Biology of stress in poultry with emphasis on glucocorticoids and the
heterophil to lymphocyte ratio
Colin G. Scanes1
Department of Biological Sciences, University of Wisconsin Milwaukee, Milwaukee, WI 53211 USA
ABSTRACT
The biology of stress in chickens is
reviewed. Not only is stress associated with depressed production, but animal welfare influences
consumer acceptance of poultry and eggs. The
reciprocal of well-being is stress. The hypothalamopituitary-adrenocortical axis in poultry consists of the
neuropeptides, corticotropin releasing hormone, and
arginine vasotocin that are released from the median eminence; the polypeptide hormone, adrenocorticotropic hormone (ACTH) secreted by the anterior
pituitary gland; and the glucocorticoid hormone, corticosterone (CORT), synthesized by the adrenocortical cells. Many, but not all, stresses in chickens
increase circulating concentrations of CORT. Circulating concentrations levels of CORT (both basal and in
response to stressors) show marked differences in the
literature, suggesting further attention is needed to ensure assays are validated for CORT in chicken plasma
and other sources - excreta and feathers. As glucocorticoids influence the heterophil:lymphocyte (H:L)
ratio, it is not surprising that the H:L is shifted
with stress. It is recommended that close attention
needs to be placed on the validity of assays including cross-laboratory standards. In addition, there is
a strong case for determining multiple parameters of
stress.
Key words: stress, corticosterone, heterophil:lymphocyte ratio, leukocyte, erythrocyte
2016 Poultry Science 95:2208–2215
http://dx.doi.org/10.3382/ps/pew137
INTRODUCTION
A major contribution to policy on animal welfare was
a report to the United Kingdom government (Bramwell,
1965). The report consisted of five freedoms: 1. freedom
from hunger, malnutrition and thirst, 2. freedom from
discomfort (including the provision of shelter from inclement weather), 3. freedom from disease or injury or
pain, 4. freedom from fear or distress or mental discomfort, and 5. freedom to express all natural behaviors.
Veissier and Boissy (2007) noted “concepts of welfare
and stress may be considered as opposites since welfare
cannot be achieved under stress and vice versa”. Wellbeing is the absence of stress or a low level of stress
(summarized below).
Well − being = A/Stress
Stress = B x Integrated plasma concentrations of
corticosterone over time together with the
integrals of other stress parameters over time
(2)
Where B is a constant.
STRESS AND CORTICOSTERONE
(1)
where A is a constant.
Hans Selye (1936) advanced the physiological model
of stress – the “General Adaptation Syndrome”. This
was extended to stress evokes increased secretion of glucocorticoid hormones from the adrenal cortex (see equation 2) (Sapolsky et al., 2000). In poultry, two of the
C 2016 Poultry Science Association Inc.
Received September 30, 2015.
Accepted March 16, 2016.
1
Corresponding author: [email protected]
most common physiological parameters of stress are circulating concentrations of the adreno-cortical hormone,
corticosterone (CORT) and the heterophil:lymphocyte
ratio (H:L). These are discussed in more detail in the
subsequent sections.
The hypothalamo-pituitary-adrenocortical axis in
chickens is summarized in figure 1. In poultry, the major avian adrenal glucocorticoid is CORT. Some cortisol
is produced, albeit at a very low level (Kalliecharan and
Hall, 1974; reviewed: Carsia, 2015). Plasma concentrations of CORT are elevated by stressors due to increased
secretion of adrenocorticotropic hormone (ACTH) and
corticotropin releasing hormone. Cortical cell number
and function can also be affected by the stress of dietary protein restriction (Carsia et al., 1988). Table 1
summarizes the effects of stressors on circulating concentrations of CORT in chickens. There are increases in
2208
BIOLOGY OF STRESS IN POULTRY
2209
Table 1. Stressors and plasma concentrations of corticosterone in chickens.
Effect
Biological/production stressors
Cold
Heat
Acute heat stress
Diethyl ether
Stocking density
E. coli endotoxin
Cooping stress
Immobilization
Restraint
Handling
Shackling
Crating alone or with transportation
Transportation
Transportation
Ammonia
Nutritional/metabolic stressors
Fasting
Insulin induced hypoglycemia
Chronic feed restriction
Skip a day feeding regimen
Protein deprivation
Molting
Early in forced molt
Fish oil addition to feed
Re-feeding following fasting
Overnight feed withdrawal
Lighting
Light source
Light intensity
Reference
↑↑
↑↑
→
↑↑
↑
↑↑
↑↑
↑↑
↑↑
↑↑
↑↑
→
↑
↓
→
Beuving and Vonder, 1978
Beuving and Vonder, 1978
Xie et al., 2015
Scanes et al., 1980
Mirfendereski and Jahanian, 2015
Curtis et al., 1980; Scanes et al., 1980
Satterlee et al., 1994
Beuving and Vonder, 1978; Kang and Kuenzel, 2014
Fallahsharoudi et al., 2015
Kannan et al., 1997a
Kannan et al., 1997a; Bedánová et al., 2007; Huang et al., 2014
Kannan et al., 1997b; Zhang et al., 2009
Al-Aqil et al., 2013
Vosmerova et al., 2010
Olanrewaju et al., 2008
↑↑
↑↑
↑↑
↑↑
↑↑
↑↑
↓
↓
↓↓
↓
Harvey et al., 1983
Scanes et al., 1980
de Jong et al., 2002; Najafi et al., 2015; Pál et al., 2015
de Beer et al., 2008
Carsia et al., 1988
Davis et al., 2000
Gildersleeve et al., 1982
Pál et al., 2015
Harvey et al., 1983
Kannan et al., 1997a,b
↑
→
Huth and Archer, 2015
Olanrewaju et al., 2014
circulating concentrations of CORT in response to the
following stressors:
r Biological/production stressors such as heat, cold,
stocking density, restraint, cooping, and shackling.
