality of the egg, male female relation, and presence of lethal genes are factors that directly involve breeders. Larger sexual ratios between males and females of 1:4.3 to 1: 10 cause reduced egg fertility from 75.9% down to 49.6%. Successful production of day-old ducklings starts with the proper selection and management of breeding stock, proper post-lay handling of fertile eggs and the correct incubation process. There are different methods used to improve the hatchability such as dipping eggs in nutrients during the incubation period.
Fertility and hatchability in duck eggs
M.E. ABD EL-HACK
1
*, C.B. HURTADO
2
, D.M. TORO
3
, M. ALAGAWANY
1
*,
E.M. ABDELFATTAH
4
and S.S. ELNESR
5
1
Poultry Department, Faculty of Agriculture, Zagazig University, Zagazig 44511,
Egypt;
2
Department of Livestock Sciences, Faculty of Veterinary Medicine and
Zootechnic, University of Córdoba, Monteria 230002, Colombia;
3
Laboratory of
Animal Nutrition, Faculty of Natural Sciences, Autonomous University of
Queretaro, Queretaro 76230, Mexico;
4
Department of Animal Science, University of
California Davis, Meyer Hall, One Shields Avenue, Davis, CA 95616. USA;
5
Poultry
Production Department, Faculty of Agriculture, Fayoum University, Fayoum,
63514, Egypt
*Corresponding author: m.ezzat@zu.edu.eg; dr.mahmoud.alagwany@gmail.com
Ducks are waterfowl belonging to the Anatidae family of cosmopolitan distribution.
In duck production systems, obtaining ducklings at one-day-old is determinant for
the productive chain. The egg production in some species of ducks reaches about
250 to 300 eggs per year. Obtaining one-day-old ducklings can be done by natural
incubation with a broody female duck or articially in an incubator. During
articial incubation, fertility and hatchability are the most important indicators
that must be controlled, because they inuence the supply of ducklings to the
farm. Many factors are related to fertility and hatching, such as environmental
conditions, production system, season, nutrition, management of broodstock,
storage time of egg and cleaning of eggs before the incubation. According to
some reports, Pekin eggs have greater hatchability than Muscovy eggs. The eggs
of Muscovy have presented values lower than 22.7% of hatchability. The
hatchability of Pekin duck eggs was 78.0% in the spring, while in summer it was
around 46.5%. The best hatchability is observed during the winter (57.68%), as in
the summer it decreases to 54.14%. The reproductive characteristics of ocks, age,
external and internal quality of the egg, male female relation, and presence of lethal
genes are factors that directly involve breeders. Larger sexual ratios between males
and females of 1:4.3 to 1: 10 cause reduced egg fertility from 75.9% down to 49.6%.
Successful production of day-old ducklings starts with the proper selection and
management of breeding stock, proper post-lay handling of fertile eggs and the
correct incubation process. There are different methods used to improve the
hatchability such as dipping eggs in nutrients during the incubation period.
Keywords: ducks; fertility; hatchability; eggs; incubation
© World's Poultry Science Association 2019
World's Poultry Science Journal, Vol. 75, December 2019
Received for publication November 3, 2018
Accepted for publication September 4, 2019 1
doi:10.1017/S0043933919000060
https://www.cambridge.org/core/terms. https://doi.org/10.1017/S0043933919000060
Downloaded from https://www.cambridge.org/core. UC Davis, on 22 Oct 2019 at 03:51:15, subject to the Cambridge Core terms of use, available at
Introduction
Ducks are waterfowl that belong to the Anatidae family. Other waterfowl such as loons,
grebes, gallinules and coots may be confused with this species (Idahor et al., 2015;
Ericson et al., 2017; Farghly et al., 2018a) but do not represent a monophyletic group;
therefore, swans and geese are not considered ducks. They are distributed throughout the
world, except in Antarctica (Idahor et al., 2015), due to their adaptability to different
environments. Because of the variable market demand for a one-day-old chick by the
duck industry, fertility and hatchability are important economic factors which represent
the major components of reproductive performance and are sensitive to environmental
and genetic factors (Widiyaningrum et al., 2016).
Fertility is dened as the percentage of embryonated eggs after three days placement in
the incubator; meanwhile, hatchability is the percentage of fertile eggs that hatch
(King'ori, 2011; Taplah et al., 2018). Fertility and hatchability are affected by genetic
and non-genetic factors. For a particular variety, non-genetic factors have a greater
inuence on fertility and hatchability in production (King'ori, 2011), Including
management of the breeder, egg quality, and incubation processes. The management
of breeding stock includes genetic selection (Drouilhet et al., 2014), age of the
breeders (King'ori, 2011), season and feeding (King'ori, 2011), breeding system and
breeding technology (Weis et al., 2011) and egg quality (Hester, 2017). The objective
of the following review was to provide advanced information about the factors that affect
fertility and hatchability of duck eggs and ways to improve them.
Fertility
Fertility can be affected by the quality of broodstock, male:female ratio, environmental
temperature, storage time and housing systems. Brillard (2003) stated that fertility
depends on the ability of females to ovulate, store sperm and provide an appropriate
environment for the formation and development of the egg. Likewise, Brillard (2003) and
Mohan et al. (2018) reported that the quality and quantity of semen deposited by the
male were important to obtain good fertility. However, there are differences between
duck breeds.
Muscovy ducks age inuences the reproductive characteristics of both females and
males (Yakubu, 2013). For ocks from the same breed, differences in fertility have been
reported for different batches of eggs. In Muscovy ducks, the highest fertility is obtained
at the peak of posture, compared to the moments before or after the peak of posture
(Nickolova, 2005). Genitalia of waterfowl is more complicated than chickens, making the
fertility issue more prevalent in ducks than in chickens, as well as the issue of sexual
dimorphism in body size in some breeds of ducks and crossbreeding (Yakubu et al.,
2015).
The male:female ratio in all poultry species plays an important role in achieving greater
fertility. For Muscovy ducks a ratio of one drake to ve ducks is used according to Idahor
et al. (2015) and one to four according to Nickolova (2005) and Alonso-Alvarez (2006).
In Muscovy ducks, a ratio of one to six has been used satisfactorily where there is a
shortage of males (Banerjee, 2013). However, larger sexual ratios of 1:4.3 to 1:10 cause a
reduced egg fertility from 75.9% down to 49.6% (Nickolova, 2005), which corresponded
with a loss in fertility from 97.09% to 93.41% when the sex ratio was increased from 1:5
to 1:8. In Khaki Campbell ducks, Giri et al. (2014) studies the ideal mating sex ratio for
production of fertile eggs under intensive rearing and concluded that a 1:5 sex mating
ratio was ideal for better fertility and hatchability.
