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The Effect of Shearing Sheep on Feeding and
Behaviour in the Pre-Embarkation Feedlot
“A thesis submitted in partial fulfilment of the requirements for the degree of
Bachelor of Animal Science, Murdoch University”
Lourdes-Angelica Aguilar Gainza, October 2015
Supervisors: Anne Barnes, Sarah Wickham, and Teresa Collins
Table of Contents
(i) Declaration ......................................................................................................................... i
(ii) Acknowledgements ............................................................................................................ ii
Chapter 1: Literature Review
1. Introduction ................................................................................................................................................. 1-2
1.1 Live Export Industry................................................................................................................................ 2-3
1.1.1 Welfare Measures .......................................................................................................................... 3
1.1.2 Live Export Regulations ................................................................................................................ 3
1.1.3 Feedlotting ..................................................................................................................................... 3-4
1.1.4 Stress .............................................................................................................................................. 4-5
1.1.4.1 Heat Stress .............................................................................................................................. 5 -6
1.1.5 Feeding .......................................................................................................................................... 6-7
1.1.5.1 Salmonella and Inanition ......................................................................................................... 7-8
1.2 Shearing ................................................................................................................................................... 8-9
1.2.1 Shearing and Handling Stress ......................................................................................................... 9
1.2.1.1 Human-Sheep Interaction ........................................................................................................ 9
1.2.1.2 Drafting .................................................................................................................................. 9
1.2.1.3 Isolation & Restraint .............................................................................................................. 9-10
1.2.1.4 Mechanical Hand-Shears ....................................................................................................... 10
1.2.1.5 Risk of Skin Injury ................................................................................................................. 10
1.2.1.6 Habituation ............................................................................................................................. 10-11
1.2.1.7 Thermoregulation ................................................................................................................... 11
1.3 Response to Stress in Sheep ................................................................................................................... 11-12
1.3.1 Fight or Flight.................................................................................................................................. 12
1.3.2 Measures of Stress ........................................................................................................................... 12-13
1.3.2.1 Physiological Measures of Stress ........................................................................................... 13
1.3.2.1.1 Heart Rate .................................................................................................................. 13
1.3.2.1.2 Cortisol ...................................................................................................................... 13-14
1.3.2.1.3 Haematological Alterations ....................................................................................... 14
1.3.2.2 Measuring Behaviour of the Animal ..................................................................................... 14
1.3.2.2.1 Qualitative Measures of Behaviour ............................................................................ 14-15
1.3.2.2.1.1 Qualitative Behavioural Assessment .............................................................. 15
1.3.2.2.2 Quantitative Measures of Behaviour .......................................................................... 15
1.3.2.2.2.1 Ethograms .......................................................................................................... 15-16
1.3.3 Mechanisms of Feed Intake ........................................................................................................... 16-18
1.3.3.1 RFID Tags ............................................................................................................................... 18
1.4 Conclusion .............................................................................................................................................. 18-20
References ........................................................................................................................................................... 21-35
Chapter 2: Scientific Paper
2.1 Abstract .................................................................................................................................................... 36
2.2 Introduction ....................................................................................................................... 37-38
3: Materials and Methods ....................................................................................................... 38
3.1 Animals .................................................................................................................................................... 38
3.1.1 Location and Housing .................................................................................................................. 38-39
3.1.2 Environmental Measures ............................................................................................................ 39
3.2 Identification ............................................................................................................................................. 39-41
3.2.1 Feed and Water Measurements ...................................................................................................... 41-42
3.3 Shearing .................................................................................................................................................... 42-43
3.4 Body Condition Score .............................................................................................................................. 43
3.5 Filming .................................................................................................................................................... 43-44
3.5.1 Behavioural Ethograms ................................................................................................................. 44-45
3.6 Statistical Analysis .................................................................................................................................. 46
4: Results ............................................................................................................................................. 47
4.1 Environmental Conditions ....................................................................................................................... 47
4.2 Time Spent at the Feed Troughs ............................................................................................................... 47-49
4.3 Time Spent at the Water Troughs ............................................................................................................. 49-50
4.4 Body Condition Score .............................................................................................................................. 51
4.5 Behavioural Ethograms ............................................................................................................................ 51-54
5: Discussion ....................................................................................................................................... 55
5.1 Time Spent at the Feed Troughs .............................................................................................................. 55-57
5.2 Time Spent at the Water Troughs ............................................................................................................ 57
5.3 Body Condition Score .............................................................................................................................. 57-58
5.4 Behavioural Ethograms ........................................................................................................................... 58-59
5.5 Limitations ............................................................................................................................................... 59-60
6: General Conclusions ...................................................................................................................... 60
References ........................................................................................................................................................... 61-67
Declaration
“This thesis has been composed by myself and has not been accepted in any previous
application for a degree. The work, of which this is a record, has been done by myself and all
sources of information have been cited.”
(Lourdes-Angelica Aguilar Gainza)
Acknowledgements
First and foremost, I would like to sincerely thank my supervisors Anne Barnes, Sarah
Wickham and Teresa Collins; this year would have been packed full of mental breakdowns if
not for their guidance and assistance, for their enthusiasm and their confidence in me, and for
putting up with me emailing them at all times of the day and still taking time out of their very
busy day to help me out even with the silliest of questions. I would also like to thank
everyone who helped run this experiment out at the feedlot, with special mentions to Amy
Brown, David Miller, Courtney Wright and our two sheep shearers. A huge thank you to the
team down at Wellards in Mundijong for allowing us to use their sheep and facilities, and
their help making this project run as smoothly as it did. I would like to thank the Australian
Veterinary Association, Meat and Livestock Australia and Livecorp for funding this project
and allowing me the opportunity to do my project in an area of research that I’m passionate
about. Finally, I would like to thank my family for their constant love, support and
encouragement, my friends, Alexandra Kwan and Madilyn Edmonds, for keeping me sane,
Wen Jun Wong, Maddi Corlett and Vik, for dealing with my constant questions about due
dates and then dealing with the subsequent freak out when they tell me, and my office buddy,
Harry Nguyen, for having sat next to me this whole year and not complaining once.
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Chapter 1. Literature Review
1.Introduction
The focus of this review is shearing and its role in the intensive Australian live export
industry, especially in terms of its effect on feed intake and feed behaviour of sheep held in
pre-embarkation feedlots. Live export of sheep is playing a bigger role in Australia and
becoming increasingly more important, with Australia being one of the world’s leading
producers of mutton and lamb, and exporting 20,020,941 head for live sheep in 2013-2014
(MLA, 2015a). The largest market demand for live Australian sheep is from the Middle East,
where 97% of Australian live sheep were exported for 2013-2014 (MLA, 2015a).
Sheep are exposed to contrasting environments being exported from an Australian
winter, where temperatures can drop to 6-12°C (Wells, 2013), to the summer of the Middle
East, where temperatures can reach 41.9°C (Qatar Meteorology Department, 2013). There
has been extensive research done to understand the responses in the sheep when they
experience large heat loads, with responses including increased respiratory rate, body
temperature and water consumption, and decreased feed intake (Monty et al., 1991; Dixon et
al., 1999; Beatty et al., 2008), with shorn sheep responding to heat loads better than fleeced
sheep (Beatty et al., 2008). Due to this, regulations are in place to ensure that sheep that are
sourced for live export have been shorn at the pre-embarkation feedlot prior to loading onto
the live export vessel.
On-farm, sheep shearing is an annual event usually done just before lambing to reduce
wool fouling and allows for the removal of wool off a sheep (Devlin et al., 1989). This also
occurs during the pre-embarkation feedlot period. However there are a combination of factors
that are involved with shearing, rather than just wool removal, including sheep being
approached by a human, moved along a race, penned, caught, upended and then dragged to
the shearing station to be shorn (Devlin et al., 1989), as well as the risk of skin injury
(Hargreaves & Hutson, 1990a). All these factors cause a physiological response in the sheep,
including increases in heart rate (Hargreaves & Hutson, 1990c) and cortisol (Kilgour &
DeLangen, 1970), and could cause sheep to become susceptible to Salmonella and inanition,
which are major causes of mortality in the live export industry (Norris & Richards, 1989b).
There are gaps of knowledge when it comes to the effect of shearing stress on the
behaviour of sheep, and therefore further studies are needed to understand the association
between shearing on feeding patterns and observed behaviour responses, and the duration of
these changes. Understanding if and when sheep are stressed during feedlotting will indicate
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where the welfare risks are and could assist in promoting management practices that reduce
the incidence of abnormal feed behaviour.
This literature review will consider the live export and feedlotting sheep industry and
examine physiological and behavioural responses of sheep to stress of management practices,
particularly shearing.
1.1. Live Export Industry
Australia is the largest exporter of mutton and live-sheep as well as the second largest
exporter of lamb, with an off-farm meat value of the Australian sheep meat industry, worth
$4.2 billion Australian dollars (MLA, 2015b). The statistical review of livestock export for
2013-2014 (Levonian, 2014) showed that Australian exports totaled 20,020,941 head for live
sheep valued at $185 million Australian dollars (MLA, 2015a). Australia exported 97% of
Australian live sheep exports to the Middle East for the year of 2013-2014 (MLA, 2015a),
with Kuwait as the largest market for live sheep (37.6%), followed by Qatar (26.1%), Jordon
(14.6%), United Arab Emirates (6.2%), Israel and Bahrain (5%), Oman (3.1%) and other
(2.6%) (Levonian, 2014). Live export is an important aspect of Australian primary industry
because it is able to supply an alternative market for livestock produce, especially for sheep
growing areas in Western Australia (Keniry et al., 2003).
The live export chain begins on-farm where farmers prepare and select the livestock,
selecting only sheep that fit the criteria to be sourced for live export (Australia. Department of
Agriculture, Fisheries & Forestry., 2011). Rejection of sheep may occur if sheep are, for
example, lactating or have wool that is more than 25mm in length (Australia. Department of
Agriculture, Fisheries & Forestry., 2011). The sheep are then loaded onto a vehicle and
transported to a registered pre-embarkation premise where they are housed for at least 3-5
days (Australia. Department of Agriculture, Fisheries & Forestry., 2011). Sheep are then
transported to the port and loaded onto a live export vessel for the sea voyage, with an
average 17-day voyage length (Norris & Norman, 2013). The end of the production chain is
after disembarkation at the overseas port, and when the last of the livestock have been
unloaded from the vessel (Australia. Department of Agriculture, Fisheries & Forestry., 2011).
Due to welfare risks, the industry does not have the universal support of the Australian
public (Whan et al., 2003). A stated concern of opponents is that live export presents too
great a risk to wellbeing and health of the exported livestock (Whan et al., 2003). Public
apprehension may be traced to the relatively small amount of high impact incidents in the
export industry (Keniry et al., 2003). An example of a high impact incident was the Cormo
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Express incident in 2003, where 57,937 sheep were bound for Saudi Arabia only to be
rejected due to the diagnosis of contagious pustular dermatitis, also known as scabby mouth,
in 6% of the sheep (Keniry et al., 2003). After being rejected, the vessel was at sea for 80
days, rather than the intended 2 weeks, and there had been 5,691 (9.28%) sheep deaths by the
time it had reached another market in Eritrea (Keniry et al., 2003). Whilst these incidents are
rare, they have high media exposure and cause outrage amongst stakeholders, including the
public.