r Nutritional stressors including fasting, feed restric-
tion, and dietary protein deficiency.
r Parallelism for diluted samples with a standard
curve.
r Recovery (determining CORT when added to
plasma and stripped plasma).
r Accuracy/reliability/precision.
r If used, extraction efficiency.
r The extent to which the assay detects total or free
CORT.
r Papers should include results from a series of stan-
However, some apparently noxious stimuli are without effect (e.g., ammonia - Olanrewaju et al., 2008)
and some apparently benign factors (e.g., light source)
influence circulating concentrations of CORT (Huth
and Archer, 2015). The available evidence for effects of
transportation are contradictory (Table 1) and require
further investigation. While circulating concentrations
of CORT are undoubtedly very useful, it is questioned
whether are always a reliable indicator of stress.
It is questioned whether the techniques employed have been adequately validated for chicken
plasma/serum. For instance, plasma concentrations of
CORT in unstressed chickens vary over two orders of
magnitude (Table 2). Similarly, plasma concentrations
in stressed chickens range from 0.25 ng mL−1 (Kang
and Kuenzel, 2014) and ∼150 ng mL−1 (Huang et al.,
2014). Criteria to be followed include the following:
r Specificity for CORT or cortisol assays (includ-
ing cross-reactivities with other glucocorticoids and
their metabolites).
dards (a low and a high CORT samples of chicken
plasma). These standards need to be available internationally.
In addition, it is strongly recommended that papers examining effects of stressors also include data on
plasma concentrations of CORT in basal or unstressed
conditions from the same age and population of chickens. There are other problems. Despite abundant earlier
evidence that cortisol is only present at very low levels in chickens, Kim and colleagues (2015) recently reported high plasma concentrations of cortisol. The basis
for this is not readily apparent but again points to the
need for close attention to assay validity. Moreover, it
has been reported that chicken excreta has a concentration of an unspecified corticosterone metabolite of
140 ng g−1 as determined by ELISA (Alm et al., 2014).
Again a strong case can be made to greater attention
to what is being measured.
Studies on the effect of stressors can be confounded
by changes in plasma concentrations of CORT based on
2210
SCANES
Table 2. Differences in basal concentrations of CORT in unstressed chickens across multiple studies.
CORT (ng mL-1 )
Reference
Method
Source/notes
Kang and Kuenzel, 2014
Fallahsharoudi et al., 2015
Huth and Archer, 2015
Najafi et al., 2015
Puvadolpirod and Thaxton, 2000a
Xie et al., 2015
Radio-immuno assay (RIA)
Mass spectrometry
ELISA kit
RIA kit
RIA
ELISA
Davis et al., 2000
RIA kit
DeBeer et al., 2008
Olanrewaju et al., 2014
RIA
ELISA
Satterlee et al., 1994
RIA
Vosmerova et al., 2010
ELISA
Mirfendereski and Jahanian, 2015
ELISA
Satterlee et al., 1980#
RIA
Edens and Siegel, 1975
Zhang et al., 2009
Competitive binding protein assay (CPB)
ELISA
-1
Basal (ng mL )
< 0.3
0.3 to 1.0
After extraction
Enzo Life Sciences (Farmingdale, NY)
IDS Ltd (Bolton, UK)
Cayman Chemical Company (Ann
Arbor, MI)
1 to 5
Diagnostic Products Corporation (Los
Angeles, CA)
ICN Pharmaceuticals (Costa Mesa, CA)
Diagnostic Products Corporation (Los
Angeles, CA) Standards diluted in
stripped chicken plasma
Extraction
5 to 20
> 20
circadian pattern (Wilson et al., 1984; de Jong et al.,
2001) or the ovulatory cycle (Wilson and Cunningham,
1981). CORT in avian blood is predominantly bound
to proteins; one a high affinity corticosteroid binding
protein (CBG; also known as transcortin) (Wingfield
et al., 1984) and the other, albumin, a low affinity binding high capacity binding protein. There has been little
attention to characterization of CBG or determining
changes in the circulating concentrations of CBG and
free CORT in the chicken since studies over 30 years
ago (Gould and Siegel, 1978, 1985). This is particularly
important, as it is assumed that only free CORT is biological active.
Glucocorticoids exert a number of effects in chickens,
including the following:
r Decreased growth e.g., Donker and Beuving, 1989;
r
r
r
r
r
Post et al., 2003; Song et al., 2011; Zulkifli et al.,
2014).
Increased weights of the liver, intestine and adipose
tissue (e.g., Bartov et al., 1980; Gross et al., 1980;
Hamano, 2006).
Shifts in protein, lipid and protein metabolism (discussed below).
Increased fear behaviors with elevated tonic immobility (Jones et al., 1988; El-Lethey et al., 2001)
and feather pecking (El-Lethey et al., 2001).
Depressed immune system with the H:L greatly elevated (Gross et al., 1980; Gross and Siegel, 1983;
Vicuña et al., 2015) (see section below).
Depressed gastrointestinal functioning (see section
below).