2 World's Poultry Science Journal, Vol. 75, December 2019
Fertility and hatchability in duck: M.E. Abd El-Hack et al.
https://www.cambridge.org/core/terms. https://doi.org/10.1017/S0043933919000060
Downloaded from https://www.cambridge.org/core. UC Davis, on 22 Oct 2019 at 03:51:15, subject to the Cambridge Core terms of use, available at
An increase of the environmental temperature above the optimal ranges of thermal
comfort in poultry affects productive performance of breeders. According to Chowdhury
et al. (2004), heat stress causes a decrease in the number of germ cells, ovular release,
fertilisation and survival capacity of the embryo and abnormalities in sperm of the
Northern Pintail duck (Penfold et al., 2000). The latter decreases deposition of sperm
in the host gland in the reproductive system of female (Brillard, 2003; Abd El-Hack et
al., 2018). Fertility was signicantly higher at months from January to May as compared
to June to August months and was signicantly lowered by 9.70%, 12.72% and 14.29%
in Summer as compared to Autumn, Winter and Spring season, respectively (Awad,
2013)
The storage time before the incubation of Pekin duck eggs has a signicant effect on
their fertility, hatchability and early embryo mortality (Waehner et al., 2015). Reyna and
Burggren (2017) reported a decrease in the fertility of duck eggs stored for more than six
days from laying to incubation.
Housing system inuences the fertility of ducks, allows mass mating and provides
access to swimming, which signicantly increases the fertility rate as ducks are waterfowl
by nature and prefer to mate in water (Ojewola, 2006). However, egg weight linearly
improves fertility; in Khaki Campbell ducks, the egg weight increased from 60 g to 75 g
when they had water access, which positively affected egg fertility (Giri et al., 2014).
Hatchability
Factors attributed to the breeding birds, such as genetic selection, management and
feeding, handling and storage of eggs and conditions inside the incubator can
inuence the hatchability of duck eggs. Archer et al. (2017) and Ramli et al. (2017)
stated that the temperature, relative humidity, ventilation and turning of the eggs
throughout incubation and hatching were environmental factors that can modify
hatchability.
BREEDER MANAGEMENT
Breeders must use breeds with good genetic characteristics at optimal ages to obtain
high fertility, hatchability and growth performance of progeny. The time of year and the
feeding conditions play an important role in the development of the embryo, before and
after incubation.
Genetic characteristics can inuence the productive indicators of different breeds of
ducks in varying ways. The Muscovy lineages, compared to the Pekin duck, show higher
mortality due to adhesion to the egg shell and for normal ducklings, however, Pekin duck
eggs have better hatchability than Muscovy eggs (Rashid et al., 2009). The eggs of the
Muscovy such have shown less than 22.7% of hatchability (Ali et al., 1989). The fertility
and hatchability of laying Brown Tsaiya ducks were increased when a genetic selection
was made and one articial insemination per week was combined with Muscovy semen
(Cheng et al., 2002).
AGE
The age of female ducks has more inuence on fertility than age of males (Brommer
and Rattiste, 2008). After 24 days of incubation, the relative weight of the yolk sac, with
respect to total egg weight, increased in hens at 36 weeks compared with Pekin ducks at
26 and 31 weeks of age (Applegate et al., 1998). On the other hand, increasing the age of
the female decreases the functioning of the sperm storage tubules, leading to problems in
the reproductive system which inuences egg quality.
World's Poultry Science Journal, Vol. 75, December 2019 3
Fertility and hatchability in duck: M.E. Abd El-Hack et al.
https://www.cambridge.org/core/terms. https://doi.org/10.1017/S0043933919000060
Downloaded from https://www.cambridge.org/core. UC Davis, on 22 Oct 2019 at 03:51:15, subject to the Cambridge Core terms of use, available at
In addition, the age of ducks affects the external and internal quality of eggs,
inuencing both hatchability and fertility. The ratio between yolk and albumin
decreased with increasing age of the birds (Peebles et al., 2001). Larger eggs have
comparatively less shell area per unit of interior weight than smaller ones, therefore,
those from older broodstock have less weight when calculated in grams and more in
percentage than the eggs of younger broodstock (Onasanya et al., 2013). Age affects the
deposition of calcium and minerals in the shell (Onbaşılar et al., 2014). The shell allows
gaseous exchange and loss of moisture from the egg, and poor shell quality results in
excessive loss of relative humidity during incubation (Peebles et al., 2001).
SEASON
The season when laying takes place affects fertility of ages and hatchability of
ducklings, due to differences in temperature, wind speed, rainfall and relative
humidity (Buhr, 1995; Farghly et al., 2018b; Li et al., 2018). Chowdhury et al.
(2004) observed a high signicance between the month and hatchability of Pekin
duck eggs, where the hatchability in January was 59.54 ± 0.79%, but in July it
decreased to 48.27 ± 0.79%. The best hatchability of Pekin duck eggs is observed
during the winter (57.68 ± 0.59%), but during the summer it decreases to 54.14 ±
0.59%, and the lowest values are found in the monsoon or rainy season (49.13 ±
0.59%) (Chowdhury et al., 2004). Hatchability of duck eggs showed the highest value
in March (65.21%), but the lowest value (34.96%) was observed in August (Awad,
2013). Fertility and hatchability were lower in the summer months compared to other
seasons due to high environmental temperature that causes a decrease in the reproductive
efciency in both male and female ducks.
NUTRITION
During egg formation, essential nutrients are deposited for the development of embryo
during the incubation period and form reserves for the developing embryo until the rst
meal becomes available to the young birds (El-Kholy et al., 2019; Saeed et al., 2019).
The nutrients are used for tissue formation, heat generation and muscle activity, and are
stored in both albumin and yolk (Uni et al., 2012; Onbaşılar et al., 2014). Egg albumin
from eggs from Pekin ducks is mainly water (85.7 to 88.1%) containing 10.9% to 13.1%
water-soluble proteins and represents from 53.0% to 55.6% of the total egg content.
Although the yolk only represents 31.3% to 33.9% of the egg content and 41.7% to
44.1% is water, it has higher protein reserves (17.3% to 17.8%), lipids (35% to 38.4%)
and minerals (Yair and Uni, 2011).