Therefore, a considerable risk to sustainability of the live export industry is the
public’s apprehension of the welfare of these animals. Standards are necessary in
management systems throughout the chain to deliver acceptable outcomes of welfare of the
animals and promote positive public perception towards the industry (Whan et al., 2003).
1.1.1. Welfare Measures
Currently, during live export, animal welfare is measured in two different ways; one is using
mortality rates, with a reportable mortality rate for sheep in live export vessels being higher
than 2% of the consignment; and the other is the assessment of specific environments, such as
pen design or truck suitability for certain species (Whan et al., 2003). Mortality is a primary
measure for health and welfare because it is a robust measure of performance; at this point in
time, there are no other alternative measures that are without bias and at minimal cost that can
be used for live export (Whan et al., 2003). Animals involved in live export are exposed to
welfare and disease challenges due to unfamiliar environments, social change and higher
stocking density, and these less-than-ideal standards of care may lead to higher mortality rates
when compared to an on-farm setting (Whan et al., 2003).
1.1.2. Live Export Regulations
Regulations are in place to ensure the welfare and health requirements for all livestock.
Regulations include the type of livestock to be sourced, including the classes of sheep (e.g.
not pregnant ewes or very fat wethers over body condition score 4), the requirement for
spending a set time in registered premises being fed the pelletised feed typical of the ship
board diet, and the management of wool cover (Australia. Department of Agriculture,
Fisheries and Forestry., 2011).
1.1.3. Feedlotting
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Registered premises are establishments that are used for the preparation of livestock for live
export by sea, including pre-embarkation feedlots. The pre-embarkation feedlot is an
intensive finishing system to ensure livestock are adequately prepared to undergo the export
voyage and is regulated by the Australian Live Export Standards (Australia. Department of
Agriculture, Fisheries and Forestry., 2011). A finishing system can be characterised as the
method of feeding for lambs that will deliver energy and protein requirements for the ideal
daily live weight gain that will allow for the carcass weights to be suitable for importing
countries requirements (Victoria. Department of Environment and Primary Industries., 2015).
Sheep may be considered adequately prepared to undergo the export voyage when
they are accustomed to the pelletised feed diet that is found aboard the live export vessel
(Norris et al., 1990). Therefore, specific requirements for the pre-embarkation feedlot include
the minimum feed requirements where sheep younger than 4 tooth (less than 18 months)
should eat 3% of their bodyweight per day and sheep 4 tooth or older (older than 18 months)
should eat 2% of their bodyweight per day as a fundamental quantity of feed that will be able
to meet daily maintenance (Australia. Department of Agriculture, Fisheries and Forestry.,
2011). Sheep held in registered premises south of latitude 26° held in paddocks from May to
October must be held at the premises for 5 clear days before export, not including days of
arrival and departure (Australia. Department of Agriculture, Fisheries and Forestry., 2011).
These sheep must have ad libitum fed and during the last 3 days must only be fed the
pelletised feed equivalent to that found on the export vessel (Australia. Department of
Agriculture, Fisheries and Forestry., 2011). Sheep held in registered premises south of
latitude 26° that are held in paddocks from November until April as well as sheep that are
held in sheds for any or all months of the year must be kept at the registered premises for 3
clear days, not including the days of arrival and departure, as well as being fed pelletised feed
equivalent to the feed used on the vessel and being fed ad libitum (Australia. Department of
Agriculture, Fisheries and Forestry., 2011).
1.1.4. Stress
Sheep entering the live export chain will have experienced increased handling, road
transportation, vaccinations, drafting, shearing, altered diets, novel forms of feed, novel
environments as well as the journey on the live export ship itself, all occurring over a period
of around one month (Norris et al., 1989a). These factors can cause stress in sheep (Kilgour
& DeLangen, 1970; Hargreaves & Hutson, 1990a, 1990b; Doyle et al., 2010; Sanger et al.,
2011), which can result in decreased feed intake and inanition leading to mortality (Norris &
5
Richards, 1989b; Barnes et al., 2008; Perkins et al., 2009). One source of stress for sheep
during the feedlotting period is shearing; however shearing is in place as a method to reduce
heat stress, which is a significant risk factor within the live export industry.
1.1.4.1 Heat Stress
Sheep are exposed to contrasting environments during live export (Beatty et al., 2008)
especially if they move from an Australian winter, where temperatures can drop to 6-14°C
(Australian Government, 2013), to the summer climate of the Middle East, where temperature
of importing countries such as Qatar can have an average humidity of 50% and average
temperature of 41.9°C that is unlikely to drop below 30°C at night for July (Qatar
Meteorology Department, 2013). Norris and Richards (1989b) determined that the relative
humidity and temperature in ships almost never surpassed 90% and 32°C dry bulb
respectively, with Bailey and Fortune (1992) describing temperatures reaching 35°C dry bulb
on some locations on the export ship.
Heat stress is a result of the effect of any number of environmental conditions on an
animal, such as air temperature, relative humidity, air movement and solar radiation (Bianca,
1962). These variables cause the effective temperature of the environment to be greater than
the animals’ thermo-neutral zone, where heat loss and heat production are the same (Bianca,
1962), with the thermo-neutral zone for an adult sheep in full fleece being between 12 and
32°C (Srikandakumar et al., 2003). During live export, this thermoneutral zone is often
exceeded, as the air on the export vessel can be hot and humid, with addition of heat produced
from the animals (Barnes et al., 2004). These hot and humid conditions are maintained
during the day, with little relief at night (Barnes et al., 2004). Therefore regulations are in
place to reduce the heat load, such as limits on the amount of wool a sheep can have before it
is exported from Australia.
Rectal temperature is an important reflection of thermal stress in sheep (Monty et al.,
1991). Rectal temperatures have been shown to rise above normal when ambient
environmental temperatures increase above 32◦C in sheep. At a rectal temperature of 40◦C,
open mouth panting will begin, acting as an important cooling mechanism occurring during
large heat loads (Dixon et al., 1999; Srikandakumar et al., 2003; Phillips & Santurtun, 2013).
As temperature on-board the live export ship can reach 35°C (Bailey & Fortune, 1992), it is
biologically feasible that many sheep will undergo heat stress during the journey to the
Middle East and therefore it would be in the best interest for welfare of the sheep that heat
6
load be reduced as much as possible. This is one critical reason for shearing. Klemm (1962)
found that shorn sheep were better able to tolerate hot, humid environments, similar to those
found during shipping, compared to unshorn sheep. It was determined that fleece in hot,
humid environments facilitated an increase in radiant heat load rather than acting as a barrier
to heat (Klemm, 1962). Once shorn, sheep are able to respond to heat loads better than
fleeced sheep; fleeced sheep had higher body core temperature, higher rumen temperature,
increased respiratory rates and water intake compared to shorn sheep (Beatty et al., 2008).
Heat stress can cause a decrease in voluntary dry matter intake of feed and
metabolizable energy leading to a decrease in expenditure of body heat (Marai et al., 2007).
The result of heat stress is increased respiratory rate, body temperature and water
consumption, and a decreased intake of feed (Monty et al., 1991; Dixon et al., 1999; Marai et
al., 2007; Beatty et al., 2008). The increase in water consumption due to heat stress may be
due to animal attempting to compensate water loss due to increased evaporation of the skin
surface and respiratory tract (Indu et al., 2015). The reduction in feed intake can be seen as a
critical response to a hot environment where in order to maintain thermoneutrality, sheep
must produce less heat (Marai et al., 2007) and may do this by reducing the amount of
metabolic heat and heat from ruminal fermentation (Monty et al., 1991).
These studies are important to understand as they demonstrate how environmental
conditions are able to influence how sheep cope with external stimuli of hot temperatures and
the consequence this has on sheep appetite in terms of reduced feed intake, with inanition
being a substantial issue for mortality in the live export industry.
1.1.5. Feeding
The main causes for shipboard death of sheep have been identified as inanition and
salmonellosis (Norris & Richards, 1989b), accounting for approximately 75% of mortality in
live sheep export industry (Makin et al., 2010). The risk of sheep acquiring persistent
inappetance syndrome and subsequent death via inanition is higher in the live export industry
compared to other livestock industries (Norris et al., 1990). There was a high risk of death on
the live export ship when sheep did not eat pellets late in the pre-embarkation feedlot period,
which indicated that mortality on board the ship was linked to sheep inappetance late in the
feedlot period (Norris et al., 1989c). Bailey & Fortune (1992) demonstrated that although the
length of time in the feedlot did not seem to affect the live weight of the sheep, those sheep
that died at sea had a mean weight loss greater than 13 kg and exhibited tissue loss, indicating
that weight loss could have begun at the feedlot. Therefore feeding behaviour in the pre-
7
embarkation feedlot can influence subsequent health and mortality of shipped sheep.
1.1.5.1. Salmonella and Inanition
Inappetance during the feedlot period can predispose the sheep to developing salmonellosis
(Higgs et al., 1993). In the live sheep export industry there are two different syndromes of
salmonellosis: feedlot-related salmonellosis and the persistent inappetance-salmonellosis-
inanition (PSI) complex (More, 2002). Feedlot-related salmonellosis occurs mostly during
feedlotting where animals are exposed to heavy loads of Salmonella organisms (More, 2002).
The PSI complex is a prominent cause of sheep mortality during live export on the vessel
where exported sheep fail to eat at any stage of the live export chain after leaving farm-of-
origin (More, 2002). These animals will ultimately die from inanition, unless they succumb
to salmonellosis first (More, 2002).
It was established that Salmonella organisms, in particular Salmonella Chester, S.
typhimurium, S.muenchen, S. oranienburg, S.anatum and S.adelaide, were able to be quickly
eliminated from the rumen of cattle if the animals were maintained on a full feed; however, if
the feed was reduced by one third of normal intake, the Salmonella organisms greatly
increased in number in the rumen and faeces of the animal (Brownlie & Grau, 1967).
Therefore, inconsistent or irregular feed intake leading to rumen dysfunction (More, 2002) is
a critical predisposing factor of the Salmonella organism at the pre-embarkation feedlot
(Norris et al., 1989c, 1990). However, an inherent part of sheep management is feed
deprivation, occurring due to novel feeds and during mustering, yarding, drafting and
transport, and is likely to be responsible for an increased susceptibility to Salmonella
organisms (Perkins et al., 2009). High concentrations of volatile fatty acids and low rumen
pH (below 5.5) inhibit Salmonella growth in the rumen (Mattila et al., 1988). If sheep do not
eat, due to feed interruption or through anorexia, then production of volatile fatty acids is
decreased and the pH of the rumen will rise to 7-7.5 favouring growth of Salmonella in the
rumen, compared to a regularly fed ruminant (Brownlie & Grau, 1967).