Cayman Chemical Company, Ann
Arbor, MI
Diagnostic Products Corporation (Los
Angeles, CA) Standards diluted in
stripped chicken plasma
Extraction
Diagnostic Products Corporation (Los
Angeles, CA)
Glucocorticoids and Metabolism
This section addresses the physiological effects of
glucocorticoids on metabolism albeit briefly. Exogenous glucocorticoids increase circulating concentration
of glucose in chickens (e.g., Li et al., 2009; Wang et al.,
2012a). The increases in circulating concentrations of
glucose are likely to be due to increased glucose synthesis in the liver with greater rates of hepatic gluconeogenesis reported with glucocorticoid treatment (Kobayashi
et al., 1989). In addition, the increases in circulating
concentrations of glucose are probably due to reduced
utilization of glucose; dexamethasone suppressing insulin stimulated glucose uptake by chick embryonic myoblasts (Zhao et al., 2012).
One role for CORT is exerting profound effects on
lipid metabolism. Glucocorticoids increase fat accumulation in abdominal, cervical, and thigh adipose tissue together with in the liver and skeletal muscle, e.g.,
breast muscle (Cai et al., 2009; Wang et al., 2012a,b).
A role of CORT is likely to be increasing the synthesis
of fatty acids. In fasted but not fed chickens, dexamethasone in vivo increases expression of acetyl-CoA carboxylase and fatty acid synthase in the liver (Cai et al.,
2009; 2011). In vitro, hepatic expression of acetyl-CoA
carboxylase and fatty acid synthase is increased by combined treatment with insulin and dexamethasone (Cai
et al., 2011). In addition, CORT increases uptake of
fatty acid by at least skeletal muscles. Glucocorticoids
increase the expression of fatty acid transport protein
1 and insulin receptor in the pectoralis major, a fasttwitch glycolytic fiber type muscle, and biceps femoris,
a slow-twitch oxidative fiber type muscle (Wang et al.,
BIOLOGY OF STRESS IN POULTRY
2012a,c). Despite the increase in adiposity with glucocorticoid administration, there is evidence for increased
lipolysis. In multiple studies, administration of glucocorticoid is accompanied with elevated circulating concentrations of non-esterified fatty acids and both expression and levels of triglyceride lipase in chicken adipose tissue (Serr et al., 2011).
Glucocorticoids influence protein metabolism with
decreases in protein synthesis and increases in degradation in skeletal muscle. In vivo muscle protein synthesis
is depressed by the glucocorticoid dexamethasone with
decreased phosphorylation of mTOR and ribosomal
protein S6 protein kinase (Wang et al., 2015). Glucocorticoids increase net protein degradation in skeletal muscle (Klasing et al., 1987). There are consistent increases
in the circulating concentrations of urate/uric acid with
dexamethasone administration (Song et al., 2011); reflecting increased protein/amino-acid catabolism. Glucocorticoid administration is followed by increased rates
of gluconeogenesis in the liver (Kobayashi et al., 1989).
While glucocorticoids are predominantly reported to
depress growth of skeletal muscle (e.g., Gross et al.,
1980; Wang et al., 2012b), this is not the case for all
studies (e.g., Song et al., 2011). Expression of growth related genes in skeletal muscle have been reported to be
influenced by dexamethasone administration but there
are markedly different effects between individual studies (Song et al., 2011).
The effects of CORT on chicken metabolism is due
to some direct effects but some effects mediated by the
increase in circulating concentrations of insulin (Cai
et al., 2011; Song et al., 2011; Wang et al., 2012a).
What is not clear is whether effects of either CORT
or dexamethasone on metabolism are physiological versus pharmacological. Moreover, many studies involve
daily injections with concomitant major changes in circulating concentrations during the day. It is also argued
that administration either via the feed or water is also
problematic as there are large shifts in eating/drinking
with diurnal intake and nocturnal abstinence. It is
recommended that future studies of the effects of
corticosterone in chickens employ dosages of the
endogenous hormone, CORT, rather than a synthetic
glucocorticoid, to mimic the concentrations of CORT
during stress and employ continuous administration.
Glucocorticoids and Gastro-intestinal
Functioning
There is strong evidence that glucocorticoids inhibit
gastro-intestinal functioning. Administration of the glucocorticoid, dexamethasone is followed by reductions
of the height of jejunal villi and, hence, of small intestinal absorptive area (Li et al., 2009; Chang et al.,
2015). Moreover glucocorticoids decrease absorption of
the following: glucose based on lower expression of Na+ dependent glucose transporter in jejunal mucous (Li
et al., 2009); of dipeptides based on reduced absorption
2211
of glycyl sarcosine in jejunal brush border membrane
vesicles in vitro (Chang et al., 2015) and calcium by
everted sacs of chicken small intestine (Fox and Heath,
1981). Moreover, the administration of the glucocorticoid, dexamethasone, is followed by increased permeability of intestine and in live bacteria in liver (Vicuña
et al., 2015). It is presumed that the change in permeability allows bacteria, including pathogens, through
the intestinal barrier into the blood and then be transported to organs. There are no effects of corticosterone
on the digestibility of amino-acids (Virden et al., 2007).
STRESS AND LEUKOCYTES
It is well recognized that stress evokes marked
shifts in the H:L ratio in birds (reviewed for instance:
Maxwell, 1993; Davis et al., 2008). There is increasing
interest in this parameter as an index of stress in chickens (e.g., Bedánová et al., 2006a; Prieto and Campo,
2010; Redmond et al., 2011; Al-Aqil et al., 2013; Huth
and Archer, 2015; Najafi et al., 2015) and wild birds (reviewed Davis et al., 2008). The stress induced increase
in the H:L ratio can be attributed, at least partially,
to effects of stress increasing CORT. Administration
of CORT or dexamethasone is followed by dramatic
increases in the H:L ratio (Gross et al., 1980; Gross
and Siegel, 1983; Vicuña et al., 2015). Moreover, dexamethasone has been reported to increase blood concentration of leukocytes together with decreases in the
concentrations of monocytes (Vicuña et al., 2015).
