Advances in Poultry Welfare

By Elsevier Science

Advances in Poultry Welfare provides a targeted overview of contemporary developments in poultry welfare. The reviews in the volume address topical issues related to poultry welfare research and assessment, with a focus on identifying practical strategies for improvement as well as information gaps that remain to be filled.

Part One provides an introduction to poultry production systems and gives a broad overview of current poultry welfare issues. Part Two moves on to review several aspects of poultry management, focusing on hatchery practices, early rearing, and slaughter. Part Three deals with welfare assessment on the farm, while Part Four explores continuing challenges, such as feather pecking and skeletal problems. This is followed in Part Five by a discussion of emerging issues, with chapters covering alternative parasite control methods, backyard poultry production, mass depopulation, and genetic approaches to reducing the impact of environmental stressors on welfare.

This book is an essential part of the wider ranging series Advances in Farm Animal Welfare, with coverage of cattle, sheep, pigs, and poultry.

With its expert editor and international team of contributors, Advances in Poultry Welfare is a key reference tool for welfare research scientists and students, veterinarians involved in welfare assessment, and indeed anyone with a professional interest in the welfare of poultry.

• Provides in-depth reviews of emerging topics, research and applications in poultry welfare
• Integral part of a wider series, Advances in Agricultural Animal Welfare, which will provide comprehensive coverage of animal welfare of the world’s major farmed animals
• Covers a range of topical issues within the field, from beak-trimming and skeletal problems, to early rearing and the design and management of poultry production systems
• Edited by a distinguished leader in the field

• Language: English
• Publisher: Elsevier Science
• Release date: Nov 30, 2017
• ISBN: 9780081009307

Book preview

needed.

Part I

Introduction

Outline

1 Overview of commercial poultry production systems and their main welfare challenges

1

Overview of commercial poultry production systems and their main welfare challenges

Darrin M. Karcher¹ and Joy A. Mench²,    ¹Purdue University, West Lafayette, IN, United States,    ²University of California, Davis, CA, United States

Abstract

Commercial poultry production has changed since the 1950s. Genetic selection has resulted in two different types of commercial poultry, meat and egg-laying birds. Production systems for meat birds (chickens, turkeys, and ducks) are similar in their configuration and management, although there are some differences due to the species being grown and the desired days to market. In contrast, the table-egg industry is changing rapidly due to animal welfare concerns, particularly in developing countries, and egg-laying hens are now produced in a multitude of systems requiring different types of management expertise. We provide an overview of the commercial production systems commonly used for rearing meat birds and egg-laying hens. We also identify some of the major welfare challenges related to health and behavior within current systems, and discuss emerging consumer preferences that will shape poultry production systems, and their associated welfare concerns, in the near future.

Keywords

Turkeys; ducks; broilers; laying hens; pullets; housing system; welfare; health; behavior

1.1 Introduction

Commercial poultry production practices have changed dramatically since the 1950s. Most commercial poultry are now raised entirely indoors, in environmentally or semi-environmentally controlled buildings. They are managed to maximize production, for example by feeding diets that are formulated for their nutritional needs at various stages of the rearing or egg-laying cycle and by providing controlled photoperiods and light intensities to stimulate growth or egg laying. A major source of change has been the intense genetic selection for either growth or egg laying, leading to the development of two different types of poultry—meat birds and table-egg layers—which are managed by two separate sectors of the poultry industry.

As a result of these factors as well as advances such as better prevention and control of disease via vaccines and antibiotics, the poultry industry has grown significantly over the last few decades, with the consumption of both poultry meat and eggs increasing globally, an increase that is predicted to continue, particularly in developing countries (NRC, 2015). Although many different species of poultry are grown around the world for meat and eggs, the three primary species produced commercially are chickens (for meat and table eggs), ducks (mainly Pekin ducks for meat), and turkeys (for meat).

As production has grown and intensified, so too have concerns about animal welfare. As early as 1965, the influential U.K. Brambell Committee "Report of the Technical Committee to Enquire into the Welfare of Animals Kept under Intensive Livestock Husbandry Systems" identified a number of potential welfare issues in commercial poultry production, including beak trimming (which they suggested might cause pain), the restriction of space and behavior in conventional cages for hens, risks of disease and cannibalism in loose housing systems for hens, the use of dim lighting for both meat chickens and laying hens, high stocking densities for broiler chickens and turkeys, and the potential for mechanical failure in automated housing systems (Brambell, 1965). Most of these concerns persist, and others have emerged as commercial production systems have evolved and public interest in animal welfare has continued to intensify, particularly in developed countries.