Nutrient deciencies impede the proper development of embryos, reduce hatchability
and increase embryonic death, in addition to causing disorders of the musculoskeletal
system, immune system and cardiovascular system (Uni et al., 2012). The nutrients in the
egg determine the weight of the duckling at birth, body size and hatchability. Therefore,
feeding ducks correctly can increase deposition of nutrients in the egg, without causing
any change in weight of the broodstock, which are important factors to consider to avoid
low quality ejaculation and ovulation and, at an extreme, early ovarian and testicular
regression (Brillard, 2003).
Certain nutrients and food ingredients have adverse effects on the quality and quantity
of eggs produced by ducks. Anti-nutritional factors, such as gossypol from cotton seed
meal, cause infertility in males manifested as immobility of sperm caused by damage to
the mitochondria located in the tail of sperm, and extensive damage to the germinal
epithelium (Randel et al., 1992). Increased consumption of gossypol causes increased
permeability of the yolk sac membrane which leads to excessive pigmentation of the
albumin, known as pink diseaseor white albumen which is mottled or gummy. It is
4 World's Poultry Science Journal, Vol. 75, December 2019
Fertility and hatchability in duck: M.E. Abd El-Hack et al.
https://www.cambridge.org/core/terms. https://doi.org/10.1017/S0043933919000060
Downloaded from https://www.cambridge.org/core. UC Davis, on 22 Oct 2019 at 03:51:15, subject to the Cambridge Core terms of use, available at
necessary for producers to constantly update feeding standards and include new
recommendations to ensure the quantity and quality of food necessary to the layer ducks.
Egg factors
Eggs are normally fertile four days after the deposition of the semen inside the female,
and in this period all necessary components for the development of embryo until the birth
should be present in the egg. Under normal circumstances, infertility is due to different
factors related to the management of the broodstock and environmental conditions, since
these are related to modications in the physical and chemical characteristics that reduce
embryonic development and hatching of good quality ducklings (Narushin and Romanov,
2002).
The management of broodstock plays an important role to ensure a good hatchability,
breed used, season, health, and nutrition, also size, weight and quality of egg, in addition
to the duration and storage conditions (Wilson, 1991; Onasanya et al., 2013). The quality
of eggs for incubation is determined by both external and internal characteristics,
however, there are other factors that prevent hatching, such as the inheritance of
lethal genes, lack of nutrients and sudden variations in incubation conditions
(King'ori, 2011).
EGG QUALITY
Egg quality has a signicant effect on hatchability, as conditions of the
microenvironment during the storage process and early incubation modify both the
external and internal quality of eggs (Narushin and Romanov, 2002). External
characteristics such as weight, index form (described as maximum breadth to length
ratio), shell thickness, porosity, surface quality of the shell and resistance to breakage
have been measured (Toro et al., 2015). Internal quality is determined by the height of
the dense albumen and the yolk, in addition to Haugh Units. Haugh units are calculated
as:
HU=100 log (H+7.571.7W
0.37
)
where HU=Haugh units, H=albumin height and W=egg weight (Toro et al., 2015).
Heavier eggs are more likely to hatch than those of low weight; however, there are
contradictions about the weight of eggs that are not within the average values for
incubation (King'ori, 2011). An increase in weight, shell thickness and internal
contents of eggs leads to a higher total weight, which in turn reects more reserves
of nutrients and energy (Toro et al., 2015). Light weight eggs have relatively shorter
incubation times (Weis et al., 2011) and the weight of hatchlings is higher from large
eggs. It is important to note that, during incubation, larger embryos produce a greater
amount of heat, which requires good ventilation to maintain the correct temperature
(Jibrin et al., 2011).
Likewise, egg size affects hatchability. Wilson (1991) and Weis et al. (2011) found that
medium-sized eggs from Muscovy ducks had better hatchability than small eggs. In this
sense Demirel and Kırıkçi (2009), found a greater increase in yolk compared to albumin
as the egg size increased, which could be a major inuence.
With longer storage time, HU decreases and pH of the albumin increases, apparently
due to loss of water (Martínez et al., 2014). Elibol et al. (2002) stated that the low pH in
fresh eggs did not affect fertility and hatchability, however, other authors indicated the
opposite, and perhaps this difference may be due to different ock age (Benton and
Brake, 1994).
World's Poultry Science Journal, Vol. 75, December 2019 5
Fertility and hatchability in duck: M.E. Abd El-Hack et al.
https://www.cambridge.org/core/terms. https://doi.org/10.1017/S0043933919000060
Downloaded from https://www.cambridge.org/core. UC Davis, on 22 Oct 2019 at 03:51:15, subject to the Cambridge Core terms of use, available at
EMBRYO SURVIVAL
According to Kuurman et al. (2003), mortality describes a curved, diphasic Weibull
distribution, due to the peaks of mortality in the rst and last third of incubation. The
survival of the embryo does not only depend on environmental conditions before and
during incubation, factors related to the genotype of the dam and the sire, mainly the
dam, affects the survival of the duckling within the egg. Chromosomal aberrations and
lethal genes acquired from the sire and dam can cause high percentages of early
embryonic mortality (Liptoi and Hidas, 2006). The stage of development decreases
the heritability of the susceptibility to embryonic death, from 0.09 for early mortality
to 0.05 for late mortality, based on the parent component and from 0.25 to 0.18 based on
the dam component (Beaumont et al., 1997). In this sense, Bennewitz et al. (2007)
reported low direct heritability of hatchability, based on linear and threshold models
respectively, with hatching capacity treated as a trait of the dam.
EGG STORAGE
The microenvironment conditions during storage, storage time and position of the eggs
on the incubation tray are important to guarantee a protable production of ducklings,
especially for production in the tropics and subtropics. To avoid the effect of heat stress
on the embryo during storage, temperature should be 13°C (55°F) and never higher than
24°C, and relative humidity should be less than 75% but higher than 40% (Buhr, 1995).
Eggs stored under refrigeration should be placed for 4 h at room temperature before
incubating (Onbaşılar et al., 2007). Onbaşılar et al. (2007) reported that hatchability was
lower and early embryonic death rate was the highest in eggs stored for 11 d. Saha et al.
(1992) reported that hatchability of Khaki Campbell duck eggs was greatest in eggs
stored for 3 d compared to 7 d pre-incubation.
It is advisable not to store eggs for more than two weeks, as hatchability decreases
signicantly after 14 d. Researcher have shown that storage period is related to both early
and late embryonic deaths (Onbaşılar et al., 2007). The hatchability of total and fertile
eggs decreased with increasing storage period, since early and late embryonic death was
higher due to loss of water and degradation of albumin during storage.