Multiple stressors increase both the H:L ratio and
circulating concentrations of CORT. The initial report
of this demonstrated that social stress is followed by
increases in both the H:L ratio and circulating concentrations of CORT in chickens (Gross and Siegel, 1983).
There have been extensive series of studies reporting
that the H:L ratio and CORT are elevated by multiple
stressors such as the following:
r
r
r
r
r
r
r
r
E.coli endotoxin challenge (Gross and Siegel, 1983).
Fasting (Gross and Siegel, 1983).
Feed restriction (Najafi et al., 2015).
Heat stress (Prieto and Campo, 2010; earlier research reviewed: Maxwell, 1993).
Lighting sources (Huth and Archer, 2015).
Salmonella typhimurium or S. enteritis challenge
(Redmond et al., 2011; earlier research reviewed:
Maxwell, 1993).
Shackling (Bedánová et al., 2006a).
Transportation stress (reviewed: Maxwell, 1993;
also see Al-Murrani et al., 1997; Al-Aqil et al.,
2013).
Similar to the situation in chickens, either transportation and dexamethasone increases both the H:L ratios
and mortality following E. Coli challenge in turkeys
(Huff et al., 2005). Most but not all of these stressors
increase both H:L ratio and circulating concentrations
of CORT. The case with transportation stress is less
2212
SCANES
Table 3. Comparison of heterophils and lymphocytes between
commercial chickens and indigenous/native chickens/randombred chickens. Data is % + (n = number of studies and populations) SEM.
Population
Heterophils
Lymphocytes
Indigenous/native chickens/
random-bred chickens
Commercial chickens
26.3 ± (11) 2.4
60.5 ± (11) 2.9
25.0 ± (8) 2.3
65.8 ± (8) 2.6
Based on Scanes and Christensen, 2014.
simple with both increases and no effects being reported
for circulating concentrations of CORT and the H:L ratio (Kannan et al., 1997b; Zhang et al., 2009). There
are cases when H:L does not mirror circulating concentrations of CORT. For instance, while high fear chickens exhibit an elevated H:L ratios compared to low fear
chickens but there was no differences in the adrenal
CORT response to ACTH (Beuving et al., 1989). Furthermore, malathion decreases the H:L ratio (Gross and
Siegel, 1983) despite the increases in adrenocortical activity (Goyal et al., 1986). There are also elevated circulating concentrations of CORT in birds treated with another cholinesterase inhibitor, parathion (Rattner et al.,
1982). These studies would suggest that H:L ratio can
be shifted in a glucocorticoid independent manner in
addition to the prevailing manner via COR.
Were commercial chickens stressed due to intensive breeding and intensive production systems, then
it would be predicted that there should be marked
changes in the differential leukocyte count with shifts in
both heterophils and lymphocytes between commercial
chickens and unselected indigenous chickens. However,
there were no such differences in the differential leukocyte count in a meta-analysis (Table 3) (Scanes and
Christensen, 2014) and no difference with the ancestral
species from which chickens were domesticated – the
red jungle fowl. This provides supportive evidence that
commercial chickens are not stressed. The utility of H:L
ratios in evaluation of stress and well-being in poultry
continues to be warranted.
STRESS AND ERYTHROCYTES
Hematocrit (HCT)/Packed Cell Volume (PCV) has
been used as an index of animal well-being. For instance, laboratory mice being used as a source of blood
are euthanized if their HCT/PCV is less than 40%
for two weeks to ensure humane treatment (Raabe
et al., 2011). Were commercial chickens stressed due
to intensive breeding and intensive production systems,
then it would be predicted that there may be differences in HCT/PCV between commercial chickens and
unselected indigenous chickens. HCT/PCV was lower
in commercial chickens than in indigenous/randombred chickens in a meta-analysis of multiple studies (Table 4) (Scanes and Christensen, 2014). Parenthetically, it is noted that HCT/PCV was lower in
indigenous/random-bred chickens than the ancestral
Table 4. Comparison of hematocrit (Hct)/packed cell volume
(PCV) between all birds, Gallinaceous birds, wild jungle fowl, indigenous/native chickens/random-bred chickens and commercial
chickens. Data is % + (n = number of studies and populations)
SEM.
Population
Hematocrit
Wild birds (Class Aves Infra-class Neognathae)
Gallinaceous birds
Jungle fowl (Gallus gallus)
Indigenous/native chickens/random-bred
chickens
Commercial chickens
Δ
44.7
39.9
40.2
32.8
±
±
±
±
(318Δ ) 0.3d
(18) 1.3c
(3) 2.1c
(16) 1.1b
29.6 ± (10) 1.5a
Based on Scanes and Christensen, 2014.
Δ
Number of species.
a–d
Different superscript letter indicate difference.
species, the red jungle fowl (Eriksson et al., 2008;
Girdland Flink et al., 2014). The mean HCT/PCV in
the meta-analysis of commercial chickens was 29.6%
(Scanes and Christensen, 2014). This is nearly identical to the situation in chickens selected for low HCT
(29.7%) (Shlosberg et al., 1996). The low HCT/PCV in
commercial chickens and its relationship to stress warrants further study.