Stress one of the more important factors that influence the chance of survival from
inanition and the severity of Salmonella lesions (Higgs et al., 1993). Higgs et al. (1993)
showed increased adrenal gland weights were correlated to the presence of septicaemic
salmonellosis, which suggests that the infection was predisposed by a severe degree of stress
and these sheep were not able to cope with the challenge of the Salmonella infection. It is
also biologically feasible that there will be greater losses in animals that survive a feedlot-
related salmonella outbreak compared to those that have not, with these ‘survivors’ being very
8
likely to act as passive, active or pre-incubatory carriers during loading onto export ship
(More, 2002). As a result of this, the animals on-ship have an increased risk of developing
the clinical disease following stress of transport, loading onto the export ship and unfamiliar
shipboard environment (More, 2002).
This demonstrates how important it is that sheep during the pre-embarkation feedlot
do not alter their feed behaviour or reduce intake such that the animal has an increased
susceptibility to Salmonella. Thus, it is important to understand the long-term effects of feed
intake and feed behaviour at the pre-embarkation feedlot as there could be carry-over effects
on shipboard mortality, particularly deaths due to inanition. If inanition is beginning at the
pre-embarkation feedlot period, it is necessary to understand what factors are causing changes
in feed intake and weight loss of sheep. Therefore, stress factors should be investigated to
determine if they impact on the feeding of sheep during the pre-embarkation period.
1.2. Shearing
While on-farm, sheep shearing is usually done just before lambing (Devlin et al., 1989).
Sheep must be shorn because wool will continually grow, become fouled by faeces and cause
discomfort to the sheep (Devlin et al., 1989). Discomfort may occur as a result of the
additional weight of the fleece, as well as the sheep becoming wool-blind (Devlin et al.,
1989). Dags, accumulated soft faeces found on the breeches of sheep (Davidson et al., 2006),
may cause the sheep to become more susceptible to external parasites or blowflies leading to
flystrike (Levot, 2009), as well as causing mortality of lambs due to the difficulty in suckling
due to excess wool (Devlin et al., 1989).
In Australia, shearing is generally done once a year, depending on farmer preference
and shearer availability, with peak shearing occurring from April to November (Devlin et al.,
1989). The average time taken to shear is dependent on sheep size, degree of body wrinkle
and the fleece characteristics of the sheep, but generally takes approximately 1.5 to 3 minutes
using an experienced shearer (Devlin et al., 1989). Shearing allows for the removal of the
wool off a sheep, using a shearing machine consisting of a metal hand-piece with a comb and
cutter (Devlin et al., 1989). The sheep are yarded, moved along a race, penned, caught,
upended and then dragged to the shearing station to be shorn (Devlin et al., 1989). Shearing
also exposes sheep to the noise and vibration of the shearing hand-piece and risk of skin
injury (Sanger et al., 2011).
9
It is the combination of these factors that mean shearing could compromise sheep welfare
(Sanger et al., 2011). However, despite this, sheep exported to the Middle East must have
wool not longer than 25mm in length, be 10 days or more since shearing, or if they are to be
shorn during the 10 day period before shipping, this must occur while the animals are
accommodated in sheds on registered premises (Australia. Department of Agriculture,
Fisheries and Forestry., 2011). Therefore, if sheep sourced for export have wool more than
25 mm in length, they must be shorn prior to leaving the pre-embarkation feedlot before
export.
1.2.1 Shearing and Handling Stress
Shearing primarily involves the act of wool removal; however, other factors of the procedure
contribute to sheep stress. Therefore, these factors must also be taken into consideration
when attempting to understand the physiological or behavioural responses the sheep undergo
post-shearing.
1.2.1.1. Human-Sheep Interaction
Shearing involves human-sheep interactions, where humans must approach sheep for drafting,
capture, dragging and shearing, with the potential addition of the presence of a dog that may
be used for working the sheep (Devlin et al., 1989). The human-sheep interaction has the
potential to cause stress for the sheep. MacArthur (1982) and MacArthur et al. (1979) found
that when a dog and a human approached free-ranging bighorn sheep, there was an increase in
heart rate at distances 20-50 metres. Although dogs have been seen to produce larger
increases in heart rate and alert behaviour, a human approaching a sheep can also cause an
increase in heart rate of the sheep (Baldock & Sibly, 1986; Hargreaves & Hutson, 1990c).
1.2.1.2. Drafting
Sheep were moved to the shearing shed to be housed in pens before shearing. However the
stress of drafting may differ depending on the method of handling. When a person stood
behind the sheep yelling and using arm movements to push the sheep, an increase in plasma
cortisol that peaked at 10 minutes post-drafting was shown, and this was considerably higher
than in the control sheep that were not drafted (Hargreaves & Hutson, 1990b).
1.2.1.3. Isolation and Restraint
Shearing involves capture of sheep and physical restraint, with periods of isolation from other
10
sheep while the procedure of wool removal is occurring (Devlin et al., 1989). Isolation of
sheep is known to cause distress, associated with increased cortisol levels (Kilgour &
DeLangen 1970), and increased heart rate (Syme & Elphick, 1982), indicating the strong
social nature of sheep and their aversion to being isolated.
Isolation stress leads to both physiological and behavioural changes. Increased plasma
epinephrine levels as well as serum concentrations of lactate, glucose, insulin and free fatty
acids have been shown (Carbajal & Orihuela, 2001). It also causes an increase in pH, and a
decrease in glycogen and lactate concentrations in the muscle (Apple et al., 1995). There is
an increase in adrenocorticotropic hormone plasma concentrations (Minton & Blecha, 1990),
production of leukocytes (Minton et al., 1992), glutamic oxaloacetic transaminase (Apple et
al., 1995), as well as increased vocalization, general activity (Price & Thos, 1980) and
eliminative behaviours (Le Neindre et al., 1993).
1.2.1.4. Mechanical Hand-Shears
Hargreaves and Hutson (1990c) determined that the noise of shearing caused an increase in
haematocrit and cortisol levels. This may be due to the conditioned response to shearing
when the sheep hear the noise of the mechanical hand-shears and the response to a procedure
that leads to shearing itself as the resemblance between the two increases (Hargreaves &
Hutson, 1990c). It may also be due to the noise itself evoking the responses where it is able
to confer auditory isolation of the sheep due to the fact that when sheep are up-ended, they are
visually isolated and hearing may be more important in this situation for the sheep to monitor
the surroundings (Hargreaves & Hutson, 1990c). The heat, vibration and contact of the shears
may also have the potential to cause a response from the sheep (Hargreaves & Hutson,
1990a).
1.2.1.5. Risk of Skin Injury
There is a positive correlation between shearing injury scores and elevation of plasma glucose
concentration; at 90 minutes, glucose concentration remained elevated for longer if the animal
had a greater number of injuries or had more severe cuts (Hargreaves and Hutson, 1990a).
However, there is an absence of correlation between shearing injuries and peak haematocrit or
cortisol levels which indicates that there is a delayed response to injury, occurring after
transient psychological factors, including fear or startling (Hargreaves & Hutson, 1990a).
1.2.1.6. Habituation
11
Carcangiu et al. (2008) as well as Hargreaves and Hutson (1990d) found that the cortisol
levels, in sheep that were being shorn for the first time compared to those that had been shorn
in the prior years and 2 weeks apart respectively, were not different. They were therefore able
to confirm that sheep do not become accustomed to the stressful procedure of shearing
(Hargreaves & Hutson, 1990d; Carcangiu et al., 2008).
1.2.1.7. Thermoregulation
Shearing has the capacity to affect thermoregulation of sheep. Thwaites (1966) found that
unshorn sheep best tolerated hot dry atmospheres, with hot humid environments being
tolerated best by shorn sheep (Klemm, 1962). Therefore, fleece length can affect the heat
exchanged with the environment (Beatty et al., 2008). If environmental temperature is lower
than that of the animal’s body temperature, the absence of fleece will allow for efficient heat
dispersal via conduction, radiation and evaporation (Piccione & Caola, 2003). When fleece is
present at these temperatures, respiratory evaporative heat loss is more heavily depended on,
with 65% of total heat loss coming from panting compared to the 59% in shorn sheep
(Hofman & Reigle, 1977), with increased respiratory rates and water intakes occurring in
fleeced sheep, possible indicating respiratory water loss due to panting (Beatty et al. 2008).
The stress response in sheep may also manifest as stress-induced hyperthermia, which
is a common response to psychological and emotional stress (Sanger et al. 2011). As sheep
do not become accustomed to shearing (Hargreaves & Hutson, 1990d; Carcangiu et al.,
2008), the anticipation of a stressful event, such as shearing, can generate stress-induced
hyperthermia increasing the core temperature in sheep that had been shorn previously (Beatty
et al. 2008; Sanger et al. 2011).
1.3. Responses to Stress in Sheep
Stress can be defined as the experience of having extrinsic or intrinsic demands that are
greater than the resources the individual has for responding to these demands (Dantzer, 1991).
Living systems have evolved in such a way that allow for a reduction in these extrinsic or
intrinsic demands and for maintenance of the status quo through a series of behavioural and
physiological responses (Morgan & Tromberg, 2007). Maintaining the status quo can be
referred to as homeostasis (Morgan & Tromberg, 2007) and therefore a factor that challenges
homeostasis may be defined as a ‘stressor’ (Selye, 1956). A stressor could either be a
physical challenge to homeostasis, including temperature changes, restraint and isolation, or
shearing, or the threat of a challenge to homeostasis (Morgan & Tromberg, 2007). These
12
stressors will both lead to a series of physiological events, or responses, which will prepare
the animal for the homeostatic challenge; whether it will be fight or flight (Morgan &
Tromberg, 2007).
1.3.1. Fight or Flight
When confronted by a stressful situation, or a ‘stressor’, animals will react in a predictable
way that involves a set of physiological reactions that will lead to a fight-or-flight end point
(Selye, 1976). Seyle (1976) found that the first effect of a stressor that acts upon the body is
the production of a non-specific stimulus, that is the humoral messenger corticotropin-
releasing factor. The corticotropin-releasing factor increases the secretion of
adrenocorticotropic hormone that causes production of corticosteroids and autonomic nervous
system-induced release of catecholamines (Seyle, 1976). This cascade outlines the fight or
flight to either ready to body to confront the threat, the fight response, or to escape the threat,
the flight response (McCabe & Milosevic, 2015).
Fight or flight may manifest in a wide range of responses, with acute, short-term
stressors generally being correlated with behavioural responses of alarm, orientation and
increased vigilance (Morgan & Tromberg, 2007). The physiological factors of this response
to short term stressors include increased respiration rate, tachycardia, increased glucose
metabolism, increase in glucocorticoids and a move away from energy conservation (Morgan
& Tromberg, 2007). Chronic stress may be signified by a dulled stimulation of the
hypothalamic-pituitary-adrenal (HPA) axis response to acute stress (Goliszek et al., 1996),
suppressed immune responses found in pigs (Barnett et al., 1992), and decreased body weight
in mice (Konkle et al., 2003; Bartolumucci et al., 2004). Chronic stress may also influence
behaviour of the animal in terms of increased abnormal behaviour (Carlstead & Brown, 2005)
and increased freezing behaviour (Korte, 2001), that is the absolute absence of body
movement (Brandão et al., 2008)
Due to the diverse range of behavioural and physiological changes in the animal
resulting from acute or chronic stress, both qualitative and quantitative measures may be used
in conjunction with one another to further validate the response an animal has to a stressor.