However, the optimal storage period is not xed. It varies according to the age of the
batch and the strain and species, due to the differences in the quality of the albumin.
Keeping eggs with the small end down and the large end upwards can result in more
successful hatching than when doing the opposite, perhaps because the incorrect
orientation of the head of the embryo towards the larger pole prevents correct
elimination of water. In this sense, Bauer et al. (1990) reported a 17% decrease in the
hatchability of embryos of broilers located with the small pole up. Apparently, this
happens because the embryo cannot nd the air chamber that is located in the round
pole, especially at the end of incubation (Bauer et al., 1990).
Conclusions
Success of the duck sector at small or large scale depends on a regular supply of one-day-
old chicks. The production of ducklings is inuenced by the fertility and hatchability of
the eggs, which are important economic factors representing the major components of
reproductive performance. Fertility and hatchability are most sensitive to the
environmental and genetic inuences. There are many factors related to producers,
breeders and environmental conditions during incubation that can inuence these
parameters, including managerial, nutritional and genetic factors as well as eggs
quality and incubator factors. There are different methods used to improve the
6 World's Poultry Science Journal, Vol. 75, December 2019
Fertility and hatchability in duck: M.E. Abd El-Hack et al.
https://www.cambridge.org/core/terms. https://doi.org/10.1017/S0043933919000060
Downloaded from https://www.cambridge.org/core. UC Davis, on 22 Oct 2019 at 03:51:15, subject to the Cambridge Core terms of use, available at
hatchability percentage of waterfowl eggs - cooling and periodic spraying with water are
some of the most commonly used. Dipping eggs and in ovo injection with nutrients such
as ascorbic acid and vitamin E during the incubation period is one of the tools used to
improve hatchability percentage.
References
ABD EL-HACK, M.E., ALAGAWANY, M. and NORELDIN, A.E. (2018) Managerial and nutritional trends
to mitigate heat stress risks in poultry farms, in: The Handbook of Environmental Chemistry, pp 1-14
(Springer, Berlin, Heidelberg. Germany).
ALI, M.A., RAHAMAN, M.A., WAHID, M.A. and SINGH, T.K. (1989) The hatchability of Muscovy duck
eggs under natural and articial incubation. Bangladesh Journal Animal Science 8 (1): 13.
ALONSO-ALVAREZ,C. (2006) Manipulation of primary sex-ratio: an updated review. Avian and Poultry
Biology Reviews 17 (1): 1-20.
APPLEGATE, T.J., HARPER, D. and LILBURN, M.S. (1998) Effect of hen production age on egg
composition and embryo development in commercial Pekin ducks. Poultry Science 77 (11): 1608-1612.
ARCHER, G.S., JEFFREY, D. and TUCKER, Z. (2017) Effect of the combination of white and red LED
lighting during incubation on layer, broiler, and Pekin duck hatchability. Poultry Science 96 (8): 2670-2675.
AWAD, A.L. (2013) Field study on hatching traits of duck eggs under Egyptian environmental conditions.
Egyptian Poultry Science Journal 33: 849-863.
BANERJEE, S. (2013) Morphological traits of duck and geese breeds of West Bengal, India. Animal Genetic
Resources/Resources Génétiques Animales/Recursos Genéticos Animales 52: 1-16.
BAUER, F., TULLETT, S.G. and WILSON, H.R. (1990) Effects of setting eggs small end up on hatchability
and posthatching performance of broilers. British Poultry Science 31 (4): 715-724.
BEAUMONT, C., MILLET, N., LE BIHAN-DUVAL, E., KIPI, A. and DUPUY, V. (1997) Genetic
parameters of survival to the different stages of embryonic death in laying hens. Poultry Science 76 (9):
1193-1196.
BENNEWITZ, J., MORGADES, O., PREISINGER, R., THALLER, G. and KALM, E. (2007) Variance
component and breeding value estimation for reproductive traits in laying hens using a Bayesian threshold
model. Poultry Science 86 (5): 823-828.
BENTON, C.E. and BRAKE, J. (1994) The effect of the presence of an embryo on albumen height and pH
during preincubation storage and incubation. Poultry Science 73 (Suppl 1): 38.
BRILLARD, J.P. (2003) Practical aspects of fertility in poultry. World's Poultry Science Journal 59 (4): 441-
446.
BROMMER, J.E. and RATTISTE, K. (2008) Hiddenreproductive conict between mates in a wild bird
population. Evolution: International Journal of Organic Evolution 62 (9): 2326-2333.
BUHR, R.J. (1995) Incubation relative humidity effects on allantoic uid volume and hatchability. Poultry
Science 74 (5): 874-884.
CHENG, Y.S., ROUVIER, R., POIVEY, J.P., TAI, J.J.L., TAI, C. and HUANG, S.C. (2002) Selection
responses for the number of fertile eggs of the Brown Tsaiya duck (Anas platyrhynchos) after a single
articial insemination with pooled Muscovy (Cairina moschata) semen. Genetics Selection Evolution 34 (5):
597.
CHOWDHURY, M.M.I., ASHRAF, A., MONDAL, S.P., MONDOL, N.M.A.A.M. and HASAN, M.M.
(2004) Effect of season on the hatchability of duck eggs. International Journal of Poultry Science 3 (6): 419-
421.
DEMIREL, S. and KIRIKÇI, K. (2009) Effect of different egg storage times on some egg quality
characteristics and hatchability of pheasants (Phasianus colchicus). Poultry Science 88 (2): 440-444.
DROUILHET, L., BASSO, B., BERNADET, M.D., CORNUEZ, A., BODIN, L., DAVID, I. and MARIE-
ETANCELIN, C. (2014) Improving residual feed intake of mule progeny of Muscovy ducks: genetic
parameters and responses to selection with emphasis on carcass composition and fatty liver quality.
Journal of Animal Science 92 (10): 4287-4296.
ELIBOL, O., PEAK, S.D. and BRAKE, J. (2002) Effect of ock age, length of egg storage, and frequency of
turning during storage on hatchability of broiler hatching eggs. Poultry Science 81 (7): 945-950.
EL-KHOLY, M.S., IBRAHIM, Z.A., EL-MEKKAWY, M.M. and ALAGAWANY, M. (2019) Inuence of
in-ovo administration of some water-soluble vitamins on hatchability traits, growth, carcass traits and blood
chemistry of Japanese quails. Annals of Animal Science 19: 97-111.