There is evidence for stressors influencing another
hematological parameter either decreasing or increasing blood hemoglobin concentrations. On one hand,
there are decreases in circulating concentrations of
hemoglobin with the stress of shackling which also results in elevated circulating concentrations of CORT
(Bedánová et al., 2006a). However, chickens reared on
reduced floor space also have increases in blood concentration of hemoglobin (Bedánová et al., 2006b).
CONCLUSIONS
There are multiple physiological responses to stress.
It should not be assumed that only one parameter
should be measured to determine stress irrespective of
whether it is plasma concentrations of CORT or any
other hormone or the H:L ratio or a behavioral response. There is a clear need for research and perhaps
even re-examination of the concept of stress. Examples
of questions for further study include the following:
r Are concentrations of CORT determined in differ-
ent assay systems valid and do they accurately reflect the “real situation”?
r Do different stressors influence plasma concentrations of CORT, other glucocorticoids, CBG,
epinephrine (EPI), and norepinephrine (NE) together with blood H:L ratios? Are the changes consistent?
r There is a need for considerably more studies on
effects of stressors on EPI and NE in poultry.
r Are there approaches that provide an index of
chronic stress of the growth period such as integrated circulating concentrations of CORT? Possible approaches include feather CORT, adrenal
BIOLOGY OF STRESS IN POULTRY
CORT and/or expression of key steroidogenesis enzymes in the adrenal gland.
Physiological and behavioral indices of stress are very
useful as they can be quantified and broadly fit with
preconceived views of well-being. It seems that wellbeing is the inverse of stress and the aggregate of
stress quantification. It is still unclear whether these indices are definitive in demonstrating the well-being of
poultry.
REFERENCES
Al-Aqil, A., I. Zulkifli, M. Hair Bejo, A. Q. Sazili, M. A. Rajion, and
M. N. Somchit. 2013. Changes in heat shock protein 70, blood
parameters, and fear-related behavior in broiler chickens as affected by pleasant and unpleasant human contact. Poult. Sci.
92:33–40.
Alm, M., L. Holm, R. Tauson, and H. Wall. 2014. Corticosterone
metabolites in laying hen droppings-Effects of fiber enrichment,
genotype, and daily variations. Poult. Sci. 93:2615–2621.
Al-Murrani, W. K., A. Kassab, H. Z. al-Sam, and A. M. al-Athari.
1997. Heterophil/lymphocyte ratio as a selection criterion for heat
resistance in domestic fowls. Br. Poult. Sci. 38:159–163.
Bartov, I., L. S. Jensen, and J. R. Veltmann, Jr. 1980. Effect of
corticosterone and prolactin on fattening in broiler chicks. Poult.
Sci. 59:1328–1334.
Bedánová, I., E. Voslarova, P. V. Vecerek, V. Pistekova, and P.
Chloupek. 2006a. Stress in broilers resulting from shackling. Acta
Vet. Brno. 76:129–135.
Bedánová, I., E. Voslárová, V. Vecerek, V. Pistĕková, and P.
Chloupek. 2006b. Effects of reduction in floor space during crating on haematological indices in broilers. Berl. Munch. Tierarztl.
Wochenschr. 119:17–21.
Bedánová, I., E. Voslarova, P. Chloupek, V. Pistekova, P. Suchy, J.
Blahova, R. Dobsikova, and V. Vecerek. 2007. Stress in broilers
resulting from shackling. Poult. Sci. 86:1065–1069.
Beuving, G., and G. M. A. Vonder. 1978. Effect of stressing factors
on corticosterone levels in the plasma of laying hens. Gen. Comp.
Endocrinol. 35:153–159.
Beuving, G., R. B. Jones, and H. J. Blokhius. 1989. Adrenocortical and heterophil/lymphocyte responses to challenge in hens
showing short or long tonic immobility reactions. Br. Poult. Sci.
30:175–184.
Brambell, R. 1965. Report of the technical committee to enquire into
the welfare of animals kept under intensive livestock husbandry
systems. Her Majesty’s Stationary Office, London.
Cai, Y. L., Z. G. Song, X. H. Zhang, X. J. Wang, H. C. Jiao, and
H. Lin. 2009. Increased de novo lipogenesis in liver contributes to
the augmented fat deposition in dexamethasone exposed broiler
chickens (Gallus gallus domesticus). Comp. Biochem. Physiol. A.,
150:164–169.
Cai, Y., Z. Song, X. Wang, H. Jiao, and H. Lin. 2011.
Dexamethasone-induced hepatic lipogenesis is insulin dependent
in chickens (Gallus gallus domesticus). Stress. 14:273–281.
Carsia, R. V. 2015. Adrenals. Pages 577–611 in Sturkie’s Avian Physiology, 6th edition, C. G. Scanes, ed. Academic Press, New York.
Carsia, R. V., H. Weber, and T. J. Lauterio. 1988. Protein malnutrition in the domestic fowl induces alterations in adrenocortical
function. Endocrinology. 122:673–680.
Chang, W. H., J. J. Li, S. Zhang, A. J. Zheng, J. L. Yuan, H. Y. Cai,
and G. H. Liu. 2015. Effects of glucocorticoid-induced stress on
absorption of glycylsarcosine in jejunum of broilers. Poult. Sci.
94:700–705.
Curtis, M. J., I. H. Flack, and S. Harvey. 1980. The effect of Escherichia coli endotoxins on the concentrations of corticosterone
and growth hormone in the plasma of the domestic fowl. Res.
Vet. Sci. 28:123–127.
Darras, V. M., S. P. Kotanen, K. L. Geris, L. R. Berghman, and E.
