What is end-of-lay?

Laying hens are transported 3 times in their life: from the hatchery they are transported as day-old chicks to the rearing house. At 17-18 weeks of age they are transported from the rearing house to the layer house. At the end of the laying period, they are transported to the slaughter house. This last transport needs to be managed well to prevent animal welfare problems.
End of lay addresses this last transport, from the moment of catching until the moment of slaughter. Also some management measures taken to prepare the birds for transport are taken into account in the trajectory indicated as end of lay.

In detail the following measures and periods can be identified (see also figure):

On farm:

• Withdrawal from food: usually the morning before depopulation the food is withdrawn from the birds to make sure they will have their intestines empty when transported
• Catching: A special crew catches the birds to take them out of their housing system. Usually this is done in the dark, so hens don’t fly away. The resting birds can easily being taken from the perches.
• Carrying to the crates or modules : if the crates are brought into the henhouse, the distance is very short. Otherwise the birds are carried out of the house to the place where the modules or crates are located. This can be in the service area of the house or on the truck.
• After each truck is loaded, it will leave towards the slaughter house.

On the road:

• Depending on the distance the transport will have a longer or shorter duration and may require a resting period

At the slaughter house:

• At the slaughter house the crates or module will be placed in the lairage until the moment of slaughter. Often the crates or modules stay on the truck during lairage time, but they can also be unloaded.
• Depending on the duration of the journey the birds are required to receive water and/or food
• When the birds are due to being slaughtered, the crates or modules are brought into the slaughter house

Birds mostly are taken out of the crates or modules and shackled  by hand

Stress during transport

There are a lot of factors causing stress to end-of-lay hens at transport. Also prior to transport stress can be experienced by the management to prepare for transport.

Potential stressors prior to transport include:

• food deprivation: hens are deprived from food prior to transport to make sure their gut is empty.
• in some cases hens from separate compartments in a henhouse are gathered in one compartment to facilitate catching. This means that part of the flock has been moved and after moving the stocking density is double. Both the moving and the high density may cause stress.

Potential stressors during transport are:

• Catching of the birds, carrying them to the crates or modules and putting them in. Apart from the stress of the event itself (esp. fear related to chasing and inversion), there is a risk for trauma, which will cause pain and stress.
• Loading of the truck. Crates or modules are brought out of the henhouse and loaded onto the truck. The noise and new environment will cause stress.
• Actual transport: during the actual transport hens may be stressed by noise, trembling of the environment, rapid changes in climate, deprivation of food and water, high stocking densities, dehydration and injuries.
• Climatological changes: before the actual journey starts, the temperature in the crates/modules will raise and might easily exceed the comfort zone of the birds. This will also depend on the time of the year. As soon as the truck starts to drive the temperature will drop. Each time the truck stops, the temperature will raise. At the slaughter plant the crates or modules are placed in the lairage area, where the temperature will raise, even though shields and/or ventilation is installed. A study carried out in The Netherlands during winter time indicated that over a 4 hour period birds experienced a variation in temperature during transport of 20-25 degrees C.

For each potential stressor management and good equipment can reduce the actual stress experienced. Also the physical condition of the birds will have an influence.

Legal requirements

For transport of poultry a number of European Directions and Regulations need to be taken into account:

Transport regulation (EC, 1/2005):

Council Regulation (EC) No 1/2005 of 22 December 2004 on the protection of animals during transport and related operations and amending Directives 64/432/EEC and 93/119/EC and Regulation (EC) No 1255/97.

This regulation gives directions for all aspects regarding transport of animals and also provides definitions of transport and journey:

Journey: the entire transport operation from the place of departure to the place of destination, including any unloading, accommodation and loading occurring at intermediate points in the journey;

Transport: the movement of animals effected by one or more means of transport and the related operations, including loading, unloading, transfer and rest, until the unloading of the animals at the place of destination is completed;

Transport therefore is not only the journey, but also includes the catching, loading, lairage period up to the moment of unloading the truck.

Killing of animals (EC, 1099/2009):

Council Regulation (EC) No 1099/2009 of 24 September 2009 on the protection of animals at the time of killing.

Although this regulation does not specifically address transport, but mainly focusses on the killing of animals, it does contain some rules with regards to the period from arriving at the slaughter house until the moment of slaughter.

Specific hygiene rules for food of animal origin (EC, 853/2004):

Regulation (EC) No 853/2004 of the European Parliament and of the Council of 29 April 2004 laying down specific hygiene rules for food of animal origin.

This regulation contains several rules regarding animal welfare; also the HACCP procedure welfare at arrival at the slaughterhouse is influencing transport of poultry, because “the procedures must guarantee that each animal or, where appropriate, each lot of animals accepted onto the slaughterhouse premises:

(d) is clean;

(e) is healthy, as far as the food business operator can judge; and

(f) is in a satisfactory state as regards welfare on arrival at the slaughterhouse.

For transporting poultry European legislation requires the provision of water during long journeys. Apart from this there are European regulations regarding the length of the period without food.

In general the industry interprets the legislation as that it is not allowed to withhold water during transport of poultry for more than 12 hours and food for 24 hours. The latter is excluding the period of feed withdrawal on farm.

Preparing for transport

Before poultry is transported, food is withdrawn for some time so that the intestines are empty. This results in a minimum of defecation during transport and thus a minimum of soiling of the birds, in the crates as well as on the slaughter line. The latter is important for hygienic reasons. There is a wide variation in the duration of this food withdrawal time. For end-of-lay hens an average of 28 hours (including the time of the journey) was recorded in a field study in the Netherlands. Water should never be withdrawn until catching commences. For laying hens no legal requirements are in force regarding the duration of feed withdrawal, but there are several codes of Practice (see Feed withdrawal below). Water should never be withdrawn until catching commences.

At the slaughter plant

When birds arrive at the slaughter plant they may not be slaughtered immediately. The truck is then parked in the lairage area or the crates/modules are unloaded in the lairage. Ventilation and cover (for sun or rain) are used to maintain an acceptable climate for the birds.

Depending on the duration of the journey and the duration of their stay in the lairage area, birds need to be supplied with water and/or food.

Signs

Damage

Damage to birds may occur in various stages of the transport. Depopulation may cause broken and dislocated legs, especially if birds are carried on one leg. Not all housing systems are equally easy to depopulate. Although the overall incidence of leg fractures in DOA (dead-on-arrival) birds was low, Weeks et al (2012b) found in a small study of 24 loads that levels were 10 times greater for hens depopulated from colony (furnished) cages, than from free-range systems. Colony/furnished cases are now the only legal caged system within the EU. The depth of colony cages (from front opening to the rear) means it is hard to catch the hens at depopulation.

Pushing through narrow openings of crates often causes broken wings. More gentle and diligent work can reduce the number of breaks substantially. Systems with wider openings will also result in less broken bones.

In the crates birds may get bruises and scratches caused by other birds crawling over them. If crates are not closed properly, birds may get trapped, which may cause bruises, wounds or even death. Crates with damaged openings may lead to birds getting out too early, with the risk that they get stuck in the conveyer belt at the slaughter plant. Finally harsh handling during shackling may cause bruises, broken bones or wounds.