In this chapter we describe the main systems used for rearing commercial meat and egg-laying chickens, Pekin ducks, and turkeys, and give a short overview of the key welfare issues. The focus is mainly on production systems in the United States, but similar systems are used in many other countries although they may be managed somewhat differently due to local differences in legislation, standards, availability or cost of resources (for example litter or feedstuffs), or markets. We note that, in the United States, there are no federal laws that regulate the animal welfare aspects of housing systems or production practices for poultry aside from the provisions included in the standards of the National Organic Program. Instead many producers follow voluntary animal welfare standards established by their industry trade organizations, and/or those of independent (third-party) certifiers (e.g., retailers, animal welfare labeling programs). Although the main focus of this chapter is on rearing and production systems for meat and egg-laying poultry, we briefly address some of the welfare concerns associated with breeding, hatcheries, and loading and transport. Detailed information about the welfare aspects of slaughter, euthanasia, and mass depopulation of poultry (when there is a serious disease outbreak, for example) can be found elsewhere in this volume (Lambooij and Hindle, Chapter 4; Linares et al., Chapter 7; McKeegan, Chapter 17; Vizzier-Thaxton, Chapter 5).

1.2 Meat birds

1.2.1 General aspects of housing and management

The rearing systems for broilers, turkeys, and ducks are quite similar. In general, meat bird production systems involve rearing birds indoors on a litter floor. The litter is typically wood shavings-based but straw, sand, rice hulls, and other materials may be used. Houses average 20,000 ft² (1858.1 m²) in area but stocking density varies depending on the type of meat bird being raised. The birds are placed in the house on the day of hatch (started) and provided with supplementary heat during the brooding phase, which may involve confining them to a portion of the house until they are better able to regulate their own body temperature. Automated drinkers and auger feed lines are used to deliver feed and water. Diets are phase fed, which allows for the requirements of the growing birds to be met during the different production phases.

Houses may have either tunnel ventilation or natural ventilation; in the United States, ventilation type depends on geographic location of the farm. Tunnel ventilation pulls the air through the house using inlets and exhaust fans while natural ventilation utilizes open-sided houses with curtains to control the amount of air flow. Lighting programs typically provide 23:1 light:dark for the first 7 days and then 20:4 for the remainder of the production period. However, there are many different kinds of lighting programs and the way the light is provided (e.g., lighting type, intensity, and long or intermittent blocks of light) can vary from one farm to another, and according to whether producers are following particular standards. Daily care entails walking the house at least once per day to collect mortality, identify health issues (Linares et al., Chapter 7), verify that feed, water lines, and other equipment (e.g., ventilation) are working appropriately, and check litter condition.

After the birds are sent to the processing plant, the producer prepares the house for another flock of birds. At a minimum this requires cleaning the feed and water lines, as well as removing large aggregates of litter and redistributing and conditioning the remaining litter in the house. For biosecurity reasons related to disease prevention, producers usually wait for 10 to 21 days before placing a new flock in the house. Some countries and certification programs have more stringent requirements for house preparation, for example, requirements to remove and replace all litter or to follow particular cleaning and disinfection protocols between flocks.

Below, we present an overview of the intensive systems that are the ones most commonly used for the commercial production of meat chickens, turkeys, and ducks. However, there is a small but growing segment of the industry in developed countries that raises meat birds in systems that range from semi-intensive to extensive. These include systems that provide the birds with outdoor access once they are past the brooding period (free-range) and systems where the birds are raised primarily outdoors (pasture-based systems or pond-based systems for ducks). Either free-range or pastured systems can be used for organic production, as long as they meet legal requirements (e.g., related to provision of organic feedstuffs and restrictions on the use of particular compounds for the prevention or treatment of disease). These systems tend to be quite variable in terms of their management and configuration, and producers may use atypical breeds, like Heritage breeds, that are better suited for outdoor rearing than typical commercial breeds or strains. Because of their variability, we will not attempt to describe these systems here, although some mention is made later about welfare concerns related to outdoor access for both meat and egg-laying birds, as well as organic production.