R. Kühn. 1996. Plasma thyroid hormone levels and iodothyronine
2213
deiodinase activity following an acute glucocorticoid challenge in
embryonic compared with posthatch chickens. Gen. Comp. Endocrinol. 104:203–212.
Davis, G. S., K. E. Anderson, and A. S. Carroll. 2000. The effects of
long-term caging and molt of Single Comb White Leghorn hens
on heterophil to lymphocyte ratios, corticosterone and thyroid
hormones. Poult. Sci. 79:514–518.
Davis, A. K., D. L. Maney, and J. C. Maerz, 2008. The use of leukocyte profiles to measure stress in vertebrates: a review for ecologists. Funct. Ecol. 22:760–772.
de Beer, M., J. P. McMurtry, D. M. Brocht, and C. N. Coon. 2008.
An examination of the role of feeding regimens in regulating
metabolism during the broiler breeder grower period. 2. Plasma
hormones and metabolites. Poult. Sci. 87:264–275.
de Jong, I. C., A. S. van Voorst, J. H. Erkens, D. A. Ehlhardt, and
H. J. Blokhuis. 2001. Determination of the circadian rhythm in
plasma corticosterone and catecholamine concentrations in growing broiler breeders using intravenous cannulation. Physiol. Behav. 74:299–304.
de Jong, I. C., S. van Voorst, D. A. Ehlhardt, and H. J. Blokhuis.
2002. Effects of restricted feeding on physiological stress parameters in growing broiler breeders. Br. Poult. Sci. 43:157–168.
Donker, R. A., and G. Beuving. 1989. Effect of corticosterone infusion on plasma corticosterone concentration, antibody production, circulating leukocytes and growth in chicken lines selected
for humoral immune responsiveness. Br. Poult. Sci. 30:361–369.
El-Lethey, H., T. W. Jungi, and B. Huber-Eicher. 2001. Effects of
feeding corticosterone and housing conditions on feather pecking
in laying hens (Gallus gallus domesticus). Physiol. Behav. 73:243–
251
Eriksson, J., G. Larson, U. Gunnarsson, B. Bed’hom, M. TixierBoichard, L. Strömstedt, D. Wright, A. Jungerius, A. Vereijken,
E. Randi, P. Jensen, and L. Andersson. 2008. Identification of the
Yellow Skin gene reveals a hybrid origin of the domestic chicken.
PLoS Genet. 4:e1000010.
Fallahsharoudi, A., N. de Kock, M. Johnsson, S. J. Ubhayasekera, J.
Bergquist, D. Wright, and P. Jensen. 2015. Domestication effects
on stress induced steroid secretion and adrenal gene expression
in chickens. Sci. Rep. 5:15345.
Fox, J., and H. Heath, 3rd. 1981. Retarded growth rate caused by glucocorticoid treatment or dietary restriction: associated changes
duodenal, jejunal, and ileal calcium absorption in the chick. Endocrinology. 108:1138–1141.
Gildersleeve, R. P., D. G. Satterlee, W. A. Johnson, and T. R. Scott.
1982. The effects of forced molt treatment on selected steroids in
hens. Poult. Sci. 61:2362–2369.
Girdland Flink, L., R. Allen, R. Barnett, H. Malmström, J. Peters,
J. Eriksson, L. Andersson, K. Dobney, and G. Larson. 2014.
Establishing the validity of domestication genes using DNA from
ancient chickens. Proc. Natl. Acad. Sci. U.S.A. 111:6184–6189.
Gould, N. R., and H. S. Siegel. 1978. Partial purification and characterization of chicken corticosteroid-binding globulin. Poult. Sci.
57:1733–1739.
Gould, N. R., and H. S. Siegel. 1985. Effects of corticotropin and
heat on corticosteroid-binding capacity and serum corticosteroid
in White Rock chickens. Poult. Sci. 64:144–148.
Goyal, B. S., S. K. Garg, and B. D. Garg. 1986. Malathion induces
hyper-adrenal activity in WLH chicks. Current Science. 55:526–
528.
Gross, W. B., and H. S. Siegel. 1983. Evaluation of the heterophil/lymphocyte ratio as a measure of stress in chickens. Avian
Dis. 27:972–979.
Gross, W. B., P. B. Siegel, and R. T. DuBose. 1980. Some effects of
feeding corticosterone to chickens. Poult. Sci. 59:516–522.
Hamano, Y. 2006. Effects of dietary lipoic acid on plasma lipid, in
vivo insulin sensitivity, metabolic response to corticosterone and
in vitro lipolysis in broiler chickens. Br. J. Nutr. 95:1094–1101.
Harvey, S., H. Klandorf, and Y. Pinchasov. 1983. Visual and
metabolic stimuli cause adrenocortical suppression in fasted
chickens during refeeding. Neuroendocrinology. 37:59–63.
Huang, J. C., M. Huang, P. Wang, L. Zhao, X. L. Xu, G. H. Zhou,
and J. X. Sun. 2014. Effects of physical restraint and electrical
stunning on plasma corticosterone, postmortem metabolism, and
quality of broiler breast muscle. J. Anim. Sci. 92:5749–5756.
2214
Huff, G. R., W. E. Huff, J. M. Balog, N. C. Rath, N. B. Anthony,
and K. E. Nestor. 2005. Poult. Sci. 84:709–717.
Huth, J. C., and G. S. Archer. 2015. Comparison of two LED light
bulbs to a dimmable CFL and their effects on broiler chicken
growth, stress, and fear. Poult. Sci. 94:2027–2036.