DOA’s

Due to all the stressors and possibly a suboptimal condition at the start of transport, not all birds reach the slaughter house alive. Global figures for dead on arrivals (DOAs) are unknown. Large surveys over several years in the Czech Republic and Italy revealed DOA percentages of resp. 1.01 and 1.22% (Voslarova et al., 2007; Petracci et al., 2006). Figures of 5 UK plants indicated a much lower percentage of DOAs: 0.27% (Weeks et al., 2012a). In 24 flocks monitored in The Netherlands during winter the DOA was on average 0.275% (Van Niekerk et al., 2014).

Mechanism

Mortality

Usually, mortality is indicated as DOAs (dead on arrival). This figure comprises both mortality during the journey and mortality in the lairage, as these are hard to distinguish. Mortality often is higher if transport distances are longer (Warriss et al., 1992a; Vecerek et al., 2006; Voslarova et al., 2007; Weeks et al., 2012a). Mortality will also be determined by the fitness of the flock and the temperature during transport.

Pain

As end-of-lay hens usually have very brittle bones, the catching and crating can easily cause fractures. Also dislocations, bruises and wounds are often recorded. All of these cause pain to the birds. Apart from that old hens often have unhealed old breakages, which are likely to be painful during handling.

A survey by Sandilands et al. (2005) found that 26-55% of laying hens had sustained fractures during production and 4-25% had obtained fractures during depopulation depending on the housing system. These figures indicate that a large proportion of the birds are at risk of experiencing pain during depopulation and transport.

Health status

European legislation dictates that birds that are not fit for travel, should only be transported if this would not cause an increase in suffering. As this cannot be realised for sick and injured birds, they should therefore be selected prior to transport. The catching crew should be instructed how to deal with unfit birds.

Deprivation

Prior to transport birds are usually deprived of food. Water is always provided.

In general it is advised to start fasting laying hens in the morning of the day of depopulation. In practice there is a lot of variation in the timing of empty feeders, and thus the actual duration of food deprivation. In a Dutch study birds were deprived for an average of 18 hours before transport started (Van Niekerk et al., 2014). Including transport this was on average 28 hours, with extremes up to 43.5 hours. No clear legal limits are set, although several Codes of Practice do give directions as to what limits should be respected (see feedwithdrawal below).

Climatic stress

Heat stress is thought to be the major contributor to both deaths (attributed to 40% of DOAs by Bayliss and Hinton, 1990) and overall transit stress in broilers. For laying hens the risks for heat stress is lower due to a usually bad feather cover. The degree of thermal stress experienced by birds in transit depends on the duration and intensity of both heat and cold stressors. In the UK risk for DOAs was increased by longer travelling distances and lower external air temperature (Weeks et al., 2012). Vecerek et al., (2006) indicted that hot summer weather or cold winter weather were associated with higher losses. Chauvin et al. (2011) pointed to rain and wind causing an increased risk of broiler DOA. Side curtains are used to reduce weather and climatological influences, but even in winter, these often restrict ventilation too much and excessive heat and moisture levels build up around the birds (Mitchell et al., 1992; Webster et al., 1992; Kettlewell et al., 1993; Burlinguette et al., 2012), leading to critical and lethal thermal conditions (Filho et al, 2008).

The birds experience climatological extremes during cold winter or hot summer climate, but also during the stationary parts of the transportation process (i.e. loading, unloading and waiting at the factory (Ritz et al., 2005).

Several studies indicated that there is a large variation in climate depending on the position on the truck (Webster et al., 1992; Kettlewell et al., 1993; Weeks et al., 1997; Richards et al., 2012). Especially naturally ventilated trucks mostly show this large variation. Studies of the aerodynamics of full-size and scale models of one design of vehicle, including a trailer, have shown that, when moving, air predominantly enters at the lower rear of the vehicle and moves forward to exit at the front (Baker et al., 1996, Hoxey et al., 1996). In certain positions there is virtually no air movement to dissipate the body heat produced by the birds. Weeks et al (1997) calculated that average air speeds immediately surrounding the birds in moving vehicles varied between 0.9 and 2.4 m per s with maxima of 6.0 ms-1. Based on data from loggers in eight positions within loads of end of lay hens transported in modules, Richards et al., (2012) confirmed that both when travelling and in lairage some parts of the load tracked outside air temperatures whereas others were dominated by bird heat. Conditions also varied within modules, with upper and central drawers unsurprisingly being warmer. Thermal ‘hot’ or ‘cold’ spots within loads may lead to deaths due to climatic conditions and excessive or inadequate ventilation (Hunter et al., 1997).

There are also large differences between conditions on moving and on stationary vehicles, again primarily due to ventilation and speed of air movement. Controlled and uniform ventilation in trucks therefore is essential. Vehicles fitted with both side curtains and roof-mounted inlet fans were generally able to maintain climate in the comfortable range (Weeks et al., 1997). These authors suggested air speeds within bird crates or modules should be maintained between 0.3 and 1.0 ms^-1 except in extremely hot weather. Ventilation requirement is between 100 and 600 cubic metres per hour for typical commercial loads. Kettlewell et al. (2000) proposed that 2.2 m³.h^-1 per kg of chickens was sufficient for uniformly ventilated loads in temperate conditions (up to 20 ^oC).

Fear

Transportation is an extremely stressful process for commercial poultry. From a relatively calm and stable environment the birds are suddenly taken to an unknown situation, with various stressful stimuli such as noise, vibrations, deprivation of food and water, extreme climatological circumstances and high stocking densities. The greater the duration of exposure to stressors, the greater the integrated stress for the bird. The resistance of birds to handling (Zulkifli et al., 2000) and transportation stressors (Kolb and Seehawer, 2001) may be enhanced by adding ascorbic acid (vitamin C) to the drinking water.

Fear or stress reactions can be modified by changes in handling procedures. Jones (1992) found that the TI (tonic immobility) response (indicating fear) of both broilers and hens was reduced by gentle handling.

Risk factors

Farm factors

Housing system

Laying hens are kept in a variety of housing systems, varying from small sized enriched cages to large non-cage units. Although the majority of hens in Europe are kept in cages, especially in Northern Europe the number of non-cages systems is increasing. Non-cage systems comprise simple single tier barn units, but also multitier aviary systems.

With regards to risk for injuries and DOAs (birds dead on arrival) the housing system does have an influence:

• First the housing system can have an influence on the health of the birds and thus on the fitness for travel. In non-cage systems birds are more likely to come into contact with their own manure, which means a risk for worms, coccidiosis and infectious diseases. These diseases form a risk for bird health and often cause mortality. Weeks et al (2012a) found higher mortality in non-cage systems compared to colony cages. They also found an increased risk of DOA in flocks with poor feather cover, poor health, lower body weight and higher cumulative mortality.
• Second the housing system as such can have an influence on the ease of catching the birds. Furnished cages have cage doors and the depth of the cage makes it difficult to catch the birds. Having people catching birds on both sides of the system or people driving the birds to the catchers may help. Another difficulty of these systems is the number of tiers and accessibility of the cages. Finally cage houses often are large, increasing the distance from cage to truck. If catchers have to walk the full length of the house many times, this will influence their handling of birds and may result in extra injuries. Non-cage systems require catching birds in the dark. At night, the majority of birds are on the top floor, which requires catchers to climb onto the system, catch birds and hand them over to helpers down in the litter area. As in cages bids have to be drawn from behind perches, feed troughs and out of nest boxes, but under dark circumstances this may lead to more damage to the birds. Also catchers often have to walk through the litter, which is a very uneven surface and may cause birds to bounce into furniture, possibly leading to injured birds. Large henhouses often are subdivided into sections by means of wire. Walking from one section to the other is possible, but doors have to be opened and as catchers are passing these doors in the dark, there is an additional risk for birds bouncing into door posts.