1.2.2 Broilers (meat chickens)

The USDA Agricultural Marketing Service defines four classes of meat chickens (Cornish game hen, Rock Cornish fryer or roaster, broiler or fryer, roaster) based on age, extent of keel bone (breastbone) calcification, and genetic stock (AMS, 2002). The industry, however, defines classes based on the size of the bird marketed (small to big), with days to market varying between 33 and 64 for the different sizes of birds. The difference in days to market is based on the final disposition of the carcass, i.e., as a whole bird, parts, or for the fast food or further processed product markets. Female and male chicks are usually raised together (referred to as straight-run rearing), but may sometimes be raised in separate houses (sex-separate). Fig. 1.1 shows a typical commercial broiler house during both the early and late rearing stages.

Figure 1.1 (A) Broiler chicks in a conventional house with alternating feed and water lines. Notice the plastic curtain in the background dividing the house to create a brooding area initially. (B) Broiler chickens close to market age in a tunnel ventilated production house.

In the United States, the standards of the National Chicken Council (NCC), which is the trade organization for broiler producers, recommend stocking densities varying from 6.5 to 9.0 pounds of live weight per 1 ft² (929 cm²) of house floor area (31.7–43.9 kg/m²) depending upon the desired market weight of the birds (NCC, 2017), whereas the European Union (EU) standards specify a range from 6.8 to 8.0 lbs/ft² (33–39 kg/m²) depending not only on bird size but on other aspects of management related to house air quality and thermal control (CEC, 2007). Daytime light intensities after the first week of the rearing period are typically kept very low, often less than 5 lx in the United States, although higher intensities are required in some countries (e.g., in the EU, where a minimum of 20 lx is required over 80% of the house throughout most of the production period) and for some certification programs. Drinking water is typically provided via nipple drinkers to help maintain the litter in dry condition.

When the birds are ready for market, the feed and water lines are hoisted to the ceiling, eliminating obstacles for the catch crew. Broilers can be caught by hand or by machine (e.g., chicken harvester or catching machine). With hand catching, the catch crew enters the broiler house and corrals the birds into a catching area. Transport containers are brought into the house and the crew hand-catches the birds and places them into the transport coops (crates). When each bank of coops is filled, it is placed onto the transport truck. If a catching machine is used, an individual controls the machine as it moves through the house. The machine uses a system of belts to move the broilers from the floor of the house to the transport coops. Each individual bird is weighed and when the desired total bird weight is reached for a particular coop, the belt is moved to the next coop. The number of broilers placed into each coop is dictated by bird size, ambient temperature during transport, and any third-party certifications that are being followed.

1.2.3 Turkeys

The USDA Agricultural Marketing Service defines two classes of meat turkeys (fryer-roaster and young) based on age and extent of keel bone (breastbone) calcification (AMS, 2002). The commercial industry classifies turkeys as heavy or light toms or hens. It takes 84 to 140 days for turkeys to reach target weights, depending on the sex of the young turkey (poult) and the time of year. The decision to produce a heavy or light bird depends on whether the turkey will be marketed as a whole bird or as further processed products. Toms and hens (males and females) are reared separately. Unlike the other meat birds, poults are brooded in a building that is separate from the production house, into which they are moved at around 6 weeks of age (Fig. 1.2). The brooder house is cleaned and disinfected between each group of poults.

Figure 1.2 (A) Turkey poults in a tunnel ventilated house with alternating feed and water lines. (B) Turkey toms close to market age in a naturally ventilated house. Source: Photograph of toms courtesy of Butterball LLC.

In the United States, stocking densities vary by third-party certification groups (Erasmus, 2017). Currently, while the National Turkey Federation (NTF), which is the trade organization for US turkey producers, does have turkey welfare standards (NTF, 2016), these do not include stocking density recommendations. Rather, densities are determined by other aspects of management related to house air quality and thermal control. Lighting programs and intensities are typically kept low, but beyond the requirement for a dark period (NTF, 2016) the actual lighting program (photoperiod and intensity) is determined by the individual companies. Drinking water is usually provided via bell waterers; however, some houses have nipple drinkers. The feeders consist of round feed pans that are filled via an auger system. Feeders and waterers are adjusted to the level of the birds’ back to eliminate feed and water wastage.

When the turkeys are ready for market, the feed and water lines are raised to the ceiling prior to loading the birds onto the truck. Turkeys are usually loaded by herding rather than being caught by hand. The turkeys are walked toward the loading area, where they are placed onto a conveyor system to move them out of the house and into the coop area on the transport truck. Several individuals slowly walk the birds toward the conveyor, ensuring a steady flow of turkeys onto the conveyor but not creating excitement which could cause the turkeys to pile at the conveyor system. At the top of the loader, workers drive the conveyor controlling the speed at which the turkeys are moved to the top of the conveyor and counting the number of birds placed into each transport coop.

