AABArchives Animal BreedingAABArch. Anim. Breed.2363-9822Copernicus PublicationsGöttingen, Germany10.5194/aab-61-37-2018Relationship between different livestock managements and stress response in dairy ewesRelationship between different livestock managements and stress responseCarcangiuVincenzoArfusoFrancescaLuridianaSebastianoGiannettoClaudiaRizzoMariaBiniPier PaoloPiccioneGiuseppegiuseppe.piccione@unime.itDepartment of Veterinary Medicine, University of Sassari, Via Vienna 2, 07100, Sassari, ItalyDepartment of Veterinary Sciences, University of Messina, Polo Universitario dell'Annunziata, 98168, Messina, ItalyGiuseppe Piccione (giuseppe.piccione@unime.it)22January2018611374128July20171December201718December2017This work is licensed under the Creative Commons Attribution 4.0 International License. To view a copy of this licence, visit https://creativecommons.org/licenses/by/4.0/This article is available from https://aab.copernicus.org/articles/61/37/2018/aab-61-37-2018.htmlThe full text article is available as a PDF file from https://aab.copernicus.org/articles/61/37/2018/aab-61-37-2018.pdf
The gradual diffusion of intensive and semi-intensive production systems,
especially in dairy sheep breeds, has led to the growing concern of consumers
about the life conditions of farmed animals. Space allowance and structures
of sheep houses are described as the main potential sources of discomfort
for housed flocks, together with inappropriate milking procedures and
human–animal interactions. The aim of the present study was to evaluate
whether the structure relative to milking room could represent a stressor in
Sarda dairy ewes. Animals were divided into two groups according to their
farm of origin. Group A (n=40) was from a farm whose milking room
was an old warehouse with a waiting area limited and located outdoors and at
a different level with respect to the milking room. The passageway of the entrance in
the milking room was narrow and perpendicular to the milking positioning so
the animal must bend 90∘ to enter in the room. Group B
(n=40) was from a farm whose milking room was wide and modern
with a large waiting area located at the same level. From all animals blood
samples were collected at T0
(2 h before milking procedure at 06:00), at T1 (immediately after the animals entered the milking room,
about 08:00) and at T2 (after milking procedure). In addition plasma cortisol and
glucose values were evaluated. Statistical analysis showed significant
effect of milking room (P<0.001) and of sampling time (P<0.05) on cortisol and glucose levels. The results obtained in the present
study suggest that, in addition to milking, the characteristics of the room
where this procedure occurs represent stressful stimuli that could influence
negatively the productivity and welfare of dairy ewes.
Introduction
Animal welfare has contributed to a better understanding of how animals
perceive their social and physical environment, their motivations, and the
physiological and behavioural needs, enabling the design of environments to
better satisfy these needs (Webster, 2005). Several studies have addressed
the definition of animal welfare and the most suitable indicators to its
evaluation, particularly, in the production under intensive conditions,
where animals frequently face situations implying behavioural, physiological
and physical stress including restraint, handling or novelty, hunger,
thirst, fatigue, injury or thermal extremes (Mason and Mendl, 1993; Blokhuis
et al., 2003; Mason and Latham, 2004). Stress can be defined as a
physiological response elicited when threat to homeostasis is perceived. In
response to stressors, the central nervous system of livestock (and other
mammalian species) evokes physiological responses that ultimately result in
activation of the hypothalamo–pituitary–adrenocortical (HPA) axis and the
sympathoadrenal axis inducing endocrine and metabolic changes (Carcangiu et
al., 2008). The responses of these major systems are presumed to have
adaptive and homeostatic value during periods of stress. Reducing stress
during handling will provide advantages of increasing productivity (Grandin,
1998). The severity of the reaction is governed by a number of factors
including individual sensitivity, unfamiliarity to the stimulus and the
relative intensity (Grandin, 1997). The stress of handling can be reduced by
using well-maintained systems and the development of appropriate systems
should be guided by the requirement to ensure high standards of animal
welfare (Goddard et al., 2006). Dairy ewe production systems have
traditionally been characterized by the utilization of extensive grazing
areas (Boyazoglu and Morand-Fehr, 2001), where spatial restriction may be
considered small, or virtually non-existent. Nonetheless, the progressive
transition from traditional to modern production systems has led to the use
of more intensive husbandry procedures and higher productive efficiency in
sheep (Shrestha, 2011). The transition to modern farming systems can impose
severe restrictions on the space available for dairy sheep. The use of the
milking machine belongs to the modern farming systems and it determines a
reduction in the animals handling and, consequently, a decrease in stress
(Yardimci et al., 2013). However, the milking rooms show some critical
points that can be a source of stress. It has been demonstrated that stress
during milking can substantially reduce milk yield through a central
inhibition of oxytocin secretion and peripheral action of catecholamines
(Rushen et al., 2001). Moreover, the behavioural response of the animal to
stress can increase the risk of injury and reduce the efficiency of milking
(Rushen et al., 2001). Therefore, it is important to identify and reduce
emotional or physical stress of dairy animals during the milking process in
order to increase their productivity and to maintain their health status.