1.3.2. Measures of Stress
Physiological and behavioural measures are often used to measure stress. However, it may be
noted that a given behavioural or physiological measure will not always display a particular
experience (Fraser & Duncan, 1998). For example, behaviour such as running could indicate
13
different experiences of excitement or fear, while a certain experience such as fear can lead to
different behaviours, including running (Wemelsfelder & Farish, 2004). This can also be seen
with physiological processes where plasma cortisol increases may be seen in stressful events
(Baldock & Sibly, 1990; Hargreaves & Hutson, 1990c), but also during enjoyable events
(Rushen, 1986). Therefore, measuring stress and an animal’s emotional state is a complicated
process that uses different physiological and behavioural measures in conjunction to verify
that an interpretation of an animal’s state is correct (Wemelsfelder & Farish, 2004).
1.3.2.1. Physiological Measures of Stress
Despite the uncertainties of the use of physiological measurements, many experiments have
often used physiological reactions in the sheep as parameters to whether the sheep is
undergoing stress. These parameters of stress that are most commonly used are heart rate,
cortisol and haematocrit.
1.3.2.1.1. Heart Rate
The second line of defense towards a stressor is the autonomic nervous system (Moberg,
2000). The autonomic nervous system works by affecting a wide range of biological systems,
including the cardiovascular system (Moberg, 2000). Due to this reason, heart rate has been
regularly used to determine stress levels of animals under stressful conditions (Reefmann et
al., 2009).
Hargreaves and Hutson (1990c) monitored the heart rate of sheep before, during and
after different handling treatments and found that partial shearing significantly increased heart
rate during the treatment, and heart rate was highest until 3 minutes post-treatment. Only a
small proportion of fleece was removed and heart rate decreased to resting levels within one
hour, showing that acute increases in heart rate are after shearing are not likely to be due to
thermoregulatory adjustments (Hargreaves & Hutson, 1990c).
1.3.2.1.2. Cortisol
Cortisol levels are used to measure stress as they are able to reflect the pituitary-adrenal and
catecholamine response and signify a non-specific response to stress factors (Dantzer &
Mormede, 1983). The cortisol concentration of sheep after shearing has been determined
through blood samples of the shorn sheep, taken via jugular venipuncture (Hargreaves &
Hutson 1990a, 1990b; Mears et al., 1998; Carcangiu et al. 2008; Doyle et al. 2010;). This
method has been used to determine the physiological stress of shearing (Hargreaves & Hutson
14
1990a, 1990b, 1990c; Mears et al., 1998; Sanger et al. 2011) and restraint and isolation
treatments (Degabrielle & Fell, 2001; Wrońska-Fortuna et al., 2009; Doyle et al. 2010).
Hargreaves and Hutson (1990c) showed an increase in plasma cortisol in sheep after shearing
that continued longer than other handling treatments including isolation. Sham shearing,
where the movement, noise and manipulations of shearing were carried out but no wool
shorn, was also able to increase plasma cortisol, indicating that other factors besides wool
removal cause stress for the sheep (Hargreaves & Hutson, 1990a).
1.3.2.1.3. Haematological Alterations
Increased numbers of neutrophils (neutrophilia), and decreased lymphocytes (lymphopenia)
are main haematological alterations that occur in response to glucocorticoids or stress (Davis
et al., 2008). Doyle et al. (2010) found that sheep exposed to restraint and isolation stress had
increased neutrophil concentrations and decreased lymphocytes compared to sheep that were
not exposed to restraint and isolation.
1.3.2.2. Measuring Behaviour of the Animal
Although physiological measures are informative, they may be limited in terms of how they
are applied, measured and interpreted (Wickham et al., 2015). Physiological measures are
often invasive and thus, the measurement of the physiological variables may affect the animal
or cause difficulty in determining a baseline or normal range (De Silva et al., 1986). Timing
of sampling is important with measures of physiological variables; responses of the HPA axis
could be overlooked if the measurements are not carried out at appropriate times (Wickham et
al. 2015). Thus, there is often a need to consider non-physiological indicators of welfare,
such as behaviour
Animals may have altered behaviour as their first response due to a stressor or
aversive environment (Temple et al., 2011). Behaviours that differ, in terms of patterns or
frequency, from the normal repertoire of activities that species exhibit when they are in
conditions that allow a full range of behavioural expression, can be considered ‘abnormal
behaviors’ (Fraser & Broom, 1990). These alterations from normal species-specific
behaviours may be measured using a wide range of methods that can be categorized as
quantitative and qualitative measures.
1.3.2.2.1. Qualitative Measures of Behaviour
Qualitative measures are non-numerical observations that can be represented by measurement
15
on an ordinal or categorical scale (Martin & Hine, 2008) and can be used to interpret
behaviour by describing how an animal is performing a particular behaviour (Wickham et al.
2015).
1.3.2.2.1. Qualitative Behavioural Assessment
Qualitative Behavioural Assessment (QBA) is a method of assessment describing the
animal’s affective state (Rutherford et al., 2012). QBA works as a whole-animal approach
where human observers discern an animal’s behavioural expression, using qualitative
descriptor words, for example ‘relaxed, anxious, or content’, to display the affective state of
the animal (Wemelsfelder, 1997, 2007). QBA uses human observers to understand how the
animal interacts with their environment to interpret how the animal is behaving rather than
what the animal is doing, and in this way the observer summarizes all details of the movement
and posture of the animal into descriptions of the expressed demeanor (Wickham et al. 2015).
Therefore, QBA can be used to identify subtle changes in animal demeanor that may be
overlooked due to isolation if quantifying the physical behaviours of individual animals
(Wemelsfelder, 1997; Meagher, 2009; Whitham & Wielebnowski, 2009).
This method of qualitative assessment has been demonstrated in pigs (Wemelsfelder et
al., 2000, 2001, 2009; Temple et al., 2011; Rutherford et al., 2012) and other species
including horses (Napolitano et al., 2008; Minero et al., 2009; Fleming et al., 2013), poultry
(Wemelsfelder, 2007), dogs (Walker et al., 2010), cattle (Rousing & Wemelsfelder, 2006;
Brscic et al. 2009; Stockman et al., 2011, 2012, 2013), and sheep (Wickham et al., 2012).
Wickham et al. (2012) determined a correlation between observers’ use of the
descriptor words ‘anxious, nervous and worried’ with concentrations of plasma IGF-1,
neutrophils: lymphocyte ratios, monocyte and basophil counts, heart rate, and core
temperature in sheep, and therefore there is validation of the use of QBA through the
correlation between physiological parameters and behavioural expressions of livestock.
1.3.2.2.2. Quantitative Measures
Quantitative measures of behaviour refer to observations that are represented in numerical
quantities (Mathison, 2005). Using numerical quantities, for example how many times an
animal performs a particular behaviour or for how long they perform the behaviour can be
important when measuring the effect of stress on behaviour.
1.3.2.2.2.1. Ethograms
16
Ethograms are a list of species-specific behaviours that outline the aspects and functions of
the behaviours listed (Stanford School of Medicine, 2015). Ethograms may be used to
categorize movements and postures into behavioural patterns that can then be used as a
descriptive basis to analyze behaviour in a quantitative manner (Stevenson & Poole, 1974).
For example, the species-specific list of behaviours of fear in sheep could include a tense
‘frozen’ posture, stiff movements, and focused visual and auditory vigilance (Wemelsfelder &
Farish, 2004). Measuring the amount of times the animal expresses particular behaviours
could indicate the valence or state of the animal under the specific conditions and
environment. Ethogram analysis may be a beneficial, non-invasive method to study the effect
of shearing of sheep by comparing the ethograms before and after the procedure, especially
with respect to the patterns and duration of behavioural activities. Ethograms can then be
used to construct activity budgets.
Activity budgets will be able to give an indication of the time sheep spend doing a
particular behaviour, which could assist in determining if sheep allocate more or less time
doing a particular behaviour, for example feeding. Vasseur et al. (2006), using ethograms and
time budgets, found that the amount of time spent wool biting increased in sheep after five
weeks of concentrated-fed housing, and this behaviour was then decreased by the provision of
fibre in their diet. The study found that the behaviour of wool biting was associated with the
sheep’s requirement for fibre and that wool biting is at least partially established due to the
absence of natural substrate for grazing and for oral stimulus through eating and ruminating
(Vasseur et al., 2006). This gives an example of how feeding and behaviour are correlated to
one another, and therefore it would be feasible to use ethograms and time budgets to
determine if a stressor, such as shearing, may cause an altered feed pattern and behaviour in
sheep.
1.3.3. Mechanism of Feed Intake
To understand whether an animal will spend more or less time feeding after a stressful event,
such as shearing, the mechanisms of feed intake, and in this case inanition, must be
understood. Energy sources include carbohydrates, amino acids and fats, where
carbohydrates are the primary energy source in animals (Makin et al., 2010). If there is not
enough energy to be consumed to meet the animal’s need, due to inappetance or feed
restriction, then a negative energy balance is generated (Makin et al., 2010). Interrupted feed
intake may occur due to management procedures such as mustering, drafting, yarding, or road
transport and prolonged negative energy balance can result in ketosis and inanition (Makin et
17
al., 2010). During a negative energy balance state, there is a decrease in insulin
concentration compared to glucagon (Barnes et al., 2008), and therefore muscle and fat are
metabolized and used to produce energy, while carbohydrates are synthesized from proteins
(Makin et al., 2010). Body fat contains triglycerides comprised of 3 long-chain fatty acids
and glycerol backbone, which are broken down in the process of lipolysis into non-esterified
fatty acids (NEFA) and glycerol (Herdt, 2000). Glycerol can then be converted into glucose
by the liver to be used to restore energy balance while NEFA and glycerol can undergo
lipogenesis to be re-esterified to triglycerides (Makin et al., 2010). The issue with this is that
if there is excessive mobilization of fats that persist in the liver, then fatty liver and liver
dysfunction may occur (Herdt, 2000).
Negative energy balance also allows the stimulation of enzymes in the liver that can
transport NEFA into hepatic mitochondria (Makin et al., 2010). The NEFA can then be
converted to ketones, including β-hydroxybutyrate, which may be used as a source of energy
(Makin et al., 2010). This process can cause an elevated concentration of ketones in the
blood, a state named ketosis, where there will be more ketones than can be used by peripheral
tissues, which may lead to acidosis and toxicity (Barnes et al., 2008) and an altered mental
state leading to additional reduction of appetite in an animal already suffering from
inappetance (Makin et al., 2010). Sheep that are persistently inappetent are more likely to die
of inanition, that is exhaustion of body stores and subsequent circulatory failure, rather than
develop clinical ketosis (Makin et al., 2010). However, the metabolic consequences of
hyperketonaemia or hypoglycaemia in sheep during starvation may be anticipated (Barnes et
al., 2008).