1.2.4 Pekin ducks

Meat ducks are defined by USDA-AMS as two classes (broiler or fryer and roaster), with duck age and calcification of the bill and windpipe determining the classification (AMS, 2002). However, ducks are sent to market based on desired weight and disposition of the processed carcass (whole duck, parts, or further processed products). This results in ducks being processed between 38 and 45 days of age. We focus on Pekin ducks here because they are the main type of duck produced in the United States (and globally), but other types of ducks, e.g., Muscovy or Moulard (mule) ducks, may be produced for specific markets.

Pekin ducks are reared as mixed-sex flocks in three different types of rearing systems: litter floors, raised plastic flooring, or a combination of the two. Irrespectively, the ducklings are brooded in a smaller area of the production house where a higher temperature can be achieved for brooding. When the ducklings are around 3 weeks of age, the brooder area is opened up providing more area of the house for the ducklings to use. As they continue to grow, the entire house becomes accessible to them (Fig. 1.3). Currently, there is no trade organization in the United States that has standards for Pekin ducks.

Figure 1.3 Ducklings housed on raised plastic flooring with alternating feeders and water lines.

When it is time to send the ducks to the processing plant, the house equipment is lifted to make loading easier. As for turkeys, Pekin ducks are herded rather than hand-caught. The loading crew walks the ducks to the truck loading ramp. The ducks are counted as they are walked onto the ramp to ensure that the proper number of ducks is placed in each pen on the transport truck. Once a level of the truck is filled with ducks, a floor is lowered down to begin another tier of pens, with approximately six tiers on a truck.

1.3 Egg-laying chickens

Egg-laying hens have been selected to maximize egg production and egg quality traits; commercial strains lay about 250 to 310 eggs per year. Genetically speaking, there are two types of laying hens: white egg layers and brown egg layers. The hen genetic stock kept by a particular producer varies by region or location within the world, but is strongly driven by consumer preference for eggshell color or type of egg being produced, i.e., a shell egg or an egg for the liquid egg market. In some areas of the United States, for example, brown eggs can be sold for a premium while in other locations they cannot. There are a multitude of housing systems in use, spanning the extensive to intensive spectrum. An expanded section on each type of housing system can be found below. Each of the different housing systems requires a different level of management skill to ensure high levels of productivity while striving to optimize laying hen welfare within that system.

1.3.1 Pullets

Female chicks that have not laid an egg are referred to as pullets. The term pullet is used until approximately 18 weeks of age, at which point egg production begins. Pullets are reared in two major types of housing systems—brooding cages or litter brooding—or a hybrid of these (referred to in the United States as non-cage aviary pullet rearing). These rearing systems are shown in Fig. 1.4. For cage brooding, at around 4 weeks of age, half of the chicks are moved from their initial cage to another cage to provide them with additional room and access to resources until they are moved into the hen house at approximately 17 weeks of age. In a litter brooding environment, all chicks are placed on a littered floor, generally confined to an area of the house that can be adequately heated to help them maintain their body temperature. As they grow, the usable area of the house is expanded to provide additional space and resources. Finally, in a hybrid system, chicks are initially placed in a brooding cage, but at around 6 weeks of age are provided access to the floor. Both litter brooding and hybrid brooding allow the pullets to familiarize themselves with items such as perches, ramps, and/or ladders that are provided on the litter to help them navigate a complex environment, such as an aviary, in which they will be housed as mature layers.

Figure 1.4 Pullet rearing systems. (A) White layer pullets in a brooding cage. The water line (unseen) is inside the cage while the feeder is located externally. (B) Brown layer pullets in a cage-free pullet rearing facility. The feeder and water line are both internal providing a perch for the pullets. The chicks will be provided access to the litter area at approximately 6 weeks of age. (C) Brown layer pullets in a cage-free pullet rearing facility. The brooding cages have been opened, providing the pullets with access to the litter area. Ramps and perches are installed to allow pullets to more easily navigate the house.