Aisles and doorways

The efficiency of catching and crating birds is also influenced by the condition of the aisles in housing systems. Wide aisles with clean concrete floors allow the use of carts or small motorized equipment to bring crates into the house, thus reducing the distance birds need to be carried.

Other factors may also influence the possibilities to bring crates into the house, such as the size of doorways and obstacles preventing the use of carts.

On-farm management

Health status of the birds

Healthy birds will be more capable to endure the stress of transport and arrive at the slaughter house in good condition. Birds with some kind of health condition, but still fit enough for travel, are more likely to die during transport. To increase the chance for survival additional measures can be taken. For instance, vitamin c provision through the drinking water prior to transport can reduce the effects of stress and may increase survival rate.

Litter removal

Removing litter from the aisles will enable the use of carts in the house or smoothen the path catchers need to walk. This will lead to less damaged birds.

Feed withdrawal

In general it is advised to withdraw food several hours before catching the birds so that the intestines are empty and no soiling of the birds with manure occur, in the crates as well as on the slaughter line. Common practice is to have the feeders empty in the morning of the day the birds will be transported. However, there is a lot of variation. There is discussion about the legally allowed duration of this feed deprivation. For laying hens no legal requirements are in force, but there are several codes of Practice (see Feed withdrawal below).

Birds collected in 1 section of the house

To reduce walking distances for the catchers sometimes birds from the far compartments are moved to the front compartments on the afternoon prior to depopulation. Although this moving of birds was done in a calm way, Van Niekerk et al. (2014) found more damaged birds at the slaughter house for this practice compared to flocks that had not been moved.

Catching methods

Hens are removed from cages either individually or in groups of 2 or 3 by pulling them out by one leg despite recommendations to handle poultry by two legs (e.g. UK Codes of Recommendation). In non-cage systems birds are taken from the perches at night. In aviary systems usually groups of 3 birds are held by one leg and brought outside to the crates. If the hen house is suitable, the crates may be brought in on carts, reducing the distance catchers have to walk with the birds. Experienced catching crews work calmly and with groups in each aisle, working in line from one end to the other end of the house. This causes a minimum of disturbance of the birds, reducing the number of birds that start running around. Birds that are moving away are collected at a later stage, when they have sat down elsewhere.

A direct comparison of different catching and carrying methods for end-of-lay hens showed that plasma corticosterone (stress hormone) concentrations were significantly higher when they were removed from their cages three at a time and carried in an inverted position from the house, than when they were removed singly and crated before removal from the house (Knowles and Broom, 1993).

Transport

System

Kristensen et al. (2001) evaluated a modular system for depopulating battery cages and found a significant reduction in the time each bird was handled from 64.5 s to 4.5 s. Compared with manual handling there was no difference in the proportion of damaged birds in the small trial, but the catchers preferred the modular system.

Van Niekerk et al. (2014) found that the use of carts to bring crates into the henhouse reduced the percentage of damaged birds in the slaughter plant.

Type of doors

Crates or modules with large doors will reduce the risk of broken wing. Sliding doors may reduce the incidence of trapped birds.

Number of birds/crate

The number of birds per crate influences the microclimate around the birds. Higher stocking densities may be used in winter, but precautions should be taken for those birds during the time in lairage as temperatures may get too high. Based on recent research (Richards et al., 2012) there is a strong argument for using different stocking rates in different areas of the load (in particular for reduced numbers in drawers at the top-front of the load) if this could be achieved in practice.

Delezie et al (2007) found that stocking density during transit had a greater influence on levels of stress in broilers than feed withdrawal or transportation. The stocking densities recommended by European legislation (EC, 2005) may be used as a guide that needs adjusting according to weather, bird condition and journey duration.

Guideline of space allowances for poultry in transit (EU, 2005)

Climate control on the truck

All studies addressing climate during transport found a large variation depending on the position on the truck (Webster et al., 1992; Kettlewell et al., 1993; Weeks et al., 1997; Richards et al., 2012), with naturally ventilated trucks showing the largest variation. Therefore temperature control on trucks is essential to maintain temperatures at an acceptable level. To realise this for all birds, temperature recording should be done on all trucks on various locations on the truck in close vicinity to the birds. Temperatures should be both recorded and linked to an in-cab monitoring and alarm system. As a guide, that should be modified according to individual loads and vehicle designs, Weeks et al (1997) indicated poorly-feathered end-of-lay birds at 22-28^oC were likely to be thermally comfortable at the usual high stocking densities. EFSA (2011) recommended that specific thermal limits should be defined. In winter it is especially important to minimise wind chill by the use of curtains and parking in the lea of buildings or trees and to avoid birds becoming wet.

By means of trailer roof vents and side curtains on-board temperature can be varied and maintained within acceptable limits (Burlinguette et al., 2012). during milder ambient conditions (9.8°C) on-board temperature ranged between 10.3 and 16.7°C if both vents and curtains were open. As external temperatures dropped, the side curtains and some of the roof vents were closed. This resulted in increasingly variable and more extreme thermal conditions, with heat and moisture accumulated along the mid-line of the load near the front of the lead trailer and near the back of the rear trailer. At an ambient temperature of -22.1°C, temperatures within the trailer varied widely between -20.7 to 21.7°C with an estimated 58.6% of the load volume being exposed to temperatures below 0°C. In addition, the trailer humidity ratio rose and conditions approached saturation (relative humidity>80%) in 55.2% of the load volume. Rectal temperatures showed that during winter weather in Canada, when the trailer is closed up and tarped, both hypothermia and hyperthermia occurred within the same trailer (Knezacek et al., 2010).

Vibrations

Chickens find vibration below 5 Hz particularly aversive, Randall et al. (1997) concluded that the resonant frequencies of 1-5 Hz found on transporters are undesirable. Thus vibration should be reduced, for example by using air suspension. Appropriate methodology to compare aversiveness of concurrent stressors during transport is being developed, initially using thermal and vibrational stressors (e.g. MacCalium et al., 2003).

Duration of the journey

Typical times in transit are unreported in most countries, but vary considerably. A small study of 24 commercial end-of-lay hen journeys in the UK found mean marketing time to range from 5.4 – 17.6 h (Richards et al., 2012). In the USA and Canada a review of DOAs (birds dead on arrival) by Newberry et al., (1999) found a substantial increase in hen mortality with marketing time for example from 0.7% (under 12 h) to 9.9% (over 24 h). A study in The Netherlands on 24 commercial layer flocks revealed a journey time of on average 2 hours and a total transport duration (thus including time in lairage) of on average 10 hours (Van Niekerk et al., 2014). These flocks were all slaughtered in the same plant in the Northern part of The Netherlands. Flocks located in the southern part are mostly slaughtered in Belgium and journey times will be limited. Some of the Dutch flocks are slaughtered in Eastern Europe (e.g. Poland), resulting in long journeys and even longer transport durations.