A decrease in feed intake may be seen in animal models in response to acute or
chronic stressors (Bernier, 2006). Bernier (2006) subjected fish to pathological stressors,
such as anorexia, environmental stressors, such as increased water ammonia, physical
stressors including restraint and handling, and social stressors such as isolation and
confinement, and found that they caused a suppression of appetite in fish with corticotrophin-
releasing hormone acting as the primary mediator of the reduction in feed intake.
Cotricotrophin-releasing hormone has also been seen to reduce feed intake in sheep
(Ruckebusch & Malbert, 1986). Corticotrophin-releasing hormone is secreted from the brain
(Krahn et al., 1988) and the gastrointestinal tract (Petrusz, & Merchenthaler, 1992) and is
released into the pituitary portal system that triggers release of ACTH and subsequently
release of cortisol.
As it is known that feeding patterns can be influenced by stress, it would be imperative
18
to understand the duration of abnormal feeding behaviors, especially in the pre-embarkation
feedlots as the effects could carry onto the export ship. One method of measuring feed
behaviour is the use of Radio Frequency Identification (RFID) ear tags on sheep.
1.3.3.1. RFID Tags
Radiofrequency identification (RFID) is a part of the National Livestock Identification
System, where animals are given their own radio frequency identification numbers to allow
tracking of the animal along the supply chain; from the farm property to feedlots, saleyards
and abattoirs, or may also be used on farm to record and collect individual performance of
animals (Pretty & Moroz, 2013). RFID may be used in an ear-tag system, where the tag that
carries the electronic microchip is placed into the ear (Pretty & Moroz, 2013). The tags and
the RFID readers are then able to communicate and transfer information, including individual
identification number (Pretty & Moroz, 2013), between each other using radio waves that can
then be sent to a computer for analysis (Pretty & Moroz, 2013). A limitation on using RFID
technology is the fact that the ear tag must pass within 0.5m of the RFID scanner device and
therefore the animal carrying the RFID ear tag must position itself in such a way that the
electronic earpiece is presented to the RFID reading scanner in an appropriate way (Morris et
al., 2012). Therefore, using RFID technology would make it possible to determine the
feeding behaviour of livestock where RFID antennas are placed along the feed troughs to
allow the scanner to recognize the sheep ear tags when their heads are in such a position that
they are likely to be eating and convey information of how long they are at the feed trough.
Anderson et al. (2014) were able to do this in their experiment to find the drinking
patterns of pigs, in terms of number of visits, intake per unit of time and visit duration, for
disease monitoring. The RFID readers were above the drinking nipple and would record a
positive RFID registration along with use of water, recording every 2 seconds if a transponder
was present or not (Anderson et al., 2014). In this way, RFID ear tag technology would be a
useful measure of feed behaviour as it has the potential to determine whether a stressor would
cause sheep to spend more or less time feeding, and how long the effect of increased or
decreased feeding would extend for.
1.4. Conclusion
Live export in Australia is an industry where large numbers of animals are moved along the
chain, from on-farm where sheep are prepared and selected, to transportation, to the pre-
embarkation feedlot and then loaded onto the live export vessel for the sea voyage (Australia.
19
Department of Agriculture, Fisheries and Forestry., 2011). Shearing is necessary to reduce
the heat load of sheep exported from an Australian winter climate to the summer climate in
the Middle East, with Klemm (1962) determining that shorn sheep were better able to tolerate
hot, humid environments similar to those found on-board the live export vessel. Heat stress in
sheep causes an increase in rectal temperature (Srikandakumar et al., 2003; Phillips &
Santurntun, 2013), respiratory rate, body temperature and water consumption, and a decreased
intake of feed (Monty et al., 1991; Dixon et al., 1999; Beatty et al., 2008;).
Decreases in feed intake are a critical issue for the live export industry, with the
main causes of shipboard death being inanition and Salmonellosis (Norris & Richards,
1989b). There was a high risk of death on live export ship when sheep did not eat pellets late
in the pre-embarkation feedlot period, indicating that mortality on board the sheep was linked
to sheep inappetance late in the feedlot period (Norris et al., 1989c). This indicates that
inanition and changes in feed intake during feedlotting is an important area of the live export
industry that requires more research as any alterations in feeding behaviour during this time
have the capacity to influence the health and mortality of shipped sheep.
Shearing is a necessary pre-embarkation feedlot management procedure that involves
different factors besides removal of wool, including drafting, isolation, restraint,
thermoregulation and human-sheep interaction (Sanger et al., 1989), and the combination of
these factors have been seen to cause stress, in terms of physiological responses including
increased heart rate (Hargreaves & Hutson, 1990c), increased cortisol (Hargreaves & Hutson,
1990a, 1990b, 1990c; Mears et al., 1998; Sanger et al., 2011), increased lymphocytes and
decreased neutrophil counts (Sanger et al., 2011). However, there are limitations of
physiological measures on how they are applied, measure and interpreted (Wickham et al.,
2015) which allow for behavioural measures to be a preferable option in understanding stress
responses in the sheep.
There is a knowledge gap about the effects of shearing on feed behaviour before
embarkation and therefore research is needed in this area of the live export industry. With
this in mind, the aim of future scientific papers should be to determine the behavioural
responses, in terms of feed intake and observed behaviour within the pre-embarkation feedlot.
Behavioural measures of ethograms, and QBA may be used in research as alterations in sheep
behaviour and RFID tags would be useful in understanding feed patterns of sheep over a
period of time. It would be expected that, due to the factors of feed interruption such as
mustering, drafting and yarding that come with the procedure of shearing, there will be a
decrease in feed intake (Makin et al., 2010). However, future research should also understand
20
the duration of any alterations in feed behaviours that may occur as these alterations may be
carried over into the on-board stage of the industry. As the effect of shearing on feed
behaviour is unknown, it would be wise to take a position to expect there to be no relationship
between the two factors.
However, if a relationship between shearing and feeding behaviour is shown,
understanding the association between the two could be the key to ensuring that current
management practices are not disrupting feeding leading to a greater risk of inanition or
Salmonella deaths. In addition, determining which day of shearing of sheep in pre-
embarkation feedlots will allow for the best welfare outcomes in the feedlotting stage of the
live export industry is important.
This project investigates whether day of shearing will affect sheep in terms of feeding
and behaviour in the pre-embarkation feedlot and tests the null hypotheses:
1: There will be no effect of day of shearing on time spent at the feed trough
2: There will be no effect of day of shearing on sheep behaviour
21
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Scientific Report
2.1 Abstract
Sheep entering the live export chain will experience increased handling, novel forms of feed,
and novel environments before the journey on the export ship itself; all occurring over a
period of around one month (Norris et al., 1989a). These factors can also cause stress
(Kilgour & DeLangen, 1970; Hargreaves & Hutson, 1990a, 1990b; Doyle et al., 2010; Sanger
et al., 2011), which could lead to a high incidence of inappetance and mortality (Norris &
Richards, 1989b; Higgs et al., 1993). This study was conducted to determine whether the day
of shearing could affect feeding and behaviour of sheep in the pre-embarkation period.
Sheep were fitted with Radio Frequency Identification (RFID) tags that could be
picked up by tracking antennae at all water and feed troughs in the pens when the sheep’s
head was in such a position that the sheep was likely to be eating or drinking. The system
then would record the total amount of time the sheep spent at the troughs per day. The sheep
were shorn on either day 1, 2, 3, 4 or 5 and an ethogram was generated through analysis of
60-second video clips from footage of the sheep filmed one hour after shearing.
There was no difference in time spent at feed troughs between any treatment groups
on any day. There was a treatment effect, with the control (unshorn) group spending more
time at the water trough; however, there were no difference between the other groups in time
spent at water troughs or any behavioural states or events.
The results suggest that shearing may occur on any day during the pre-embarkation
feedlot period, and that current management practices do not disrupt time spent at the feed
trough.
37
2.2 Introduction
The live export of sheep plays an important role in Australia’s economy. Australia exported
20 million head of live sheep in 2013-2014; 97% were exported to the Middle East (MLA,
2015). Sheep shipped to the Middle East may undergo exposure to contrasting environments,
from an Australian winter to a summer in the Middle East. Temperatures have been noted to
reach up to 35°C dry bulb on some locations on the export ship (Bailey & Fortune, 1992), and
large heat loads on sheep have been shown to cause increased respiratory rate, body
temperature, and water consumption, as well as decreased feed intake (Monty et al., 1991;
Dixon et al., 1999; Beatty et al., 2008). In order to limit excessive heat loads of the sheep,
regulations require that sheep sourced for live export have been shorn recently prior to
loading onto the live export vessel; regulations also consider timing of that shearing and there
is a requirement for freshly shorn sheep to be protected in sheds if they are to be shorn very
soon before shipping. That is, sheep exported to the Middle East must have wool not longer
than 25mm in length, be less than 10 days since shearing, or if they are to be shorn during the
10 day period before shipping, this must occur while the animals are accommodated in sheds
on registered premises (Australia. Department of Agriculture, Fisheries and Forestry, 2011).
Shearing primarily involves the act of wool removal; however, other aspects of the
procedure contribute to sheep stress, including being yarded, moved along a race, penned,
caught, upended, and then dragged to the shearing station to be shorn (Devlin et al., 1989), as
well as the noise and vibration of the shearing hand-piece and risk of skin injury (Sanger et
al., 2011). The combination of these factors have been seen to cause stress in terms of
physiological responses, including increased heart rate (Hargreaves & Hutson, 1990c),
increased cortisol (Hargreaves & Hutson, 1990a, 1990b, 1990c; Mears et al., 1998; Sanger et
al., 2011), increased lymphocytes, and decreased neutrophil counts (Sanger et al., 2011).
The effect of day of the shearing procedure on feeding behaviour has not been
previously studied. Sheep entering the live export chain will have experienced increased
handling, road transportation, vaccinations, drafting, shearing, altered diets, novel forms of
feed, and novel environments before the journey on the export ship itself; all occurring over a
period of around one month (Norris et al., 1989a). These factors can cause stress in sheep
(Kilgour & DeLangen, 1970; Hargreaves & Hutson, 1990a, 1990b; Doyle et al., 2010; Sanger
et al., 2011), which can result in decreased feed intake and inanition leading to mortality
(Norris & Richards, 1989b; Higgs et al., 1993).
Feeding behaviour is extremely important in the live export process as inanition and
salmonellosis being identified as two main causes of death in the live sheep export industry
38
(Norris & Richards, 1989b; Richard et al., 1989). There is a high risk of death on the ship
when sheep do not eat pellets late in the pre-embarkation feedlot period, suggesting that
mortality on board the ship is linked to sheep inappetance late in the feedlot period (Norris et
al., 1989c). This study therefore aims to determine whether the day of shearing while in the
pre-embarkation feedlot influences sheep behaviour, specifically posture, locomotion activity
and rumination, as well as the time spent at the feed and water troughs. Changes in
locomotion activity of the sheep can be interpreted in several ways, with studies by Molony &
Kent (1993) finding that an increase in locomotion in terms of pacing and restlessness, due to
castration and tail-docking, could be used as an indicator of pain and discomfort. Increased
locomotion could also reflect fear (Romeyer & Bouissou 1992; Vandenheede et al 1998) or
nervous agitation, which can be an indicator of ‘stress’ (Baldock & Sibly, 1990; Cockram et
al., 2004; Wemelsfelder & Farish, 2004). Understanding any association between the day of
shearing, feeding patterns and behavioural responses may indicate where sheep incur stress,
and where the welfare risks are highest, and could assist in promoting management practices
that reduce the incidence of abnormal feeding. The null hypotheses being tested in this study
are that there will be no difference in time spent at the feed and water trough between sheep
shorn on different days, and no difference in observed behaviour between sheep shorn on
different days.