ERICSON, P.G., QU, Y., BLOM, M.P., JOHANSSON, U.S. and IRESTEDT, M. (2017) A genomic
perspective of the pink-headed duck Rhodonessa caryophyllacea suggests a long history of low effective
population size. Scientic Reports 7 (1): 16853.
World's Poultry Science Journal, Vol. 75, December 2019 7
Fertility and hatchability in duck: M.E. Abd El-Hack et al.
https://www.cambridge.org/core/terms. https://doi.org/10.1017/S0043933919000060
Downloaded from https://www.cambridge.org/core. UC Davis, on 22 Oct 2019 at 03:51:15, subject to the Cambridge Core terms of use, available at
FARGHLY, M.F.A., ABD EL-HACK, M.E., ALAGAWANY, M., SAADELDIN, I.M. and SWELUM, A.
A. (2018a) Ameliorating deleterious effects of heat stress on growing Muscovy ducklings using feed
withdrawal and cold water. Poultry Science 98: 251-259.
FARGHLY, M.F.A., ABD EL-HACK, M.E., ALAGAWANY, M., SAADELDIN, I.M. and SWELUM, A.
A. (2018b) Wet feed and cold water as heat stress modulators in growing Muscovy ducklings. Poultry
Science 97: 1588-1594.
GIRI, S.C., KUMAR, P., JAISWARA, R., BAIS, R.K.S., SAHOO, S.K., SASTRY, K.V.H. and SARAN, S.
(2014) Ideal mating sex ratio in duck houses for optimum production of fertile eggs. Indian Journal of
Poultry Science 49 (1): 106-107.
HESTER, P.Y. (2017) Effects of temperature and storage conditions on eggs, in: Egg innovations and
strategies for improvements, Section III Food Safety, Chapter 12, pp. 125-134.
IDAHOR, K.O., AKINOLA, L.A.F. and CHIA, S.S. (2015) Egg colour, weight and shape: possible indices in
the predetermination of duckling sex. Journal of Recent Advances in Agriculture 3 (1): 337-344.
JIBRIN, M.M., IDIKE, F.I., AHMAD, K. and IBRAHIM, U. (2011) Modelling incubation temperature: the
effects of incubator design, embryonic development and egg size. Journal of Agricultural Engineering and
Technology 19 (1): 46-59.
KING'ORI, A.M. (2011) Review of the factors that inuence egg fertility and hatchability in poultry.
International Journal of Poultry Science 10 (6): 483-492.
KUURMAN, W.W., BAILEY, B.A., KOOPS, W.J. and GROSSMAN, M. (2003) A model for failure of a
chicken embryo to survive incubation. Poultry Science 82 (2): 214-222.
LI, X., WEN, Y., ZHANG, J., LIU, L., JIN, L., YAN, T. and WANG, Y. (2018) The effect of low-
temperature event on the survival and growth of Juglans mandshurica seedlings within forest gaps.
Journal of Forestry Research 29 (4): 943-951.
LIPTOI, K. and HIDAS, A. (2006) Investigation of possible genetic background of early embryonic mortality
in poultry. World's Poultry Science Journal 62 (2): 326-337.
MARTÍNEZ, Y., GUERRA, L.D., RODRÍGUEZ, R. and BETANCUR, C.A. (2014) Effect of pre-
incubation storage conditions on embryonic development and chick quality of Camperos breeders.
International Journal of Animal and Veterinary Advances 6 (3): 108-111.
MOHAN, J., SHARMA, S., KOLLURI, G. and DHAMA, K. (2018) History of articial insemination in
poultry, its components and signicance. World's Poultry Science Journal 74 (3): 1-14.
NARUSHIN, V.A. and ROMANOV, M.N. (2002) Egg physical characteristics and hatchability. World's
Poultry Science Journal 58 (3): 297-303.
NICKOLOVA, M. (2005) Effect of the sex ratio on the egg fertility of Muscovy duck (Cairina moshcata).
Journal of Central European Agriculture 5 (4): 367-372.
OJEWOLA, F.E.G. (2006) Effect of Management Systems on Semen Quality of Muscovy Drakes.
International Journal of Poultry Science 5 (5): 482-484.
ONASANYA, G.O. and IKEOBI, C.O.N. (2013) Egg physical traits, performance, fertility and hatchability in
exotic and Nigerian indigenous chickens. Standard Research Journal of Agricultural Sciences 1 (1): 1-8.
ONBAŞILAR, E., ERDEM, E., HACAN, Ö. and YALÇIN, S. (2014) Effects of breeder age on mineral
contents and weight of yolk sac, embryo development, and hatchability in Pekin ducks. Poultry Science 93
(2): 473-478.
ONBAŞILAR, E., POYRAZ, Ö. and ERDEM, E. (2007) Effects of egg storage period on hatching egg
quality, hatchability, chick quality and relative growth in Pekin ducks. Archiv für Geügelkunde 71 (4): 187-
191.
PEEBLES, E.D., DOYLE, S.M., ZUMWALT, C.D., GERARD, P.D., LATOUR, M.A., BOYLE, C.R. and
SMITH, T.W. (2001) Breeder age inuences embryogenesis in broiler hatching eggs. Poultry Science 80 (3):
272-277.
PENFOLD, L.M., WILDT, D.E., HERZOG, T.L., LYNCH, W., WARE, L., DERRICKSON, S.E. and
MONFORT, S.L. (2000) Seasonal patterns of LH, testosterone and semen quality in the Northern pintail
duck (Anas acuta). Reproduction, Fertility and Development 12 (4): 229-235.
RAMLI, M.B., WAHAB, M.S., ZAIN, B.A., RAUS, A.A., RAJA, P. and PAHAT, B. (2017) Effect of
incubation temperature on ikta's quail breed with new rolling mechanism system. Journal of Mechanical
Engineering SI 4 (3): 78-88.
RANDEL, R.D., CHASE, C.C. (Jr) and WYSE, S.J. (1992) Effects of gossypol and cottonseed products on
reproduction of mammals. Journal of Animal Science 70 (5): 1628-1638.
RASHID, M., KAWSAR, M., MIAH, M. and HOWLIDER, M. (2009) Fertility and hatchability of Pekin
and Muscovy duck eggs and performance of their ducklings. Progressive Agriculture 20 (1-2): 93-98.
REYNA, K.S. and BURGGREN, W.W. (2017) Altered embryonic development in northern bobwhite quail
(Colinus virginianus) induced by pre-incubation oscillatory thermal stresses mimicking global warming
predictions. PloS One 12 (9): e0184670.