Facilities (access to water/feed)

In general no food or water is supplied to end-of-lay hens during the journey. However, for long journeys water supply is obligatory on the trucks and for even longer distances also food should be supplied.

For transport of pullets and breeding stock water supply systems have been developed for application on trucks. Mostly these comprise a water tank connected with tubes to fixed water systems in container units. For providing water to birds in crates different systems are used. These consist of loose tube systems that are attached to the crates. Side branches with nipple drinkers are stuck into the crates. The system is placed after the crates are loaded on the truck and is connected to a water tank on the truck.

A Dutch slaughter plant has water supply for end-of-lay hens in the lairage. This is realized by sliding tubes with nipple drinkers between the crates.

Solid food is never supplied to birds on transit. Apart from the issue of soiling with manure, experts indicate that birds on transport easily vomit and can choke in the food. Instead liquid nutrients are added to the drinking water.

Climate during transport

EFSA (2011) advices specific temperature limits during transport. They regard 24 – 25°C in the containers as a maximum for broilers, at a relative humidity of 70%. EFSA also advices to use mechanical ventilation for transports over 4 hours. Weeks et al. (1997) indicate that air velocity during transport should be 0.3 – 1.0 m/s at environmental temperatures of 10 – 15°C for broilers and 22–28°C for poorly feathered laying hens. Stocking density in the crates plays an important role and should be adjusted according to body weight of the birds and climatological circumstances (Mitchell and Kettlewell, 1998).

At the slaughterplant

Post transport handling and environment

Thermal conditions at the end of the journey must be considered as it can take 2-3 hours to manually unload pullets. Spent hens may also have to wait at the processing plant either on the vehicle or unloaded in modules or stacks of crates. In both instances a well-designed lairage is preferable to remaining outside exposed to the elements. It is important that the birds themselves receive adequate ventilation. The model birds used by Webster et al (1992) and Weeks et al. (1997) indicated that the hens frequently experienced conditions of substantial heat and cold stress in lairage during loading and unloading. Van Niekerk et al. (2014) measured temperatures during transport and lairage. Despite the use of a covered lairage and ventilation, temperatures clearly went up substantially during lairage. Thus the duration of such times needs to be kept to a minimum of preferably less than 1 hour.

A controlled environment providing adequate ventilation while avoiding excessive wind and air movement (except in hot weather) onto the birds is highly desirable. There should also be sufficient space around each module or stack for effective air exchange and flow. Monitoring the condition of birds and their environment in lairage is as necessary as it is during the journey. In practical terms, birds observed to be panting will become progressively dehydrated and increasingly heat stressed.

Following arrival at the processing plant most end-of-lay hens are manually removed from the containers. Where electrical stunning is used, live birds are suspended by their legs from shackles for conveyance to the bath. Many birds react to this potentially painful procedure by struggling, flapping their wings and attempting to righten themselves. This can lead to injury and reduces the chance that the bird will be effectively stunned prior to slaughter. To reduce the stress of hanging birds in shackles, Liner et al. (2011) found that struggling was reduced through the use of a breast support conveyor. Observations in U.S. slaughter plants showed that providing a breast rub made from strips of smooth conveyor belting will also reduce struggling and flapping.

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Shackling and stunning

Bird welfare is greatly improved when the labour intensive, stressful and often painful procedure of removing them from the containers and hanging them on shackles is eliminated. Controlled atmosphere (gas) stunning of chickens is now the commercial norm in some countries, with welfare and meat quality benefits such as reduced breast muscle haemorrhaging and bone breakages (Raj et al., 1997, Hoen and Lankhaar, 1999). Automation of shackling is has been investigated (e.g. Lee, 2001; Tinker et al., 2005) and is easier with gas-stunned birds than conscious ones that may flap, struggle and experience pain when shackled (Sparrey and Kettlewell, 1994).

Treatment

The benefits for animal welfare of training stockpeople and handlers is increasingly recognised (Hester, 2005) with specific benefits from altering attitudes (Hemsworth, 2003) and in handling and transport (Broom, 2005). Incentive programmes are also effective in reducing damage to birds. Providing incentive pay to employees may greatly reduce broken wings during catching of broilers. In U.S. plants, broken wings averaged 5 to 6%. The implementation of both incentive pay and auditing by restaurant company customers reduced broken wings to 1% or less in light weight birds and less than 3% in jumbo heavy birds.

Feed withdrawal

Regulations on feed withdrawal prior to transport and slaughter of end-of-lay hens

An inventory of available (mainly EU) regulations on feed withdrawal prior to transport and slaughter of laying hens indicated that no legal requirements appear to exist as to how long layers may be deprived of food prior to slaughter.

However, for broilers EC Directive 2007/43/EC prescribes that chickens kept for meat production should not be deprived of food for more than 12 hours before the expected time of slaughter.

Feed withdrawal in practice

In the Netherlands, Nepluvi, the Dutch Poultry Processing Industry Association, recommends a withdrawal period of a maximum of 24 hours (Welfare Code for Poultry Slaughter Plants, Art. 6 Vo 1099/2009). These are recommendations for good management practice to fulfil the requirements of Article 13 of EC Directive 1099_2009 on the protection of animals at the time of killing.

Codes of Practice in England, Wales, Scotland and Northern Ireland recommend that ‘feed, but not water, may be withheld for up to 12 hours prior to slaughter’ including ‘the catching, loading, transport, lairaging and unloading time’.

The Animal Welfare Approved label in the US requires that end-of-lay laying hens should not be deprived of food for more than 8 hours unless birds are crated overnight and go directly to slaughter in the morning, in which case feed withdrawal may exceed eight hours (Art. 13.4.5).

In the UK, the RSPCA Welfare Standards for Laying Hens (applied through the RSPCA Assured scheme), limit feed withdrawal periods to a maximum of 12 hours prior to slaughter.

Summary of EC regulations :

• COUNCIL REGULATION (EC) No 1/2005 of 22 December 2004 on the protection of animals during transport and related operations
• COUNCIL REGULATION (EC) No 1099/2009 of 24 September 2009 on the protection of animals at the time of killing
• COUNCIL DIRECTIVE 2007/43/EC of 28 June 2007 laying down minimum rules for the protection of chickens kept for meat production
• COUNCIL DIRECTIVE 98/58/EC of 20 July 1998 concerning the protection of animals kept for farming purposes

1. COUNCIL REGULATION (EC) No 1/2005 of 22 December 2004 on the protection of animals during transport and related operations specified under TECHNICAL RULES, CHAPTER III TRANSPORT PRACTICES that:

Where loading or unloading operations last for more than four hours, except for poultry: (a) appropriate facilities shall be available in order to keep, feed and water the animals outside the means of transport without being tied;

And under CHAPTER V WATERING AND FEEDING INTERVAL, JOURNEY TIMES AND RESTING PERIODS that

2.1. For poultry, domestic birds and domestic rabbits, suitable food and water shall be available in adequate quantities, save in the case of a journey lasting less than:

(a) 12 hours disregarding loading and unloading time; or

(b) 24 hours for chicks of all species, provided that it is completed within 72 hours after hatching.