3. Materials and Methods
All experimental procedures were reviewed and approved by the Animal Ethics Committee at
Murdoch University (Permit number R2598/13).
3.1 Animals
A total of 600 Merino wethers (born in 2014) were sourced from a property in Cranbrook,
Western Australia. The wethers had last been shorn in January of 2015. The sheep were
moved from the farm and arrived on the 22/7/2015 at approximately 18:30h, travelling for
approximately 300 km.
3.1.1 Location and Housing
Sheep were housed in an intensive Australian Quarantine and Inspection Service (AQIS)
accredited pre-embarkation feedlot, approximately 30 km south of Perth, Western Australia.
The feedlot has elevated sheds that can accommodate approximately 80,000 sheep, with an
additional 20,000 sheep held in the paddocks. These sheds operate using a 24-hour, fully
39
automated feed and water system providing ad libitum feed and water. Within each shed are
eight pens separated by metal fencing and gates, with mesh floor supported by wooden
beams. The outer walls and roof are made of corrugated metal with the outer walls enclosed
to a height of 0.7 m with additional 2.5m open to the roof. The pens are approximately 10 x
25 m with six feed troughs and three water troughs per pen (Figure 3.1). The sheep in this
experiment were held in two adjacent pens, Pen 3 and 4, of the southern side of one shed for
13 days (23/07/15-6/08/15).
Figure 3.1. Merino sheep in the elevated feedlot shed containing feed and water troughs.
3.1.2 Environmental Measures
The ambient dry bulb temperature (°C) and relative humidity (%) in the feedlot shed during
the duration of this experiment was recorded using 5 data loggers (Onset HOBO H8 Pros,
#H08-032-IS, OneTemp Pty Ltd, Australia) positioned on the outside edge of the feedlot shed
pens. These data loggers were programmed to record the conditions every 2 seconds.
3.2 Identification
On arrival at the feedlot, all 600 sheep were kept together in the shed overnight. The
following morning, the sheep were randomly separated into two pen groups (n= 300) and
within these two groups they were further separated into six shearing day treatment groups,
with 50 sheep per treatment group per pen (Table 3.1). The animals were passed through a
Water
Trough
Feed Trough
40
race where they were each had a Radio Frequency Identification (RFID) Tag (Allflex Open
Cup reusable) inserted into its right ear (Figure 3.2). The RFID tag was a standard passive
134.2kHz half duplex National Livestock Identification Scheme (NLIS) tag containing a
microchip that can be read by an electronic RFID reader. After insertion of the RFID ear tag,
an ALEIS Reader Model 8030 One-Piece portable wand recorded the ear tag number, and the
data was uploaded onto an electronic tracking program to be used for identification of sheep
at the water and feed troughs. A coloured 54 x 48 mm ear tag (Leader Flexible Tag Size 2 -
Female) was inserted into the left ear, serving as identification of the treatment groups (Table
3.1).
Figure 3.2. Radio Frequency Identification Tag inserted in the right ear of a Merino sheep (a)
and portable wand to record the ear tag number (b).
a)
b)
41
Table 3.1. The colour of the ear tag that corresponds to the day the sheep is shorn.
Colour of Ear Tag Day Shorn
Red Control (Unshorn)
Orange 1
Green 2
Blue 3
Pink 4
Yellow 5
3.2.1 Feed and Water Measurements
Each feed and water trough was fitted with tracking antennae by removing the sloping metal
wall for the trough above the area holding the feed/water and multiple banks of antennae
installed with connections to a central computer. The antennae pulse at millisecond intervals
to detect the presence of the individual RFID tags when a sheep approached the trough within
350mm (Figure 3.3), thereby detecting when their heads were in such a position that they
were likely to be eating or drinking. The tags and antennae work as an exclusion system; the
non-detection of an RFID tag means that the animal was not at the feed or water troughs,
however the presence of the tag could not definitely mean that the animal was drinking or
eating (Barnes et al., 2013).
The RFID data were analysed for the number of visits (events) at the feed and water troughs
and the total amount of time at the troughs per day by each individual. For the purposes of
analysis, each day ran from 13:00h-12:59h. Feed troughs were checked daily to ensure silos
were full.
42
Figure 3.3 Antennae installed throughout the feed troughs.
3.3 Shearing
Five hundred sheep were shorn during the duration of this experiment; 100 sheep on each of
five consecutive days (Table 3.1). The 100 control sheep were not shorn at all and assigned
as the control group. Sheep were drafted at midday each day, and sheep that were to be shorn
the following day moved to the shearing shed, where feed and water was withdrawn overnight
(Figure 3.4). Sheep were shorn in the morning and returned to the mob at 13:00h the same
day. Although no sheep were to be shorn the following day, on day 5, all sheep were still
taken out of the feedlot shed and run through the sheep race to await the return of the shorn
sheep so that all sheep had been handled similarly on each treatment day.
Two shearers were present to shear 100 sheep at a rate of approximately 2.4 min per
sheep, and the same shearers shore all sheep in this study.
43
Figure 3.4. The timetable for shearing and filming sheep. (* On Day 13 all sheep were filmed
at midday)
3.4 Body Condition Scores
While sheep were held in the race, the body condition score (BCS) of each individual was
assessed by palpation using the tips of fingers and thumb, on and around the lumbar spine, in
the loin area behind the last rib, in order to score sharpness or roundness of the spinous
processes, the degree of fat cover over and below the transverse processes, and the fat cover
in the angle between the transverse and spinous process (Russel, 1984). A BCS of 1 was
assigned to animals with very little fat and muscle coverage, and BCS 5, to animals with
plenty of coverage, creating more difficulty in feeling the short ribs (Australia. Department of
Agriculture and Food., 2015). The BCS was assessed to the nearest 0.5.
3.5 Filming
The sheep were filmed as a group each day for the first 6 days (days 0, 3, 4, 5, and 6) and
again on the last day of this study (day 13). No sheep were shorn on day 6 and day 13;
however, to simulate similar handling conditions on each day, all sheep were taken out of the
feedlot shed to be run through the race once and held in the yards for approximately 1 hour on
day 6 and 13, before being moved back into the feedlot shed to be filmed. On conclusion of
the study, on day 13, after being filmed the animals were passed back through the race and
scored for BCS. The RFID and coloured ear tags were removed by cutting the stem of the tag
after confirming RFID and group.
For filming, eight digital camcorders (2 x Panasonic HC-V520M, 4 x Panasonic SDR-
H280, 2 x Go Pro Hero 3) were mounted on portable tripods approximately 1.4 m above
ground, attached to the corner of each pen, with four cameras per pen. These cameras faced
44
towards the middle of the pen (Figure 3.6). The same researcher turned on all cameras and
left the yard, so that the sheep were recorded undisturbed for 1 hour in the afternoon after the
sheep had returned to their respective pens (approximately 1 hour after shearing).
The 60-second clips were selected from the footage 20-30 min after cameras were
turned on to allow for the animals to recover from the disturbance of the researcher being
present to turn on the cameras. A 60 s timeframe was the maximum time that the sheep
generally stayed in focus in the camera frame, before either walking out of frame or being
obscured by another sheep. Over this interval, at least 10 individual focal sheep of each
treatment group, identified by their coloured ear tag, were analysed using footage available
across all the cameras.
Figure 3.6. The cameras used to record the sheep angled towards the middle of the pen.
3.5.1 Behavioural Ethograms
A behavioural ethogram was modified from Lauber et al. (2012) and McClelland (1991).
The ethogram contained three mutually-exclusive states and 21 events to describe the
behaviour the sheep demonstrated (Table 3.2). The three states were walking, standing, and
lying, describing the activity of the animal. The duration of the states was presented as a
proportion (%) of time for the 60-s clip. The events were counts of the occurrence of quick
actions that occurred for <5 s.
45
Table 3.2. Behavioural categories used in ethogram.
States (% of time)
Walking Moving around in pen, not standing stationary
Standing Standing stationary on four legs
Lying Lying on floor
Events (counts)
Being Pushed Head Being pushed by another sheep’s head
Being Pushed Body Being pushed by another sheep’s body
Being pawed by another sheep Being pawed by another sheep
Body shake Whole body shake
Chew Pen fixtures Chewing pen fixtures (floor slats, wire,
palings, feeder)
Head-butting Aggressor hits another sheep with head
without first backing up
Head Down Head lowered below shoulders
Head Up Head above shoulders
Move mouth parts Curling of the upper lip (Flehmen response)
Nosing Pen fixtures Nosing or rubbing muzzle of pen fixtures
Pawing another sheep Striking another sheep with forelegs
Pawing Ground Striking ground with forelegs
Pushing Head Pushing another sheep using its head
Pushing Body Pushing another sheep using its body
Ruminating Chewing cud
Smelling Inhale odour of the environment through nose
Smelling another sheep Inhale odour of another sheep through nose
Sneezing Expulsion of air from the nose/mouth
Tongue Movements Licking himself (front legs, shoulders, hind
legs, rump, underside)
Vocalisation Producing sounds with mouth
46
3.6 Statistical Analysis
A Mixed-Model ANOVA (Statistica, StatSoft-Inc, 2001) was used to identify whether there
were significant shearing treatment differences (independent factor) and pen effects (random
factor) on the proportion of time sheep spent walking, standing, or lying (three separate
dependent measures). As the sheep spent very little time walking, only standing and lying
were further analysed. The time spent standing and lying data were log-transformed and were
tested for normality (Shapiro-Wilk test), however the data did not meet the assumption of a
normal distribution. The frequency of occurrence for individual events from table 3.2 was too
low for data analysis.
A Mixed Model ANOVA was used to analyse any significant difference between
treatment groups and pens, and the behavioural events listed in Table 3.2. The dependent
variables used were each behavioural event (Table 3.2), the fixed variables were treatment
and day, and the random variable was pen.
The time spent at the feed and water trough for each sheep was analysed using a
Mixed-Model ANOVA (Statistica, StatSoft-Inc, 2001), which allowed for a repeated-
measures approach that catered for the missing data when animals were removed for shearing.
The dependent variable used was time at feed trough, and the fixed variables were whether
the sheep were shorn or not, and day. The individual ID and pen were included as random
variables. The time spent at feed and water trough was tested for normality (Shapiro-Wilk
test) and did not meet the assumption of a normal distribution.
A mixed model ANOVA (Statistica, StatSoft-Inc, 2001) was done to analyse any
significant differences in total time at feed trough and the difference in BCS from the start to
the end of the study. The BCS difference was used as the dependent variable, the random
factor was pen, the fixed factor was treatment and the covariate was total time at feed trough.