In view of such considerations, the aim of the present study was to evaluate
whether the structure relative to milking room could represent a stressor in
dairy ewe by measuring plasma cortisol and glucose levels before and after
milking procedure.
Material and methodsFarm conditions and animals
A total of 80 Sarda dairy ewes were selected from 2 farms (Farm A and B) of
sheep with a total of 200 animals each located in Sardinia (Italy) at the
same altitude (529 m above sea level) and environmental conditions. The
farms were different for milking room characteristics. In Farm A the milking
room was an old warehouse with a waiting area limited and located outdoors
and at a different level with respect to the milking room. The passageway of
the entrance in the milking room was narrow and perpendicular to the milking
positioning so the animal must bend 90∘ to enter in the
room. In Farm B the milking room was wide and modern with a large
waiting area located at the same level. From both Farm A and Farm B, 40 ewes
with a mean body weight of 41.5±0.5kg and age between 2 and 5 years
old were selected constituting Group A and Group B,
respectively.
All the animals in the study were clinically healthy with no
evidence of disease and free from internal and external parasites. Their
health status was evaluated based on rectal temperature, heart rate,
respiratory rate, appetite, faecal consistency and hematologic profile.
Fresh faecal samples were examined according to the McMaster method based on
protocols previously described by Maffa (1989). All the animals were kept in
two indoor pens under natural photoperiod (sunrise at 05:54, sunset at
19:10 over the study period) and natural environmental temperature.
Thermal and hygrometric records were carried out inside the box for the
whole study by means of a data logger (Gemini, UK), and they followed the
normal spring seasonal pattern for the location. The temperature–humidity
index (THI) value, an indicator of thermal comfort, was calculated using the
National Weather Service temperature humidity index formula for ruminant
species (Potter and Jacobsen, 2000):
THI(∘C)=T∘ ambient+(0.36⋅point of steam
condensation)+41.5.
The temperature–humidity index (THI) values calculated for Farm A and Farm B
with the respective climatic conditions are reported in Fig. 1.
Temperature–humidity index (THI) values calculated for Farm A and
Farm B with the respective environmental conditions.
All ewes were fed with a diet composed of a concentrate mixture which
consisted of the following ingredients: oat 12 %, faba bean 15 %,
barley 25 %, pea 10 %, sugar beet pulp 20 %, molasses 5 %, and
mineral and vitamins supplements 3 %. Forage-based diets were alfalfa
(Medicago sativa L.) hay. About 250 g per animal of concentrate was distributed twice a day.
Water was available ad libitum.
Lambs were weaned 35 days after birth. After weaning all ewes were milked
twice daily with the milking machine. The animals were handled every day by
the same operator.
All the animals were identified by the number plate of the local sanitary
company and by a numbered collar applied to make the recognition of
the subjects easier.
Blood sampling and laboratory analysis
From each animal of both farms blood sampling was performed by the same
operator after approximately 20 days from the start of milking to ensure the
adaptation of ewes to these procedures. Blood was sampled by jugular
venipuncture into heparinized tubes (Becton Dickinson, Plymouth, UK) at T0
(2 h before milking procedure at 06:00), at T1 (immediately after
the animals entered the milking room, about 08:00) and at T2
(after the milking procedure).
The milking procedure lasted about 10 min. The blood was immediately
centrifuged at 3000 rpm for 20 min at 4 ∘C, and the obtained plasma
samples were stored at -20 ∘C until analysis. Plasma
concentration of cortisol was measured with the Immulite 2000 (Siemens
Healthcare Diagnostic, Deer field, IL, USA), which uses a solid-phase
competitive enzyme-amplified chemiluminescent immunoassay. Plasma glucose
concentration was evaluated using an enzymatic colorimetric method
GOD-POD-PAP (Sentinel Chemical, Milan, Italy).
Protocols of animal husbandry and experimentation were reviewed and approved
in accordance with the standards recommended by the Guide for the Care and
Use of Laboratory Animals and Directive 2010/63/EU for animal experiments.
Statistical analysis
Data, expressed as mean values ± standard deviation (SD), were tested
for normality using the Shapiro–Wilk normality test. All data were normally
distributed (P>0.05) and the statistical analysis was
performed. Two-way analysis of variance (ANOVA) for repeated measure was
applied to assess significant effects of the experimental conditions
(milking room and time) on plasma cortisol and glucose levels. When
significant differences were found, Bonferroni's post hoc comparison was
applied. P values < 0.05 were considered statistically significant.
Statistical analysis was performed using the STATISTICA software package
(STATISTICA 7 Stat Software Inc., Tulsa, Oklahoma).
Mean values ± standard deviation (± SD) of plasma
cortisol and glucose obtained from dairy ewes (Group A and Group B) at T0
(2 h before milking procedure at 06:00), at T1 (immediately after
the animals entered the milking room, about 08:00) and at T2
(after milking procedure).
Results
Statistical analysis showed a significant effect of milking room (P<0.001) on plasma cortisol and glucose levels. As shown in Fig. 2, Group A
showed higher cortisol and glucose concentration with respect to Group B at T1 and T2.