2. COUNCIL REGULATION (EC) No 1099/2009 of 24 September 2009 on the protection of animals at the time of killing specifies in CHAPTER II GENERAL REQUIREMENTS in Article 3 General requirements for killing and related operations that business operators shall, in particular, take the necessary measures to ensure that animals:

(e) do not suffer from prolonged withdrawal of feed or water;

In addition, ANNEX II LAYOUT, CONSTRUCTION AND EQUIPMENT OF SLAUGHTERHOUSES (as referred to in Article 14, section 2.3) specifies that:

The water supply system in pens shall be designed, constructed and maintained so as to allow all animals at all times access to clean water without being injured or limited in their movements.

In addition, ANNEX III OPERATIONAL RULES FOR SLAUGHTERHOUSES (as referred to in Article 15) specifies that

1.2. … Animals which have not been slaughtered within 12 hours of their arrival shall be fed, and subsequently given moderate amounts of food at appropriate intervals. ….

1.5. For the purpose of slaughter, unweaned animals, lactating dairy animals, females having given birth during the journey or animals delivered in containers shall be given priority over other types of animal. If this is not possible, arrangements shall be made so as to relieve them from their suffering, in particular by:

(c) providing water in the case of animals delivered in containers

3. COUNCIL DIRECTIVE 2007/43/EC of 28 June 2007 laying down minimum rules for the protection of chickens kept for meat production specifies in ANNEX I REQUIREMENTS APPLICABLE TO HOLDINGS (under Feeding 2) that:

Feed shall be either continuously available or be meal fed and must not be withdrawn from chickens more than 12 hours before the expected slaughter time.

4. COUNCIL DIRECTIVE 98/58/EC of 20 July 1998 concerning the protection of animals kept for farming purposes specifies in the Annex under Feed, water and other substances that:
5. Animals must be fed a wholesome diet which is appropriate to their age and species and which is fed to them in sufficient quantity to maintain them in good health and satisfy their nutritional needs. No animal shall be provided with food or liquid in a manner, nor shall such food or liquid contain any substance, which may cause unnecessary suffering or injury.
6. All animals must have access to feed at intervals appropriate to their physiological needs.

16. All animals must have access to a suitable water supply or be able to satisfy their fluid intake needs by other means.

Importance

Economics

The numbers of poultry handled, transported and slaughtered is greater than any other livestock. The FAO estimate of poultry-meat production for 2012 is 106 million tonnes, 87% of which is from some 50 billion broilers. Laying hen numbers are about 6,400 million (Watt, 2011). It is common for production sites to place hundreds of thousands of chicks or pullets within 2-3 days, and to depopulate for slaughter equally swiftly. All birds are handled and transported at least twice.

After a productive year, hens are caught and transported to the slaughterhouse. End-of-lay hens are generally purchased ‘off farm’. Their economic value has increased slightly as markets, especially in Africa, develop. This has improved the care taken in handling and the investment in transport systems in some countries. Gradually the modular systems such as Anglia Autoflow and gas stunning are replacing loose crates handling and waterbath stunning. Many types of vehicle are used, but dedicated trucks with side curtains are increasingly common.

Further reading

Further reading by language

English

General

• Déborah Temple, Thea van Niekerk, Claire Weeks, Xavier Manteca, 2017. Guidelines end of lay. Hennovation (24 pp).

What is end of lay?

• Council Regulation (EC) No 1/2005 of 22 December 2004 on the protection of animals during transport and related operations and amending Directives 64/432/EEC and 93/119/EC and Regulation (EC) No 1255/97.
• Council Regulation (EC) No 1099/2009 of 24 September 2009 on the protection of animals at the time of killing.
• Regulation (EC) No 853/2004 of the European Parliament and of the Council of 29 April 2004 laying down specific hygiene rules for food of animal origin.

Signs

• Petracci, M., Bianchi, M., Cavani. C., Gaspari, P. and Lavazza, A. (2006) Preslaughter mortality in broiler chickens, turkeys and spent hens under commercial slaughtering. Poultry Science,85, 1660-1664.
• Voslarova, E., Janackova, B., Rubesova, L., Kozak, A., Bedanova, I., Steinhauser, L. and Vecerek, V. (2007) Mortality rates in poultry species and categories during transport for slaughter. Acta Veterinaria Brno, 76, S101-S108.
• Weeks, C.A., Brown, S.N., Richards, G.J., Wilkins, L.J. and Knowles, T.G. (2012a) Levels of mortality in hens by end of lay on farm and in transit to slaughter in Great Britain. Veterinary Record, 170, 25 647. (online)

Mechanism

Mortality

• Vecerek, V.; Grbalova, S.; Voslarova, E.; Janackova, B.; Malena, M. (2006) Effects of travel distance and the season of the year on death rates of broilers transported to poultry processing plants. Poultry Science, 85, 1881-1884.
• Voslarova, E., Janackova, B., Rubesova, L., Kozak, A., Bedanova, I., Steinhauser, L. and Vecerek, V. (2007) Mortality rates in poultry species and categories during transport for slaughter. Acta Veterinaria Brno, 76, S101-S108.
• Voslarova, E., Janackova, B., Vitula, F.., Kozak, A. and Vecerek, V. (2007) Effects of transport distance and the season of the year on death rates among hens and roosters in transport to poultry processing plants in the Czech Republic in the period from 1997 to 2004. Veterinarni medicina, 52, 262-266.
• Warriss, P.D., Bevis, E.A., Brown, S.N. and Edwards, J.E. (1992a) Longer journeys to processing plants are associated with higher mortality in broiler chickens. British Poultry Science 33, 201-206.
• Weeks, C.A., Brown, S.N., Richards, G.J., Wilkins, L.J. and Knowles, T.G. (2012a) Levels of mortality in hens by end of lay on farm and in transit to slaughter in Great Britain. Veterinary Record, 170, 25 647. (online)

Pain

• Sandilands, V., Sparks, N., Wilson, S. and Nevison, I. (2005) Laying hens at depopulation: the impact of the production system on bird welfare. British Poultry Abstracts, 1, 23-24.