47
4. Results
The feed and water trough antennae worked throughout the duration of the experiment, but
one RFID tag from each of the orange, yellow and blue tagged groups had no recorded
information on the feed and water trough attendance, and were detected as not working at the
time of removal. All sheep were in good health except one red tag and one orange tag sheep
that appeared to be lame and these were removed from the experiment. One yellow tag sheep
had jumped a fence and mixed with another pen of non-experimental sheep and was removed
in this experiment. Altogether, 594 sheep were used for analysis.
4.1 Environmental Conditions
The mean dry bulb temperature over the duration of 13 days in this study was 13.4°C ± 2.7
(min 8.5°C; max 16.7°C). The mean humidity was 78.4% ± 8.9 (min 67.6%; max 93.9%)
over the study (Figure 4.1).
Figure 4.1 Mean dry bulb temperature and relative humidity throughout the 13 days.
4.2 Time Spent at the Feed Troughs
As seen in Figure 4.1, there was a trend for all sheep to increase their total mean time per day
at the trough over the duration of the study. Statistically, there was no difference in mean
daily feed time between treatment groups (Table 4.1). However, on day 5 there was a
0
10
20
30
40
50
60
70
80
90
100
0
5
10
15
20
25
0 1 2 3 4 5 6 7 8 9 10 11 12 13
Re
lati
ve
Hu
md
ity
(%
)
Te
mp
era
ture
(°C
)
Day
Temperature and Relative Humidity
Temperature
Relative Humidity
48
significant time x day interaction, with an increase in mean total time spent at the feed trough
for all treatment groups (F 5, 55= 2.78, p<0.001) (Table 4.1).
Figure 4.2. Mean total time sheep spent at the feed trough.
Table 4.1. Time spent at feed trough. Bold indicates statistical significance.
ANOVA Results for Synthesized Errors: Time spent at Feed
trough
Df Error computed using Satterthwaite method
*Tests assume that entangled fixed effects are 0
d.f. F P
Animal ID 1,5 0.037 0.854
Treatment 5,6 1.35 0.357
Day 12,12 41.96 <0.001
Pen 1,9 0.968 0.350
Treatment*Day 55,55 2.78 <0.001
Treatment*Pen 5,60 4.42 0.002
Day*Pen 12,55 3.38 <0.001
Treatment*Day*Pen 55, 7080 0.496 0.999
1:33:36 AM
1:48:00 AM
2:02:24 AM
2:16:48 AM
2:31:12 AM
2:45:36 AM
3:00:00 AM
3:14:24 AM
3:28:48 AM
3:43:12 AM
0 1 2 3 4 5 6 7 8 9 10 11 12
Tim
e (
h:m
m:s
s)
Day
Unshorn Shorn Day 1 Shorn Day 2
Shorn Day 3 Shorn Day 4 Shorn Day 5
49
Using the recorded data to add up the total time per day at the feed trough, those sheep
that attended the feed trough for less than 30 min total per day were identified. More sheep
spent less than 30 min at the feed trough on day 1, and by day 4, most sheep were attending
the feed troughs for more than 30 min (Figure 4.3).
Figure 4.3. Number of sheep spending less than 30 min at the feed trough
4.3 Time Spent at the Water Troughs
There was no difference in time spent at the water trough per day between the shorn treatment
groups (F 5,5 = 8.63, p = 0.017) (Figure 4.4). Only the control (unshorn, red tag) sheep had a
treatment x day interaction (F 55, 55 = 3.98, p<0.01) where they spent significantly more time
at the water trough than other groups on days 4–12 (Table 4.2).
0
5
10
15
20
25
0 1 2 3 4 5 6 7 8 9 10 11 12
Nu
mb
er
of
Sh
ee
p
Day
Unshorn Shorn Day 1 Shorn Day 2
Shorn Day 3 Shorn Day 4 Shorn Day 5
50
Figure 4.4. The mean total time sheep spent at water trough.
Table 4.2. Time spent at water trough. Bold indicates statistical significance.
12:07:12 AM
12:10:05 AM
12:12:58 AM
12:15:50 AM
12:18:43 AM
12:21:36 AM
12:24:29 AM
12:27:22 AM
12:30:14 AM
12:33:07 AM
0 1 2 3 4 5 6 7 8 9 10 11 12
Tim
e (
h:m
m:s
s)
Day
Unshorn Shorn Day 1 Shorn Day 2
Shorn Day 3 Shorn Day 4 Shorn Day 5
ANOVA Results for Synthesized Errors: Time spent
at Water trough
Df Error computed using Satterthwaite method
*Tests assume that entangled fixed effects are 0
d.f. F P
Treatment 5,5 8.628 0.017
Day 12,12 19.0 <0.001
Pen 10,5 0.718 0.437
Treatment*Day 55,55 3.99 <0.001
Treatment*Pen 5,56 5.58 <0.001
Day*Pen 12,55 0.885 0.567
Treatment*Day*Pe
n 55, 7081 0.599 0.992
51
4.4 Body Condition Score
There was no statistical difference in BCS differences from entry and exit and the total time
spent at feed trough between any treatment groups (p>0.05) (Figure 4.5).
Figure 4.5. Body condition score on entry, exit and the difference between them between
treatment groups.
4.5 Behavioural Ethograms
The results of the behavioural ethograms for standing, lying and walking are shown in Figure
4.5. There was no pen effect and therefore the pens were combined for each treatment group.
There was no treatment effects for proportion of time spent walking. There was a day effect
for standing (F 5,5=6.63 p = 0.029) (Table 3.6) and a time x day interaction for lying (F 23, 23=2.48,
p = 0.017) (Table 4.3), where all treatment groups spent more time standing and less time
lying from day 0 to day 13. However, it can be seen that the control (unshorn) group spent
more time lying and stood less on day 6 (Figure 4.4).
0.0
0.5
1.0
1.5
2.0
2.5
3.0
Unshorn Shorn Day1
Shorn Day2
Shorn Day3
Shorn Day4
Shorn Day5
Bo
dy
Co
nd
itio
n S
core
Treatment Group
BCS entry
BCS exit
BCS difference
52
Table 4.3. Proportion of time spent standing in a 60s clip. Bold indicates statistical
significance.
Table 4.4. Proportion of time spent lying in a 60s clip. Bold indicates statistical significance.
ANOVA Results for Synthesized Errors: Standing
Df Error computed using Satterthwaite method
*Tests assume that entangled fixed effects are 0
d.f. F P
Treatment 5,5 1.37 0.370
Day 5,5 6.63 0.029
Pen 1,6 0.03 0.864
Treatment*Day 23, 23 1.81 0.082
Treatment*Pen 5,24 2.48 0.06
Day*Pen 5, 23 2.76 0.043
Treatment*Day*Pen 23, 653 0.968 0.505
ANOVA Results for Synthesized Errors: Lying
Df Error computed using Satterthwaite method
*Tests assume that entangled fixed effects are 0
d.f. F P
Treatment 5,5 1.35 0.374
Day 5, 5 5.79 0.039
Pen 1, 7 0.006 0.938
Treatment*Day 23, 23 2.48 0.017
Treatment*Pen 5, 24 2.48 0.06
Day*Pen 5, 23 3.39 0.019
Treatment*Day*Pen 5, 653 0.804 0.728
53
Figure 4.6. Percentage of time the sheep spent lying, standing and walking on day 0 (a), day 3
(b), day 4 (c), day 5 (d), day 6 (e), and day 13 (f) for the treatment groups of unshorn sheep
(US), sheep shorn day 1 (D1), sheep shorn day 2 (D2), sheep shorn day 3 (D3), sheep shorn
day 4 (D4), and sheep shorn day 5 (D5).
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
US D1 D2 D3 D4 D5
Pe
rce
nta
ge
of
Tim
e (
%)
Lying
Standing
Walking
a)
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
US D1 D2 D3 D4 D5
Pe
rcn
eta
ge
of
Tim
e (
%)
Lying
Standing
Walking
c)
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
US D1 D2 D3 D4 D5
Pe
rce
nta
ge
of
Tim
e (
%)
Lying
Standing
Walking
d)
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
US D1 D2 D3 D4 D5
Pe
rce
nta
ge
of
Tim
e (
%)
Lying
Standing
Walking
e)
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
US D1 D2 D3 D4 D5
Pe
rce
nta
ge
of
Tim
e (
%)
Lying
Standing
Walking
f)
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
US D1 D2 D3 D4 D5
Pe
rcn
eta
ge
of
Tim
e (
%)
Lying
Standing
Walking
b)
54
Several other behavioural events were recorded, including head butting, pawing
ground, head down, rumination and vocalisation (Table 3.2). There was no treatment effect
for any event (P>0.05).
55
5. Discussion
It was found that there was no difference between treatment groups in terms of the time sheep
spent at the feed trough, the water trough or in behaviour due to day of shearing and thus the
null hypotheses are retained.
5.1 Time Spent at the Feed Troughs
There was no significant difference in total feeding time per day between treatment groups on
any day. Therefore, our null hypothesis that there would be no difference in total feed time
due to shearing was retained. This indicates that day of shearing had no significant effect on
the time sheep spent at the feed trough.
While the effect of the shearing procedure on sheep and feedlot feed intake has been
studied, these two factors have not been studied together and their correlation is unknown.
An example of this is that shearing has been seen to increase dry organic matter (DMO)
intakes by 42-62% in grazing sheep (Wheeler et al., 1962); however, the environmental
conditions contrast those in our experiment where their sheep were in a paddock and had not
undergone all the procedures that sheep experienced as a part of the live export chain
including increased handling, road transportation, vaccinations, drafting, altered diets, novel
forms of feed and novel environments (Norris et al., 1989a). Wheeler et al. (1962) postulated
that the cold the sheep experienced after shearing influenced the increase in DMO intake of
sheep. This compares to the temperature of our experiment, with a minimum of 8.5°C to a
maximum of 16.7°C, where we showed no difference between shorn and fleeced treatment
groups in terms of time at feed trough.
Shearing has been seen to cause physiological stress, with increased heart rate
(Hargreaves & Hutson, 1990c), increased cortisol (Hargreaves & Hutson, 1990a, 1990b,
1990c; Mears et al., 1998; Sanger et al., 2011), increased lymphocytes and decreased
neutrophil counts (Sanger et al., 2011). Therefore, it could be expected that sheep that were
shorn only one day after arrival to the feedlot may have decreased the time spent feeding,
because these sheep would have had the shortest amount of time to rest from any stressors
caused by transportation (Smith et al., 2004), and adaption to the novel environments and new
pelletised feed (Chapple & Wodzicka-Tomaszewska, 1987; Norris et al., 1989a), compared to
our control (unshorn) and sheep shorn on day 5. However, there was no difference in time
spent at feed troughs on any day between shorn and unshorn sheep.