8 World's Poultry Science Journal, Vol. 75, December 2019
Fertility and hatchability in duck: M.E. Abd El-Hack et al.
https://www.cambridge.org/core/terms. https://doi.org/10.1017/S0043933919000060
Downloaded from https://www.cambridge.org/core. UC Davis, on 22 Oct 2019 at 03:51:15, subject to the Cambridge Core terms of use, available at
SAEED, M., BABAZADEH, D., NAVEED, M., ALAGAWANY, M., ABD EL-HACK, M.E., ARAIN, M.
A., TIWARI, R., SACHAN, S., KARTHIK, K., DHAMA, K., ELNESR, S.S. and CHAO, S. (2019) In
ovo delivery of various biological supplements, vaccines and drugs in poultry: current knowledge. Journal of
Science of Food and Agriculture 99: 3727-3739.
SAHA, S.K., CHOWDHURY, S.D. and HAMID, M.A. (1992) A study on the incubation of indigenous
(Desi), Khaki Campbell and crossbred (Indian Runner x Khaki Campbell, F1) duck eggs under two pre-
incubation holding periods. Asian-Australasian Journal of Animal Sciences 5 (3): 541.
TAPLAH JR, A.J., SUMINISTRADO, D.C., AMONGO, R.M.C., PARAS, F.O. (Jr), ELAURIA, J.C. and
TORKPAH, D.P. (2018) Economic analysis of duck eggs incubation using hot spring as heat source. Journal
of Development and Agricultural Economics 10 (2): 38-44.
TORO, D.M., AGUILAR, Y.M., BERTOT, R.R., HURTADO, C.B. and NAVA, O.R. (2015) Effect of
dietary supplementation with Morinda citrifolia on productivity and egg quality of laying hens. Revista
Ciencia y Agricultura 12 (2): 7-12.
UNI, Z., YADGARY, L. and YAIR, R. (2012) Nutritional limitations during poultry embryonic development.
Journal of Applied Poultry Research 21 (1): 175-184.
WAEHNER, M., PINGEL, H. and HAIDONG, S. (2015) Effect of prolonged storage of eggs of Pekin ducks
with periodical warming on internal egg quality and hatchability. Proceedings of the 4th International
Congress on New Perspectives and Challenges of Sustainable Livestock Production, October 7-9, 2015,
Belgrade, Serbia, pp: 140-144.
WEIS, J., HRNČÁR, C., PÁL, G., BARAŇSKA, B., BUJKO, J. and MALÍKOVÁ, L. (2011) Effect of the
egg size on egg loses and hatchability of the Muscovy duck. Scientic Papers Animal Science and
Biotechnologies 44 (1): 354-356.
WIDIYANINGRUM, P., LISDIANA, L. and UTAMI, N. (2016) Egg production and hatchability of local
ducks under semi intensive vs extensive managements. Journal of the Indonesian Tropical Animal
Agriculture 41 (2): 77-82.
WILSON, H.R. (1991) Interrelationships of egg size, chick size, post hatching growth and hatchability. World's
Poultry Science Journal 47 (1): 5-20.
YAIR, R. and UNI, Z. (2011) Content and uptake of minerals in the yolk of broiler embryos during incubation
and effect of nutrient enrichment. Poultry Science 90 (7): 1523-1531.
YAKUBU, A. (2013) Characterization of the local Muscovy duck in Nigeria and its potential for egg and meat
production. World's Poultry Science Journal 69 (4): 931-938.
YAKUBU, A., MUHAMMED, M.M., ARI, M.M., MUSA-AZARA, I.S. and OMEJE, J.N. (2015)
Correlation and path coefcient analysis of body weight and morphometric traits of two exotic genetic
groups of ducks in Nigeria. Bangladesh Journal of Animal Science 44 (1): 1-9.
World's Poultry Science Journal, Vol. 75, December 2019 9
Fertility and hatchability in duck: M.E. Abd El-Hack et al.
https://www.cambridge.org/core/terms. https://doi.org/10.1017/S0043933919000060
Downloaded from https://www.cambridge.org/core. UC Davis, on 22 Oct 2019 at 03:51:15, subject to the Cambridge Core terms of use, available at
... Sometimes, it may lead to morphological abnormalities of the embryo (Arora and Kosin 1966) and poor Fig. 9.7 Mist machine/ fogger quality ducklings. Prolonged storage period decreases hatchability with increased early and late embryonic deaths; mainly due to moisture loss and albumin degradation in eggs during storage (El-hack et al. 2019a). The longer period of storage also increases the spread of time over which hatching take place, reduces total hatchability and overall quality of chicks (Decuypere et al. 2001). ...
... Both genetic and non-genetic factors affect fertility and hatchability. The non-genetic factors include management of breeder (age, season, feed, etc.), egg quality, incubation conditions, etc. (El-hack et al. 2019a) ...
... The age of the breeding flock also affects the hatchability. As the age advances, the external as well as internal quality of eggs are reduced (El-hack et al. 2019a). The ratio between yolk and albumin decreased with increasing age of the birds (Peebles et al. 2001). ...
Chapter
Asia contributes significantly to world’s duck population. Asian countries like China, Vietnam, Indonesia, Malaysia, and Bangladesh have a high number of ducks. Cambodia is the duck predominant country with a share of 40.5% ducks in total poultry, while Bangladesh is the most duck dense country in the world with 438.8 ducks per square kilometer area. The world duck population increased by sixfold from 193.4 million heads in 1961 to 1177.4 million heads in 2019. The growth curve has three phases: a slow and steady early growth from 1961 to 1985 with annual growth rate (AGR) of 5.0%, a fast growth phase from 1985 to 2010 (AGR = 7.3%), and a stationary phase from 2010 onwards with AGR of −0.17%. The first human death due to avian influenza (AI) in Hong Kong in 1997, reemergence of highly pathogenic avian influenza (HPAI) in 2003 and spreading to new territories in 2007 caused significant slumps in duck production. France ranks second in duck meat production after China, although it holds seventh position in duck population. Nearly 80% of the down and feathers are produced in China. Out of the total 195.6 million kilos of duck meat exported in 2019, 71% emanated from Europe. The per capita availability of duck meat was high in European countries like Hungary (9570 g) and France (3460 g). Apart, Europe is the major exporter of live birds, with France alone contributing more than half. During the recent 5 years, the reduction of human cases of AI has signaled the revival of duck farming. Location-specific technological interventions are to be carried out to refine the existing practices and to sustain duck farming.