Jones, R. B., G. Beuving, and H. J. Blokhuis. 1988. Tonic immobility and heterophil/lymphocyte responses of the domestic fowl to
corticosterone infusion. Physiol. Behav. 42:249–253.
Kalliecharan, R., and B. K. Hall. 1974. A developmental study of
the levels of progesterone, corticosterone, cortisol, and cortisone
circulating in plasma of chick embryos. Gen. Comp. Endocrinol.
24:364–372.
Kannan, G., J. L. Heath, C. J. Wabeck, and J. A. Mench. 1997a.
Shackling of broilers: Effects on stress responses and breast meat
quality. Br. Poult. Sci. 38:323–332.
Kannan, G., J. L. Heath, C. J. Wabeck, M. C. Souza, J. C. Howe, and
J. A. Mench. 1997b. Effects of crating and transport on stress and
meat quality characteristics in broilers. Poult. Sci. 76:523–529.
Kang, S. W., and W. J. Kuenzel. 2014. Regulation of gene expression
of vasotocin and corticotropin-releasing hormone receptors in the
avian anterior pituitary by corticosterone.
Kim, D. W., M. M. Mushtaq, R. H. K. Kang., J. H. Kim, J. C.
Na, J. Hwangbo, J. D. Kim, C. B. Yang, B. J. Park, and H. C.
Choi. 2015. Various levels and forms of dietary α-lipoic acid in
broiler chickens: Impact on blood biochemistry, stress response,
liver enzymes, and antibody titers. Poult. Sci. 94:226–231.
Klasing, K. C., D. E. Laurin, R. K. Peng, and D. M. Fry. 1987.
Immunologically mediated growth depression in chicks: influence
of feed intake, corticosterone and interleukin-1. J. Nutr. 117:1629–
1637.
Kobayashi, T., H. Iwai, R. Uchimoto, M. Ohta, M. Shiota,
and T. Sugano. 1989. Gluconeogenesis in perfused livers from
dexamethasone-treated chickens. Am. J. Physiol. 256:R907–914.
Li, Y., H. Y. Cai, G. H. Liu, X. L. Dong, W. H. Chang, S. Zhang,
A. J. Zheng, and G. L. Chen. 2009. Effects of stress simulated
by dexamethasone on jejunal glucose transport in broilers. Poult.
Sci. 88:330–337.
Maxwell, M. H. 1993. Avian blood leukocyte responses to stress.
World’s Poult. Sci. J. 49:34–43.
Mirfendereski, E., and R. Jahanian. 2015. Effects of dietary organic chromium and vitamin C supplementation on performance, immune responses, blood metabolites, and stress status
of laying hens subjected to high stocking density. Poult. Sci.
94:281–288.
Najafi, P., I. Zulkifli, A. F. Soleimani, and P. Kashiani. 2015. The
effect of different degrees of feed restriction on heat shock protein
70, acute phase proteins, and other blood parameters in female
broiler breeders. Poult. Sci. 94:2322–2329.
Olanrewaju, H. A., J. P. Thaxton, W. A. Dozier, J. Purswell, S. D.
Collier, and S. L. Branton. 2008. Interactive effects of ammonia
and light intensity on hematochemical variables in broiler chickens. Poult. Sci. 87:1407–1414.
Olanrewaju, H. A., J. L. Purswell, S. D. Collier, and S. L. Branton.
2014. Effects of genetic strain and light intensity on blood physiological variables of broilers grown to heavy weights. Poult. Sci.
93:970–978.
Pál, L., M. Kulcsár, J. Poór, L. Wágner, S. Nagy, K. Dublecz, and
F. Husvéth. 2015. Effect of feeding different oils on plasma corticosterone in broiler chickens. Acta Vet. Hung. 63:179–188.
Post, J., J. M. Rebel, and A. A. ter Huurne. 2003. Physiological effects of elevated plasma corticosterone concentrations in broiler
chickens. An alternative means by which to assess the physiological effects of stress. Poult. Sci. 82:1313–1318.
Prieto, M. T., and J. L. Campo. 2010. Effect of heat and several
additives related to stress levels on fluctuating asymmetry, heterophil:lymphocyte ratio, and tonic immobility duration in White
Leghorn chicks. Poult. Sci. 89:2071–2077.
Raabe, B. M., J. E. Artwohl, J. E. Purcell, J. Lovaglio, and J. D.
Fortman. 2011. Effects of weekly blood collection in C57BL/6
mice. J. Am. Assoc. Lab. Anim. Sci. 50:680–685.
Rattner, B. A., L. Sileo, and C. G. Scanes. 1982. Hormonal responses
and tolerance to cold of female quail following parathion ingestion. Pest. Biochem. Physiol. 18:132–138.
SCANES
Redmond, S. B., P. Chuammitri, C. B. Andreasen, D. Palić, and
S. J. Lamont. 2011. Proportion of circulating chicken heterophils
and CXCLi2 expression in response to Salmonella enteritidis are
affected by genetic line and immune modulating diet. Vet. Immunol. Immunopathol. 140:323–328.
Sapolsky, R. M., L. M. Romero, and A. U. Munck. 2000. How do
glucocorticoids influence stress responses? Integrating permissive,
suppressive, stimulatory, and preparative actions. Endocr. Rev.
21:55–89.
Satterlee, D. G., R. B. Jones, and F. H. Ryder. 1994. Effects of ascorbyl-2-polyphosphate on adrenocortical activation and fear-related behavior in broiler chickens. Poult Sci.
73:194–201.
Scanes, C. G., G. F. Merrill, R. Ford, P. Mauser, and C. Horowitz.