56
Beatty et al. (2008) also found no differences in feed intakes between fleeced and
shorn sheep where shorn and fleeced sheep were kept in climate control rooms under
thermoneutral conditions compared to hot and humid environmental conditions. The
environmentally hot and humid conditions found in the Beatty et al. (2008) study contrasted
to the conditions present in our study; however, neither study found a difference in feeding
behaviour between shorn and unshorn sheep in terms of feed intake or time spent at the feed
trough, which supports the idea that shearing does not affect feeding behaviour. It has been
found that there is a high risk of death on the live export ship when the sheep did not eat
pellets late in the pre-embarkation feedlot period, indicating that mortality on board the ship
was linked to sheep inappetance late in the feedlot period (Norris et al., 1989c). Our
experiment indicates that shearing did not appear to be a contributing factor to sheep
inappetance, under our conditions, during the pre-embarkation phase of live export, and
therefore shearing may occur on any day in the feedlot.
In the live export industry, sheep must adapt to a novel pelletised feed diet that is
found aboard the live export vessel (Norris et al., 1990), and it has been identified that there
are some sheep that do not adapt to the novel feed during the pre-embarkation feedlot and
voluntarily refuse to eat, with these sheep termed ‘shy feeders’ (Syme & Elphick, 1986). For
this experiment the percentage of sheep attending the feed trough for a total of less than 30
min each day was calculated, as 30 min was the minimum total time previously determined to
indicate adequate feed trough attendance (Barnes et al., 2013). These results corresponded
with those of Barnes et al. (2013), with some sheep spending 30 min or less at the feed trough
on day 1 and day 2, and by day 4, most sheep were attending the feed troughs for more than
30 min, with no effect of shearing.
There was no treatment effect on the time spent at the feed trough; however, there was
a time x day interaction where, on day 5, all groups significantly increased their total mean
time at the feed trough. The reason for the increase in total feed time on day 5 is unknown,
with the feed troughs being checked daily to ensure that the sheep were not without feed
overnight as well as there being no major environmental events such as sudden changes in the
temperature that could cause this increased time at the feed trough for all treatment groups. It
can be speculated that perhaps the silos had been refilled on day 5 and therefore the sheep
consumed more pellets compared to the day before, due to the increased amount of pellets
available. It could also be possible that a disturbance during the night may have caused the
sheep to become more active with less sleep and thus had a higher need for feeding the next
day. This is possible as the sheep shed was adjacent to the sheep receival area for the feedlot
57
and therefore a possible disturbance during the night could be the receival or loading of other
sheep from a transport vehicle. Whilst this increase of time at feed trough is statistically
significant, it can be postulated that this is biologically not significant.
It must be noted that this study does not determine the amount of feed the sheep
consumed after being shorn, but does indicate that shearing on a particular day will not
significantly affect the total time at the feed trough.
5.2 Time Spent at the Water Troughs
There was only one treatment effect with the control (unshorn) sheep spending more time at
the water trough. However, there was no significant difference in total drinking time between
the shorn sheep indicating that the day of shearing had no significant effect on the sheep’s
time at the water trough
The control (unshorn) sheep had a time x day interaction where they spent more time
at the water trough from day 4 onwards (p<0.001) compared to the other treatment groups.
This is most likely due to the fact that the control sheep retained their fleece for the duration
of this experiment. Water intake comparison between shorn and fleeced sheep has been
studied before by Beatty et al. (2008) who found that fleeced sheep had higher respiratory
rates and water intakes, possibly reflecting the use of respiratory water loss via panting for
evaporative cooling. It was found that fleeced sheep with a wool length of 10.6 cm would
ingest approximately only 15% more water compared to the shorn sheep at 15°C, with longer
wool increasing water intake by fleeced sheep compared to shorn sheep (Al-Ramamneh et al.,
2011). The sheep in the present study had 6 months of wool cover, approximately 4.5 cm
long, with the temperature at an average of 13.4°C, which could explain why the fleeced
sheep spent an average of 9 min more at the water trough after day 4 where the majority of
sheep had been shorn by that point.
5.3 Body Condition Score
In this study, there was no statistical difference between total time at feed trough, and BCS
differences between any treatment groups (p>0.05) (Figure 4.5). The benefit of utilizing BCS
is that it gives an indication of body reserves of the sheep without results being confounded
by frame size (Brown et al., 2015) or the influence of wet wool and wool growth on
liveweight (Western Australia. Department of Agriculture and Food., 2015). However, it may
be noted that the duration of this study could be too short a time to allow for variations in
BCS to be detected. One possible way of understanding whether the sheep had a higher
58
intake of feed would be to measure individual feed intake or weight. However, it is difficult
to measure individual feed intake at the feedlot, because all the sheep run together; having
individual pens would make it a very different system to the commercial set up which was
being assessed.
5.4 Behavioural Ethograms
This study determined that there was no significant difference between groups in behaviour
the sheep exhibited. Therefore, our null hypothesis that there would be no difference in
behaviour was retained. However, there was a treatment x day interaction for standing
(p<0.05) and lying (p<0.05), where all treatment groups spent more time standing than lying
by day 13 compared to day 0. Sheep that are considered to be ‘calm’ generally lie down
ventrally with their legs tucked under (Wemelsfelder & Farish, 2004). Rather than thinking
that the sheep were less calm throughout the experiment, another possible reason for why the
sheep laid down more on day 0 could be that the sheep were tired as they had stood in the
transport vehicle from farm of origin to the feedlot.
Transport involves introducing animals to novel, noisy environments with food and
water restriction, transport motion, mixing of animals, periods of confinement, crowding,
vibration, loading and unloading, and has the potential to be a stressor for livestock (Swanson
& Morrow-Tesch, 2001). The behavioural response to transport has been investigated, with
Cockram et al. (1996) finding that in a 12-hour journey, sheep would lie down if given
sufficient space, and Bradshaw et al. (1996) finding that sheep would continue to stand
regardless of available space. Transport has also been seen to incur the greatest effect on
sheep behaviour if sheep were directly transported from pasture, and these sheep would lie
down less during transportation compared to those transported from pens (Cockram et al.,
2000). Therefore, when arriving at the feedlot the sheep might choose to lie more on day 0 in
order to rest, and then would stand more once they had recovered, as the length of stay
increased. It was not until day 13 where the majority of sheep were standing; however, the
sheep were not filmed from day 7-12 and therefore it could be one of these days where almost
all sheep initially began standing.
Another reason for sheep standing more throughout the duration of the study could be
due to confinements of the pen. Merino sheep on farm paddocks generally have a large area
of land for them to walk through to find feed and water. During this study, sheep were in
pens of 10 x 25 m with two hundred other sheep, and with six feed troughs and three water
troughs readily available. Therefore, the sheep did not have to walk to find feed and water
59
and, once they had recovered from the road transportation, perhaps they had a greater
tendency for standing due to lack of space or options for them to perform other natural
behaviours, e.g. grazing. Immobilisation has also been shown as a parameter of both docility
and absence of fear, or nervousness or fear (Romeyer & Bouissou, 1992; Vandenheede et al.,
1998; Cockram, 2004). In this study the sheep were not seen to have a ‘tense, frozen’ posture
reflected in nervous or fear induced immobilisation (Wemelsfelder & Farish, 2004); however,
due to the subjective nature of observed behaviour, it cannot be completely ruled out. Future
studies may chose to overcome the subjective nature by creating more defined ethograms and
states, for example describing in more detail how the sheep walked, stood, or lay
Increased locomotion activity has been used as a parameter of fear in livestock
(Romeyer & Bouissou, 1992; Mounier et al., 2006) or for sheep exploring their surroundings
(Wemelsfelder & Farish, 2004), and could be speculated that when the sheep arrived at the
feedlot or after shearing there would be an increase in locomotion; however, this was not the
case in this present study where there was very little time spent walking.
On day 6, the control (unshorn) group laid down more and stood less (p<0.05)
compared to the other treatment groups. Studies in cattle have shown that increasing
temperatures and heat stress cause a reduction in lying behaviour and an increase in standing
behaviour (Igono et al., 1987; Overton et al., 2002), because standing maximises evaporative
cooling mechanisms from body surfaces, and benefits from the convection due to wind (Igono
et al., 1987). Due to the temperatures of this study, with a minimum of 8.5°C to a maximum
of 16.7°C, it is unlikely that the lying down behaviour for the control (unshorn) sheep was
due to heat stress. It can be postulated that it may be because by day 6 all other sheep had
been shorn and the control sheep were the only ones that had not been feed/water restricted
and still had their full fleece. Having not undergone shearing, these sheep may have been
‘calm’ compared to all other groups that had been drafted, penned and isolated, feed/water
deprived, shorn with risk of skin injury, and then returned to the pen the following day, all of
which has been seen to cause stress in the sheep (Kilgour & DeLangen 1970; Syme &
Elphick, 1982; Hargreaves & Hutson, 1990a, 1990b, 1990c; Sanger et al., 2011).
5.5 Limitations
In retrospect, the observed behaviour of this study only focused on 20 individuals from
treatment groups of 100, and therefore this small sample size has the potential to skew the
results compared to if these states and events where studied with a greater sample size. This
study focused on a 10-min window of time after shearing, and therefore it could be expected
60
if this study was filmed and behaviour analysed over the course of a day for the 13 days, more
subtle changes in behaviour may have been found. Also, the sheep clips were primarily taken
only from one corner of the pen, with sheep constantly walking out of frame before 60
seconds, which made it difficult to ensure that the sheep that walked back into frame was the
same sheep that had already been counted. Future studies may consider the use of digital
pedometers to recognise whether individual sheep are at rest or are walking per day for a
more accurate result. For example, Champion et al. (1997) used sensors that incorporated
mercury tilt switches, which could measure lying, standing, and walking behaviour of cattle
and sheep, which would be useful in obtaining more information on the different states the
sheep perform before and after shearing.
It must also be taken into account that only one line of sheep, all from the same farm,
was used in this study. Social mixing has been seen to disrupt social structures (Sevi et al.,
2001; Mounier et al., 2008) and influence behavioural responses in sheep (Miranda-de la
Lama et al., 2012), and therefore these results may be skewed due to the performance of this
one group of sheep. Future studies may endeavour to use different lines of sheep from
different farms to allow for social mixing and individuality. Another future study may also
explore if day of shearing could cause sheep to become more susceptible to Salmonella
organisms, and therefore contribute to inanition in the live export chain in this way.
6. General Conclusions
This study examined the effect of day of shearing on the time spent at the feed and water
trough as well as the effect on observed behaviour. Sheep were randomly allocated days 1-6
to be shorn, and RFID tags were used to record the total time spent at the feed and water
troughs. There was no difference in time spent at the feed and water troughs for sheep shorn
on any day, and therefore the null hypothesis is retained. The results also found that there was
no difference in observed behaviour, and therefore the null hypothesis is retained.
The main causes of shipboard death of sheep are inanition and salmonellosis (Norris
& Richards, 1989b). In this study, shearing did not appear to be a contributing factor to sheep
inappetance under these conditions. However, future studies should endeavour to overcome
the limitations of this experiment to verify these findings. It can be concluded, that for this
group of sheep, shearing could occur on any day that the sheep were at the pre-embarkation
feedlot and that current management practices did not disrupt feeding behaviour, that is, the
amount of time the sheep will spend at the feed and water trough, and observed behaviour.
61
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