Chapter
Hatching egg production as well as its incubation are specialized enterprises, which need utmost care and attention. At the time a fertile egg is laid, there is already a small embryo floating on the yolk. The vitality of this embryo must be preserved during storage until the incubation process starts. To achieve this, the eggs have to be handled carefully. Specific management procedures also help to minimize the loss of hatchability during extended egg storage. Fertility and hatchability are affected by factors such as breeder management, egg quality, egg storage and incubation conditions. Production of fertile eggs, proper handling and accurate incubation process are the key factors in the production of good quality ducklings. In this chapter, the production of hatching eggs, their selection and storage conditions are discussed. The physical requirements for incubation and the various hatchery operations including candling, fumigation, hatch day activities, disinfection and waste management are dealt in this chapter. Embryonic mortality, the common symptoms shown during hatching, its causes and corrective measures, and the various factors affecting fertility and hatchability are also explained in this chapter.KeywordsHatching eggsArtificial inseminationIncubationFertilityHatchabilityHatchery hygiene
Article
Full-text available
A total of 450 fertile Japanese quail eggs were used to determine the impacts of in ovo administration of water-soluble vitamins (C, B 6 and B 12 ) on the growth performance, carcass traits, hematological and biochemical blood parameters as well as the immune response of Japanese quails. On the 7 th day of incubation, the eggs were allocated to five groups: un-injected, 0.1 ml/egg saline, 1 mg/egg vitamin C, 150 µg/egg vitamin B 6 and 20 µg/egg vitamin B 12 . The percentage of early embryonic mortality was increased (P≤0.001) in all treated groups versus the control group. Chicks that hatched from eggs injected with 1 mg/egg vitamin C exhibited a significantly greater (P≤0.05) live body weight (LBW) than those only control and saline group. During 0-2 weeks of age, the chicks hatched from eggs injected with vitamins displayed better feed conversion than the positive or negative controls. In ovo injection of vitamins had no significant effect on all carcass traits. In ovo injection with vitamins C, B 6 and B 12 increased plasma total protein and its fractions compared with the control. Plasma levels of total lipids and cholesterol were decreased in chicks hatched from eggs injected with 1 mg/egg vitamin C, 150 µg/egg vitamin B 6 or 20 µg/egg vitamin B 12 compared with those hatched from control eggs. Plasma T 3 and T 4 were increased in chicks hatched from eggs injected with vitamin C, vitamin B 6 and vitamin B 12 . The relative weights of the bursa of Fabricius and thymus were significantly (P=0.002 or 0.003) increased in the birds hatched from eggs injected with vitamins compared with those in the control or saline group. Thus, inovo injection of vitamins C, B 6 and B 12 improve and as well as the blood profile and immune response of Japanese quail.
Article
Full-text available
We studied the effect of feed withdrawal and cold water on the growth performance and health status of 180 Muscovy ducklings (28 days old) during the summer season. The experiment used a 3 × 2 factorial design consisting of 3 and 2 feeding and water systems, respectively. The birds were divided into 6 experimental groups of 30 birds each (10/replicate). The 3 feeding systems were ad libitum, full-feeding (AD); afternoon, feed withdrawn from 8 am to 2 pm daily (AF); and diurnal, feed withdrawn from 2 pm to 8 am daily (DI). The 2 water systems were tap water (TW) or cold water (CW). The results indicated that the different feeding systems with cold water positively affected the growth performance, dressed carcass, liver, gizzard, meat tenderness, juiciness, susceptibility, body temperature, tonic immobility, and blood biochemistry (glucose, aspartate aminotransferase, alanine aminotransferase, total antioxidant capacity, and malondialdehyde) of Muscovy ducklings. However, no differences in percentages of plumage, leg problems, breast blister scores, and most blood parameters were found among all groups. In conclusion, AF feeding of ducklings in combination with CW during hot conditions was more suitable than other feeding methods.
Article
Full-text available
Artificial insemination (AI) technology use in poultry production has enabled the rapid dissemination of genetic material from a small number of superior males to a high number of females. Excellent fertility in poultry can be obtained by AI compared to natural mating. Successful application of this technique needs good quality semen that should be inseminated very close to the sperm storage tubules in the female to obtain the optimum fertility in chicken. Since the 1950s, AI has been used in commercial poultry production, initially in Israel and Australia, followed by the USA. Doses of spermatozoa required for AI increases with storage time or that obtained from aged bird. The average volume of semen is between 0.05-0.50 ml in light chicken breeds and 0.1-0.9 ml in heavy males. In light turkeys, volume is 0.08-0.30 ml, whereas in heavy-weight males it is 0.1-0.33 ml. Quality evaluation of semen gives an indication of the male reproductive potential and is the major determinant of fertility and subsequently hatchability of eggs. Semen from cockerels contains between 3-7 billion sperm cells/ml. Among the several factors that influence the semen quality, sperm motility is a primary determinant of fertility in domestic fowls; however, visual examination of semen cannot be ignored for successful AI under field conditions. Dilution of low and viscous volume of avian semen is essential for handling and storage, and chicken semen typically requires a two to three-fold dilution. Collected samples should be preserved at 2-8°C for avian species, ideally with turkey sperm stored at 4-8°C, and chicken semen at 7-8°C for good fertility. Currently, the technique of AI in most of the poultry species is well developed; however, there is a need for successful development programme of this technique in non-domesticated birds to assist in creating viable, self-sustaining populations of critically endangered species.
Article
Full-text available
Successful of hatching rates in incubation quails IKTA(Institut Kemahiran Ternakan Ayam) may differ between each hatchery. There is numerous factor that influence embryonic development, among the parameter is temperature, humidity, air movement, eggs placement etc., This factor may lead to high percentage of embryo hatching and healthy DOQ (day one quail). Nine incubations were performed with 3 set of different temperature to examine the effect of different setting temperature. For eggs placement, eggs were turns using rolling mechanism 360° for every hour. Eggs obtained from local breeder with same age broiler flocks and stored for 1 to 4 days prior to intimate other commercial ideal condition. All in and all out system was used in all incubation set, eggs were place 40 piece in tray from day one until day 17. Overall it was determined that the best setting temperature is 37°c 14day then 38°c 3day that can produce average 89.17% hatching, average first hatch is in the end of day 15 complete hatch in 16 day. Temperature set 38°c 14day, then 39°c3day is 84.17%, average first hatch is day 15.5 end 16 day, not harmful compared to 39°c14day, then 40°c3day with 76.67% hatching with average first hatch is day 15.5 end 16 day. With increasing setting temperature, up to 39°c to 40°c still not successful as 37°c to 38°c, excessive temperature did not affect hatchability neither drastically speed up the hatching days, but can cause detrimental effect, embryonic mortality to eggs development. First hatch in the end of day 14, average in day 15, complete hatching in the end of day 16 , this is faster than other incubator in the market that average 17 day/ cycle. This new faster cycle cause by the consistent heat flow and humidity inside incubation chamber surrounding the eggs shell. In conclusion, ideal setting temperature 37°c 14day 38°c 3day is the best setting temperature to incubate IKTA species quails, with the efficiency of machine supply consistence temperature, humidity and eggs movement are the main parameter to ensure high hatching rates of IKTA quails.