1980. Effects of stress (hypoglycaemia, endotoxin, and ether)
on the peripheral circulating concentration of corticosterone in
the domestic fowl (Gallus domesticus). Comp. Biochem. Physiol.
66C:183–186.
Scanes, C. G., and K. Christensen. 2014. Comparison of metaanalysis of the hematological parameters of commercial and indigenous poultry to wild birds: implications to domestication
and development of commercial breeds/lines. J. Vet. Sci. Anim.
Health. 1.
Serr, J., Y. Suh, S. A. Oh, S. Shin, M. Kim, J. D. Latshaw, and K.
Lee. 2011. Acute up-regulation of adipose triglyceride lipase and
release of non-esterified fatty acids by dexamethasone in chicken
adipose tissue. Lipids. 46:813–820.
Shlosberg, A., M. Bellaiche, G. Zeitlin, M. Yaácobi, and A.
Cahaner. 1996. Hematocrit values and mortality from ascites in
cold-stressed broilers from parents selected by hematocrit. Poult.
Sci. 75:1–5.
Selye, H. 1936. A syndrome produced by diverse nocuous agents.
Nature. 138:32.
Song, Z. G., X. H. Zhang, L. X. Zhu, H. C. Jiao, and H. Lin.
2011. Dexamethasone alters the expression of genes related to the
growth of skeletal muscle in chickens (Gallus gallus domesticus).
J. Mol. Endocrinol. 46:217–225.
Veissier, I., and A. Boissy. 2007. Stress and welfare: two complementary concepts that are intrinsically related to the animal’s point
of view. Physiol. Behav. 92:429–433.
Vicuña, E. A., V. A. Kuttappan, R. Galarza-Seeber, J. D. Latorre,
O. B. Faulkner, B. M. Hargis, G. Tellez, and L. R. Bielke. 2015.
Effect of dexamethasone in feed on intestinal permeability, differential white blood cell counts, and immune organs in broiler
chicks. Poult. Sci. 94:2075–2080.
Virden, W. S., M. S. Lilburn, J. P. Thaxton, A. Corzo, D. Hoehler,
and M. T. Kidd. 2007. The effect of corticosterone-induced stress
on amino acid digestibility in Ross broilers. Poult. Sci. 86:338–
342.
Vosmerova, P., J. Chloupek, I. Bedanova, P. Chloupek, K. Kruzikova,
J. Blahova, and V. Vecerek. 2010. Changes in selected biochemical
indices related to transport of broilers to slaughterhouse under
different ambient temperatures. Poult. Sci. 89:2719–2725.
Wang, X. J., D. I. Wei, Z. G. Song, H. C. Jiao, and H. Lin. 2012a.
Effects of fatty acid treatments on the dexamethasone-induced intramuscular lipid accumulation in chickens. PLoS One. 7:e36663.
Wang, X. J., Z. G. Song, H. C. Jiao, and H. Lin. 2012b. Skeletal muscle fatty acids shift from oxidation to storage upon dexamethasone treatment in chickens. Gen. Comp. Endocrinol. 179:319–330.
Wang, X. J., Z. G. Song, H. C. Jiao, and H. Lin. 2012c. Dexamethasone facilitates lipid accumulation in chicken skeletal muscle.
Stress. 15:443–456.
Wang, X., Q. Jia, J. Xiao, H. Jiao, and H. Lin. 2015. Glucocorticoids retard skeletal muscle development and myoblast protein
synthesis through a mechanistic target of rapamycin (mTOR)signaling pathway in broilers (Gallus gallus domesticus). Stress.
18:686–698.
Wilson, S. C., and F. C. Cunningham. 1981. Effect of photoperiod on the concentrations of corticosterone and luteinizing
hormone in the plasma of the domestic hen. J. Endocrinol.
91:135–143.
Wilson, S. C., R. C. Jennings, and F. J. Cunningham. 1984.
Developmental changes in the diurnal rhythm of secretion of
BIOLOGY OF STRESS IN POULTRY
corticosterone and LH in the domestic hen. J. Endocrinol. 101:
299–304.
Wingfield, J. C., K. S. Matt, and D. S. Farner. 1984. Physiologic
properties of steroid hormone-binding proteins in avian blood.
Gen. Comp. Endocrinol. 53:281–292.
Xie, J., L. Tang, L. Lu, L. Zhang, X. Lin, H. C. Liu, J. Odle,
and X. Luo. 2015. Effects of acute and chronic heat stress on
plasma metabolites, hormones and oxidant status in restrictedly
fed broiler breeders. Poult. Sci. 94:1635–1644.
Zhang, L., H. Y. Yue, H. J. Zhang, L. Xu, S. G. Wu, H. J. Yan,
Y. S. Gong, and G. H. Qi. 2009. Transport stress in broilers: I.
2215
Blood metabolism, glycolytic potential, and meat quality. Poult.
Sci. 88:2033–2041.
Zhao, J. P., J. Bao, X. J. Wang, H. C. Jiao, Z. G. Song, and H. Lin.
2012. Altered gene and protein expression of glucose transporter1
underlies dexamethasone inhibition of insulin-stimulated glucose
uptake in chicken muscles. J. Anim. Sci. 90:4337–4345.
Zulkifli, I., P. Najafi, A. J. Nurfarahin, A. F. Soleimani, S. Kumari,
A. A. Aryani, E. L. O’Reilly, and P. D. Eckersall. 2014. Acute
phase proteins, interleukin 6, and heat shock protein 70 in broiler
chickens administered with corticosterone. Poult. Sci. 93:3112–
3118.