A significant effect of sampling time was found on studied parameters. In
particular, higher plasma cortisol values were found at T1 and T2 with respect to
T0 in Groups A and B (P<0.05). Plasma glucose showed increased
values (P<0.05) at T1 and T2 with respect to T0 in Group A (Fig. 2).
Discussion
Domestic animals are routinely exposed to a variety of anthropogenic
stressors. Milking management represents a critical point in sheep farm. The
time animals need to adapt to machine milking, pre-parturition training to
milking parlour, and type of milking (i.e. hand or machine milking), can
markedly affect the welfare, health and production performance of dairy
sheep. Although the use of the milking machine belonging to the modern farming
systems determines a reduction in the animal handling and, consequently, a
decrease in stress (Yardimci et al., 2013), the milking rooms show some
critical points that can be a source of stress. Under stressful stimuli the
body must find a new dynamic equilibrium, and this requires several adaptive
body responses.
It is well established that season, ambient temperature, as well as THI, and
the other climatic conditions affect physiological, biochemical and
hematological parameters in sheep (Piccione et al., 2011, 2012). THI values
of 70 or less are considered comfortable, 75–78 stressful, and values
greater than 78 cause extreme distress (Di Grigoli et al., 2009). The two
farms considered in the present study showed very similar values of ambient
temperature, relative humidity and THI. THI calculated for Farm A and Farm B
was 61.78 and 63.72 ∘C, respectively, and were within
the thermoneutral zone reported for the sheep (Nikitchenco et al., 1998; Di
Grigoli et al., 2009). This excludes the influence of climatic conditions on
studied parameters.
The results obtained in this study seem to suggest that milking room
characteristics influence welfare of dairy ewes. Animals belonging to
Farm A showed statistically significant higher plasma cortisol and glucose
levels in comparison to animals of Farm B immediately after the
animals entered the milking room (T1) and after the milking procedure (T2).
Contrary to Farm B, whose milking room was wide and modern with a large
waiting area located at the same level, milking room of Farm A was an old
warehouse with a limited waiting area. Moreover, the animals of Farm A are
forced in small bunches into tight spaces before entering the milking position,
and they had to curve a rigid 90∘ to move to the
milking location. All these factors could represent stress stimuli for dairy
animals. Effectively, change in the basal level of cortisol in response to
short-term stress can be considered an important indicator of animal
welfare. Several studies carried out on sheep showed that some management
activities, including isolation, artificial milk feeding and weaning,
represent stressful conditions leading to an increase in the
blood cortisol levels (Carcangiu et al., 2008; Napolitano et al., 1995, 2003;
Orgeur et al., 1998). Animals of both considered
groups showed statistically significant higher cortisol values at T1 and T2
with respect to T0 probably due to milking procedures. Effectively, it has been
suggested that machine milking is associated with a peak in plasma cortisol
in lactating animals (Ndibualonji et al., 1995). Such phenomena may be
assimilated to suckling stimuli, which have been reported to induce the
release of corticosteroids in rats (Voogt et al., 1969). It has been
suggested that both suckling (Voogt et al., 1969) and milking (Koprowski and
Tucker, 1973) stimulate nerve endings in the nipples, which send impulses to
the brain via the spinal cord, resulting in the sequential release of
ACTH-releasing factor, pituitary ACTH, and finally adrenal corticosteroids.
The animal response to stress factors is mainly centred in the activation
of the sympathetic system and the hypothalamic–hypophysis–adrenal axis
through catecholamine and glucocorticoid production (Miller and O'Callaghan,
2002). These hormones render the animals alert, thus giving them the ability
to react to environmental stimuli, in order to preserve organic homeostasis
(Herman and Cullinan, 1997). Glucocorticoids and catecholamines also cause a
rise in glycaemia, starting from glucidic and non-glucidic substrates such
as proteins and an increase of non-esterified fatty acid (NEFA), derived
from lipid mobilization (McMahon et al., 1988). Taken together, these
effects produce a greater availability of energy for the brain and muscles,
and thereby a more efficient behavioural response to stress. Plasma glucose
concentration rose in both groups at T1 and T2 with respect to T0, although this
increase was statistically significant in Group A, only. The rise in
glucose levels is directly proportional to cortisol levels and must
therefore be attributed to the hyperglycaemic effect of this hormone, to
which we may add an increased glucose production by the liver, due to
stimulation of sympathetic–adrenergic activity (Ali et al., 2001).
Conclusion
The results obtained in the present study suggest that, in addition to
milking, the characteristics of the room where this procedure occurs
represent stressful stimuli that could influence negatively productivity and
welfare of dairy ewes. Therefore, the breeders should pay particular
attention to the structures of their farms in order to make the functional
spaces less stressful for animals.
Data are available from the corresponding author upon request.
All authors have made substantial contributions to each step of experimental
procedure and manuscript preparation: VC contributed to the experiment design and prepared the manuscript. FA performed the laboratory analysis. SL and CG performed the
sampling. RM and PPB analysed the data. GP supervised all stages
of the experimental study.
The authors declare that they have no conflict of interest.
Edited by: Steffen Maak
Reviewed by: two anonymous referees
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