Article
Full-text available
In an attempt to alleviate the deleterious effects of high summer temperatures, the present study investigated the effects of wet feed and cold water on the growth performance, carcass and meat quality, leg problems, physiological responses, and blood parameters of growing Muscovy ducklings. A total of 180 4-week-old ducklings were randomly divided into six experimental groups in a 3×2 factorial design that included three feed systems (AD: ad libitum dry; DW: diurnal wet; AW: ad libitum wet) and two systems of water (TW: tap water; CW: cold water). Access to wet feed and cold water affected the growth performance, dressed carcass, gizzard, meat quality (tenderness, juiciness, and susceptibility), tonic immobility, body temperature, and blood parameters (albumin: globulin (A:G) ratio and levels of glucose, alanine transferase (ALT), total antioxidant capacity (T-AOC), and malondialdehyde (MDA)) of the ducklings but had no significant effect on plumage condition, shank length, keel bone length, leg problems, or breast blisters. The body weight (BW) of the DW group was 1.97 and 3.12% greater than that of the AD and AW groups, respectively, and the BWG of the DW group was 6.91 and 10.72% greater than that of the AD and AW groups, respectively. Therefore, providing access to wet feed and cold water is highly recommended when raising Muscovy ducks in open houses under high-temperature conditions.
Article
Full-text available
The first molecular phylogenetic hypothesis for the possibly extinct pink-headed duck Rhodonessa caryophyllacea unambiguously shows that it belongs to the pochard radiation that also includes the genera Aythya and Netta. It is the sister to all modern-day pochards and belongs to a lineage that branched off from the others more than 2.8 million years ago. Rhodonessa caryophyllacea is believed to never have been common in modern time and we show this has probably been the situation for as long as 100,000 years. Our results suggest that their effective population size varied between 15,000 and 25,000 individuals during the last 150,000 years of the Pleistocene. The reasons behind this are largely unknown as very little is known about the life-history and biology of this species. Presumably it is due to factors related to feeding or to breeding, but we may never know this for sure.
Article
The technique of delivering various nutrients, supplements, immunostimulants, vaccines, and drugs via in ovo route is gaining wide attention among researchers worldwide for boosting production performance, immunity and safeguarding the health of poultry. It involves direct administration of the nutrients and biologics into poultry eggs during the incubation period and before the chicks hatch out. In ovo delivery of nutrients has been found to be more effective than post‐hatch administration in poultry production. The supplementation of feed additives, nutrients, hormones, probiotics, prebiotics or their combination via in ovo techniques has shown diverse advantages on poultry products such as improved growth performance and feed conversion efficiency, optimum development of the gastrointestinal tract, enhancing carcass yield, decreased embryo mortality and enhanced immunity of poultry. In ovo delivery of vaccination has yielded a better response against various poultry pathogens than vaccination after hatch. So, this review has aimed to provide an insight on in ovo technology and its potential applications in poultry production to deliver different nutrients, supplements, beneficial microbes, vaccines, and drugs directly into the developing embryo to achieve an improvement in post‐hatch growth, immunity and health of poultry.
Chapter
Over the past years, developing genotypes of poultry is mainly driven objecting the best productive performance at optimal environmental conditions. Since recent elevation in extreme heat wave events and increased sensitivity of the modern genotypes of poultry to heat burden became an essential concern, heat burden led to remarkable economic losses in the poultry industry, particularly in arid (hot and dry over the year) and tropical (hot and wet over the year) regions in the world. Heat stress has been reported to cause marked adverse effects on poultry reproductive and productive performances. Many investigations have studied the harmful influences of heat burden on productivity and welfare of birds. The deleterious effects of heat stress on various species of poultry range from depressed body weight, the rate of growth, feed consumption, feed conversion ratio, egg yield, and egg weight to the impaired quality of egg and meat. Moreover, the deleterious impacts of heat burden on welfare and reproduction of birds have recently attracted increasing public awareness and concern. The earlier intervention strategies involving the nutritional additions and environmental management haven’t been consistent in poultry for mitigating heat stress. So, there is a scope for exploring innovative approaches, involving the application of molecular techniques in poultry breeding to enhance poultry productivity in a sustainable manner as well as a genetic marker-assisted selection of poultry breeds for elevated heat tolerance. Subsequently, keeping in view the current situation, it is important to well understand the different molecular and cellular mechanisms included in poultry production. These mechanisms are like immunological and physiological aspects of poultry birds exposed to heat stress.
Article
In forest ecosystems, gap formation changes the allocation of abiotic resources and thus affects the survival and growth of understory plants. However, how tree seedling survival and growth respond to low-temperature events and the influencing mechanisms remain unclear. To clarify how low-temperature event limits the survival and growth of tree seedlings in the montane regions of eastern Liaoning Province, northeast China, we investigated temperature and light intensity within secondary forest gaps, and the survival and growth of Juglans mandshurica seedlings after a low-temperature event in the spring of 2014. Damage to seedlings due to low temperature significantly varied in different aspects. Seedlings in gaps on southeast-facing slopes were the most seriously damaged, followed by those in gaps on northeast-facing slopes. In contrast, seedlings in west-facing gaps and in control plots without slope aspect were not damaged. The freezing injury index for seedlings was negatively correlated with minimum temperature (r = − 0.608, P < 0.01), but it was positively correlated with light intensity (r = 0.818, P < 0.01). In addition, height and root collar diameter of damaged seedlings were significantly lower than those of the undamaged seedlings (P < 0.01) during the early growing season (April–July), but no significant difference were observed during the late growing season (July–October) (P > 0.05). The extent of seedling damage was directly related to slope aspect. Low temperature and high light intensity were found to be the dominant factors affecting extent of damage to seedlings on southeast- and northeast-facing slopes.