Climatic stress

• Baker, C.J., Dalley, S., Yang, X., Kettlewell, P., and Hoxey, R. (1996) An investigation of the aerodynamic and ventilation characteristics of poultry transport vehicles. 2. Wind tunnel experiments. Journal of Agricultural Engineering Research 65, 97-113.
• Bayliss, P.A. and Hinton, M.H. (1990) Transportation of poultry with special reference to mortality rates. Applied Animal Behaviour Science 28, 93-118.
• Burlinguette, N.A., M.L. Strawford, J.M. Watts, H.L. Classen, P.J. Shand and T.G. Crowe. (2012) Broiler trailer thermal conditions during cold climate transport. Canadian Journal of Animal Science, 92, 109-122. doi:10.4141/cjas2011-027
• Chauvin C., Hillion, S., Balaine, L., Michel, V., Peraste, J., Petetin, I., Lupo, C., Le Bouquin, S. (2011) Factors associated with mortality of broilers during transport to slaughterhouse. Animal, 5 , 2, 287-293. DOI: 10.1017/S1751731110001916
• Filho, J.A.D.B., Vieira, F.M.C., Fonseca, B.H.F., Silva, I.J.O., Garcia, D.B., and Hildebrand, A. (2008) Poultry transport microclimate analysis through enthalpy comfort index (ECI): a seasonal assessment. Livestock Environment VIII, 639-643.
• Hoxey, R.P., Kettlewell, P.J., Meehan, A.M., Baker, C.J. and Yang, X. (1996) An investigation of the aerodynamic and ventilation characteristics of poultry transport vehicles. I. Full-scale measurements. Journal of Agricultural Engineering Research 65, 77-83.
• Hunter, R.R., Mitchell, M.A. and Matheu, C. (1997) Distribution of ‘dead on arrivals’ within the bio-load on commercial broiler transporters: correlation with climatic conditions and ventilation regimen. British Poultry Science 38, S7-S9.
• Kettlewell, P., Mitchell, M. and Meehan, A. (1993) The distribution of thermal loads within poultry transport vehicles. Agricultural Engineer 48, 26-30.
• Kettlewell, P.J., Hoxey, R.P. and Mitchell, M.A. (2000) Heat produced by broiler chickens in a commercial transport vehicle. Journal of Agricultural Engineering Research, 75, 315-326.
• Mitchell, M.A., Kettlewell, P.J. and Maxwell, M.H. (1992) Indicators of physiological stress in broiler chickens during road transportation. Animal Welfare 1, 92-103.
• Richards, G.J., Wilkins, L.J., Weeks, C.A., Knowles, T.G. and Brown, S.N. (2012) Evaluation of the microclimate in poultry transport module drawers during the marketing process of end of lay hens from farm to slaughter. Veterinary Record, in press
• Ritz, C.W. Webster, A.B. and Czarick, M. (2005) Evaluation of hot weather and incidence of mortality associated with broiler live haul. Journal of Applied Poultry Reseach, 14(3), 594-602.
• Vecerek, V.; Grbalova, S.; Voslarova, E.; Janackova, B.; Malena, M. (2006) Effects of travel distance and the season of the year on death rates of broilers transported to poultry processing plants. Poultry Science, 85, 1881-1884.
• Webster, A.J.F, Tuddenham, A., Saville, C.A. and Scott, G.A. (1992) Thermal Stress on Chickens in Transit. British Poultry Science, 34, 267-277.
• Weeks, C.A., Webster, A.J.F. and Wyld, H.M. (1997) Vehicle design and thermal comfort of poultry in transit. British Poultry Science, 38, 464-474.

Fear

• Jones, R.B. (1992) The nature of handling immediately prior to test affects tonic immobility fear reactions in laying hens and broilers. Applied Animal Behaviour Science 34, 247-254.
• Kolb, E. and Seehawer, J. (2001) Significance and application of ascorbic acid in poultry. Archiv fur Gerflugelkunde, 65, 106-113.
• Zulkifli, I., Norma, M.T.C., Chong, C.H and Loh, T.C. (2000) Heterophil to lymphocyte ratio and tonic immobility reactions to preslaughter handling in broiler chickens treated with ascorbic acid. Poultry Science, 79, 402-406.

Risk factors

On-farm management: Catching methods

• Knowles, T.G. and Broom, B.M. (1993) Effect of catching method on the concentration of plasma corticosterone in end-of-lay battery hens. Veterinary Record 133, 527-528.

Transport (general)

• Preparation of vehicle, driver and loading for poultry (Factsheet Animal Transport Guides)
• Preparing the catching of end-of-lay hens (Factsheet Animal Transport Guides)
• Preparing the catching of broilers (Factsheet Animal Transport Guides)

Transport: Number of birds/crate

• Delezie, E., Swennen, Q., Buyse, J. and Decuypere, E. (2007) The effect of feed withdrawal and crating density in transit on metabolism and meat quality of broilers at slaughter weight. Poultry Science, 86, 1414-1423.

Transport: Vibrations

• Burlinguette, N.A., M.L. Strawford, J.M. Watts, H.L. Classen, P.J. Shand and T.G. Crowe. (2012) Broiler trailer thermal conditions during cold climate transport. Canadian Journal of Animal Science, 92, 109-122. doi:10.4141/cjas2011-027
• EFSA (2011) Scientific opinion concerning the welfare of animals during transport. EFSA Journal, 9(1), 1966 [125 pp.]. doi:10.2903/j.efsa.2011.1966
• Kettlewell, P., Mitchell, M. and Meehan, A. (1993) The distribution of thermal loads within poultry transport vehicles. Agricultural Engineer 48, 26-30.
• Knezacek, T.D., Olkowski, A.A., Kettlewell, P.J., Mitchel, M.A., and Classen, H.L. (2010) Temperature gradients in trailers and changes in broiler rectal and core body temperature during winter transportation in Saskatchewan, Canadian Journal of Animal Sciences, DO110.4141/CJAsopo83.
• MacCaluim, J.M., Abeyesinghe, S.M., White, R.P. and Wathes, C.M. (2003) A continuous-choice assessment of the domestic fowl’s aversion to concurrent transport stressors. Animal Welfare, 12, 95-107.
• Randall, J.M., Duggan, J.A., Alami, M.A. and White, R.P. (1997) Frequency weightings for the aversion of broiler chickens to horizontal and vertical vibration. Journal of Agricultural Engineering Research, 68, 387-397.
• Richards, G.J., Wilkins, L.J., Weeks, C.A., Knowles, T.G. and Brown, S.N. (2012) Evaluation of the microclimate in poultry transport module drawers during the marketing process of end of lay hens from farm to slaughter. Veterinary Record, in press
• Webster, A.J.F, Tuddenham, A., Saville, C.A. and Scott, G.A. (1992) Thermal Stress on Chickens in Transit. British Poultry Science, 34, 267-277.
• Weeks, C.A., Webster, A.J.F. and Wyld, H.M. (1997) Vehicle design and thermal comfort of poultry in transit. British Poultry Science, 38, 464-474.

Transport: Facilities

• Newberry R.C., Webster A.B., Lewis N.J. and Van Arnam C. (1999) Management of spent hens. Journal of Applied Animal Welfare Science, 2, 13–29.
• Richards, G.J., Wilkins, L.J., Weeks, C.A., Knowles, T.G. and Brown, S.N. (2012) Evaluation of the microclimate in poultry transport module drawers during the marketing process of end of lay hens from farm to slaughter. Veterinary Record, in press

Transport: Climate during transport

• EFSA (2011) Scientific opinion concerning the welfare of animals during transport. EFSA Journal, 9(1), 1966 [125 pp.]. doi:10.2903/j.efsa.2011.1966
• Mitchell, M.A. and Kettlewell, P.J. (1998) Physiological stress and welfare of broiler chickens in transit: solutions, not problems! Poultry Science 77, 1803-1814.
• Weeks, C.A., Webster, A.J.F. and Wyld, H.M. (1997) Vehicle design and thermal comfort of poultry in transit. British Poultry Science, 38, 464-474.

At the slaughter plant: Post transport handling and environment

• Lines, J.A., Jones, T.A., Berry, P.S., Spence, J., and Schofield, C.R. (2011) Evaluation of breast support conveyor to improve poultry welfare on the shackle line, Veterinary Record, 168:129.
• Webster, A.J.F, Tuddenham, A., Saville, C.A. and Scott, G.A. (1992) Thermal Stress on Chickens in Transit. British Poultry Science, 34, 267-277.
• Weeks, C.A., Webster, A.J.F. and Wyld, H.M. (1997) Vehicle design and thermal comfort of poultry in transit. British Poultry Science, 38, 464-474.

At the slaughter plant: Shackling and stunning

• Hoen, T and Lankhaar, J. (1999) Controlled atmosphere stunning of poultry. Poultry Science 78 (2), 287-289.
• Lee, K.M. (2001) Design criteria for developing an automated live-bird transfer system. IEEE Transactions on Robotics and Automation, 17(4), 483-490.
• Raj, A.B.M., Wilkins, L.J., Richardson, R.I., Johnson, S.P. and Wotton, S.B. (1997) Carcase and meat quality in broilers either killed with a gas mixture or stunned with an electric current under commercial processing conditions. British Poultry Science 38, 169-174.
• Sparrey J.M., Kettlewell P.J. (1994) Shackling Of Poultry – Is It A Welfare Problem? Worlds’ Poultry Science Journal 50, 167-176.
• Tinker, D., Berry, P., White, R., Prescott, N., Welch, S. and Lankhaar., J. (2005) Improvement in the welfare of broilers by changes to a mechanical unloading system. Journal of Applied Poultry Research, 14 (2), 330-337.

Treatment

• Broom, D.M. (2005) The effects of land transport on animal welfare. Revue Scientifique Et Technique-Office International Des Epizooties 24 (2), 683-691.
• Hemsworth, P.H. (2003) Human-animal interactions in livestock production. Applied Animal Behaviour Science, 81(3), 185-198.

Importance

• Watt Executive Guide to World Poultry Trends (2011) www.wattagnet.net (accessed Aug 2012)

Czech

Mechanism

Mortality

• Voslarova, E., Janackova, B., Vecerek, V. and Malena, M. (2007) Počty uhynulých slepic a kohoutů při přepravě na porážku v letech 1997 až 2006 (Numbers of hens and roosters that died during transport to slaughter from 1997 to 2006). In Ochrana zvířat a welfare Conference Proceedings. Brno: VFU Brno, pp. 186-188.
• Voslarova, E. and Vecerek, V. (2015) Vývoj úhynů nosnic při přepravě na jatky v ČR v období let 1997 – 2014. (Mortality of laying hens in association with their transport for slaughter in the period from 1997 to 2014). In Ochrana zvířat a welfare Conference Proceedings. Brno: VFU Brno, pp. 188-191.
• Voslarova, E. and Vecerek, V. (2015) Vliv vzdálenosti a ročního období na úhyn brojlerů a nosnic při přepravě na porážku. (Impact of transport distance and season on mortality of broiler chickens and laying hens transported for slaughter). In Drůbež 2015 Conference Proceedings, Brno: VFU Brno, pp. 11. (abstract)

Nederlands

• Van Niekerk, T. G. C. M., H. Gunnink, and B. F. J. Reuvekamp. (2014). Welzijn van uitgelegde hennen tijdens vangen en vervoer in de winterperiode. Wageningen UR Livestock Research; Report 758.

Further reading (by language in alphabetical order)

English

• Baker, C.J., Dalley, S., Yang, X., Kettlewell, P., and Hoxey, R. (1996) An investigation of the aerodynamic and ventilation characteristics of poultry transport vehicles. 2. Wind tunnel experiments. Journal of Agricultural Engineering Research 65, 97-113.
• Bayliss, P.A. and Hinton, M.H. (1990) Transportation of poultry with special reference to mortality rates. Applied Animal Behaviour Science 28, 93-118.
• Broom, D.M. (2005) The effects of land transport on animal welfare. Revue Scientifique Et Technique-Office International Des Epizooties 24 (2), 683-691.
• Burlinguette, N.A., M.L. Strawford, J.M. Watts, H.L. Classen, P.J. Shand and T.G. Crowe. (2012) Broiler trailer thermal conditions during cold climate transport. Canadian Journal of Animal Science, 92, 109-122. doi:10.4141/cjas2011-027
• Chauvin C., Hillion, S., Balaine, L., Michel, V., Peraste, J., Petetin, I., Lupo, C., Le Bouquin, S. (2011) Factors associated with mortality of broilers during transport to slaughterhouse. Animal, 5 , 2, 287-293. DOI: 10.1017/S1751731110001916
• Council Regulation (EC) No 1/2005 of 22 December 2004 on the protection of animals during transport and related operations and amending Directives 64/432/EEC and 93/119/EC and Regulation (EC) No 1255/97.
• Council Regulation (EC) No 1099/2009 of 24 September 2009 on the protection of animals at the time of killing.
• EFSA (2011) Scientific opinion concerning the welfare of animals during transport. EFSA Journal, 9(1), 1966 [125 pp.]. doi:10.2903/j.efsa.2011.1966
• Delezie, E., Swennen, Q., Buyse, J. and Decuypere, E. (2007) The effect of feed withdrawal and crating density in transit on metabolism and meat quality of broilers at slaughter weight. Poultry Science, 86, 1414-1423.
• Filho, J.A.D.B., Vieira, F.M.C., Fonseca, B.H.F., Silva, I.J.O., Garcia, D.B., and Hildebrand, A. (2008) Poultry transport microclimate analysis through enthalpy comfort index (ECI): a seasonal assessment. Livestock Environment VIII, 639-643.
• Hemsworth, P.H. (2003) Human-animal interactions in livestock production. Applied Animal Behaviour Science, 81(3), 185-198.
• Hoen, T and Lankhaar, J. (1999) Controlled atmosphere stunning of poultry. Poultry Science 78 (2), 287-289.
• Hoxey, R.P., Kettlewell, P.J., Meehan, A.M., Baker, C.J. and Yang, X. (1996) An investigation of the aerodynamic and ventilation characteristics of poultry transport vehicles. I. Full-scale measurements. Journal of Agricultural Engineering Research 65, 77-83.
• Hunter, R.R., Mitchell, M.A. and Matheu, C. (1997) Distribution of ‘dead on arrivals’ within the bio-load on commercial broiler transporters: correlation with climatic conditions and ventilation regimen. British Poultry Science 38, S7-S9.
• Jones, R.B. (1992) The nature of handling immediately prior to test affects tonic immobility fear reactions in laying hens and broilers. Applied Animal Behaviour Science 34, 247-254.
• Kettlewell, P., Mitchell, M. and Meehan, A. (1993) The distribution of thermal loads within poultry transport vehicles. Agricultural Engineer 48, 26-30.
• Kettlewell, P.J., Hoxey, R.P. and Mitchell, M.A. (2000) Heat produced by broiler chickens in a commercial transport vehicle. Journal of Agricultural Engineering Research, 75, 315-326.
• Knezacek, T.D., Olkowski, A.A., Kettlewell, P.J., Mitchel, M.A., and Classen, H.L. (2010) Temperature gradients in trailers and changes in broiler rectal and core body temperature during winter transportation in Saskatchewa, Canadian Journal of Animal Sciences, DO110.4141/CJAsopo83.
• Knowles, T.G. and Broom, B.M. (1993) Effect of catching method on the concentration of plasma corticosterone in end-of-lay battery hens. Veterinary Record 133, 527-528.
• Kolb, E. and Seehawer, J. (2001) Significance and application of ascorbic acid in poultry. Archiv fur Gerflugelkunde, 65, 106-113.
• Lee, K.M. (2001) Design criteria for developing an automated live-bird transfer system. IEEE Transactions on Robotics and Automation, 17(4), 483-490.
• Lines, J.A., Jones, T.A., Berry, P.S., Spence, J., and Schofield, C.R. (2011) Evaluation of breast support conveyor to improve poultry welfare on the shackle line, Veterinary Record, 168:129.
• MacCaluim, J.M., Abeyesinghe, S.M., White, R.P. and Wathes, C.M. (2003) A continuous-choice assessment of the domestic fowl’s aversion to concurrent transport stressors. Animal Welfare, 12, 95-107.
• Mitchell, M.A. and Kettlewell, P.J. (1998) Physiological stress and welfare of broiler chickens in transit: solutions, not problems! Poultry Science 77, 1803-1814.
• Mitchell, M.A., Kettlewell, P.J. and Maxwell, M.H. (1992) Indicators of physiological stress in broiler chickens during road transportation. Animal Welfare 1, 92-103.
• Newberry R.C., Webster A.B., Lewis N.J. and Van Arnam C. (1999) Management of spent hens. Journal of Applied Animal Welfare Science, 2, 13–29.
• Petracci, M., Bianchi, M., Cavani. C., Gaspari, P. and Lavazza, A. (2006) Preslaughter mortality in broiler chickens, turkeys and spent hens under commercial slaughtering. Poultry Science,85, 1660-1664.
• Raj, A.B.M., Wilkins, L.J., Richardson, R.I., Johnson, S.P. and Wotton, S.B. (1997) Carcase and meat quality in broilers either killed with a gas mixture or stunned with an electric current under commercial processing conditions. British Poultry Science 38, 169-174.
• Randall, J.M., Duggan, J.A., Alami, M.A. and White, R.P. (1997) Frequency weightings for the aversion of broiler chickens to horizontal and vertical vibration. Journal of Agricultural Engineering Research, 68, 387-397.
• Regulation (EC) No 853/2004 of the European Parliament and of the Council of 29 April 2004 laying down specific hygiene rules for food of animal origin.
• Richards, G.J., Wilkins, L.J., Weeks, C.A., Knowles, T.G. and Brown, S.N. (2012) Evaluation of the microclimate in poultry transport module drawers during the marketing process of end of lay hens from farm to slaughter. Veterinary Record, in press
• Ritz, C.W. Webster, A.B. and Czarick, M. (2005) Evaluation of hot weather and incidence of mortality associated with broiler live haul. Journal of Applied Poultry Reseach, 14(3), 594-602.
• Sandilands, V., Sparks, N., Wilson, S. and Nevison, I. (2005) Laying hens at depopulation: the impact of the production system on bird welfare. British Poultry Abstracts, 1, 23-24.
• Sparrey J.M., Kettlewell P.J. (1994) Shackling Of Poultry – Is It A Welfare Problem? Worlds’ Poultry Science Journal 50, 167-176.
• Tinker, D., Berry, P., White, R., Prescott, N., Welch, S. and Lankhaar., J. (2005) Improvement in the welfare of broilers by changes to a mechanical unloading system. Journal of Applied Poultry Research, 14 (2), 330-337.
• Vecerek, V.; Grbalova, S.; Voslarova, E.; Janackova, B.; Malena, M. (2006) Effects of travel distance and the season of the year on death rates of broilers transported to poultry processing plants. Poultry Science, 85, 1881-1884.
• Voslarova, E., Janackova, B., Rubesova, L., Kozak, A., Bedanova, I., Steinhauser, L. and Vecerek, V. (2007) Mortality rates in poultry species and categories during transport for slaughter. Acta Veterinaria Brno, 76, S101-S108.
• Voslarova, E., Janackova, B., Vitula, F.., Kozak, A. and Vecerek, V. (2007) Effects of transport distance and the season of the year on death rates among hens and roosters in transport to poultry processing plants in the Czech Republic in the period from 1997 to 2004. Veterinarni medicina, 52, 262-266.
• Warriss, P.D., Bevis, E.A., Brown, S.N. and Edwards, J.E. (1992a) Longer journeys to processing plants are associated with higher mortality in broiler chickens. British Poultry Science 33, 201-206.
• Watt Executive Guide to World Poultry Trends (2011) www.wattagnet.net (accessed Aug 2012)
• Webster, A.J.F, Tuddenham, A., Saville, C.A. and Scott, G.A. (1992) Thermal Stress on Chickens in Transit. British Poultry Science, 34, 267-277.
• Weeks, C.A., Brown, S.N., Richards, G.J., Wilkins, L.J. and Knowles, T.G. (2012a) Levels of mortality in hens by end of lay on farm and in transit to slaughter in Great Britain. Veterinary Record, 170, 25 647. (online)
• Weeks, C.A., Webster, A.J.F. and Wyld, H.M. (1997) Vehicle design and thermal comfort of poultry in transit. British Poultry Science, 38, 464-474.
• Zulkifli, I., Norma, M.T.C., Chong, C.H and Loh, T.C. (2000) Heterophil to lymphocyte ratio and tonic immobility reactions to preslaughter handling in broiler chickens treated with ascorbic acid. Poultry Science, 79, 402-406.

Czech

• Voslarova, E., Janackova, B., Vecerek, V. and Malena, M. (2007) Počty uhynulých slepic a kohoutů při přepravě na porážku v letech 1997 až 2006 (Numbers of hens and roosters that died during transport to slaughter from 1997 to 2006). In Ochrana zvířat a welfare Conference Proceedings. Brno: VFU Brno, pp. 186-188.
• Voslarova, E. and Vecerek, V. (2015) Vývoj úhynů nosnic při přepravě na jatky v ČR v období let 1997 – 2014. (Mortality of laying hens in association with their transport for slaughter in the period from 1997 to 2014). In Ochrana zvířat a welfare Conference Proceedings. Brno: VFU Brno, pp. 188-191.
• Voslarova, E. and Vecerek, V. (2015) Vliv vzdálenosti a ročního období na úhyn brojlerů a nosnic při přepravě na porážku. (Impact of transport distance and season on mortality of broiler chickens and laying hens transported for slaughter). In Drůbež 2015 Conference Proceedings, Brno: VFU Brno, pp. 11. (abstract)

Nederlands

• Van Niekerk, T. G. C. M., H. Gunnink, and B. F. J. Reuvekamp. (2014). Welzijn van uitgelegde hennen tijdens vangen en vervoer in de winterperiode. Wageningen UR Livestock Research; Report 758.