Pullets are fed a diet that is nutritionally formulated based on the primary breeder’s management guide. Daily care entails walking through the pullet house identifying mortality and birds that appear unhealthy, as well as checking feed and water lines to ensure there are no malfunctions. A vaccination program developed with a veterinarian that entails both spray vaccines and injections is used throughout the first 13 weeks of life. A typical pullet lighting schedule starts with 24 hours of light, decreasing to 22 hours of light by 7 days of age between 5 and 10 lx, with an illumination level between 5 and 10 lx. Producers then continue to decrease the photoperiod, achieving 8–10 hours of light by 7 weeks of age. Pullets are then maintained on this photoperiod until they are moved into the hen house, at approximately 18 weeks of age.

1.3.2 Laying hens—General aspects of production and management

A laying farm may be in-line or off-line with respect to how the eggs are handled. A farm where the eggs are produced in the house, placed on egg flats, stored in a cooler, and moved to a separate egg processing facility is considered off-line. If the eggs produced at the farm travel on conveyor belts to a central egg processing plant located at that farm, then it is considered to be in-line. At an in-line farm, the feed mill, production houses, and egg processing plant are all at the same location. The feed mill is connected via an auger system to each house and delivers unique diets to the external feed bins located at that house. An off-line farm has a central feed mill and the diets are trucked to each farm. An in-line or off-line laying farm may have either one house or multiple houses. Houses vary in size, but a single house typically contains 50,000–200,000 hens. Each house contains hens of the same age, and houses are staggered in terms of hen age to ensure a consistent egg supply while allowing for an all-in-all-out biosecurity approach in each house. A laying farm may continue to grow over time by increasing the number of houses, which increases the number of eggs produced at a single location.

Similar to meat birds, important aspects of laying hen management are nutrition, lighting, and daily care. Laying hen nutritional needs are well established from research conducted over the past 75 years. Laying hens are fed phase diets that are formulated to meet the requirements of the hen’s productive status throughout the lay cycle. Typically, around 6 different diets are fed from 17 weeks of age to the end of the production cycle at approximately 85 weeks of age. The diets change based on egg production percentage, egg size, and feed consumption to ensure a high level of performance and that the desired egg size is maintained. When the pullets are placed in the house the photoperiod is increased from about 10 hours of light per day to 16 hours over a period of several weeks, where it is then maintained until the end of the production cycle. Daily care entails walking through the laying house identifying mortality, checking feeders and drinkers, collecting floor and system eggs (depending on the housing system), and observing flock health (Linares et al., Chapter 7).

The predominant laying hen housing system in the United States and globally has been the conventional cage for more than 60 years. However, the increased consumer interest in many countries in how food is produced, and the desire to address emerging animal welfare concerns by providing the hens with more behavioral opportunities, has moved the industry toward other production systems. These production systems can be viewed as varying on the intensive to extensive spectrum: enriched colony cage (also called a furnished cage), aviary, barn, free-range, pasture, and organic.

1.3.2.1 Conventional cage

The conventional cage system has transitioned over the years from high-rise houses with A-frame caging to stacked, belted caging (Fig. 1.5). Cages vary in size, but typically hold 5 to 10 hens. In the United States, under the animal welfare standards of the trade organization of the egg producers, United Egg Producers (UEP), hens are given a minimum floor space allowance (stocking density) of 67 in² (432.3 cm²) per hen (UEP, 2017). Other countries may require different minimum stocking densities, as may the certifying bodies and egg buyers (e.g., restaurants, grocery stores, and food service) that set independent standards for egg production. A conventional cage has a nipple or cup drinker and a feed trough in front of the cage. Feed and water are delivered automatically to provide free access for the hens. The cage floor is sloped, allowing for eggs to roll to the front of the cage onto the egg belt, at which point the eggs are conveyed on multiple egg belts to the processing area.

Figure 1.5 A conventional cage house stocked with white laying hens. The water lines are located inside the cage while the feeder runs on the outside of the cage front. This stacked belted system has a manure belt between each tier to remove excreta while an egg belt moves the eggs in the opposite direction toward the processing plant.

1.3.2.2 Furnished or enriched colony cage

Furnished cages were developed in Europe in the early 2000s in an attempt to address concerns about the behavioral restriction imposed by conventional cages, which were banned in 1999 (with the ban effective 2012) in the EU. Initially, furnished cages were small cages similar in size and shape to conventional cages, but containing a perch, nest box, and a litter area for scratching and foraging. Over time the cages were enlarged, and the cage features became more standardized across cage manufacturers. These new larger systems, which house 60 to 100 hens per cage, are often referred to as enriched colony cages (Fig. 1.6).

Figure 1.6 An enriched colony cage stocked with white laying hens. The enriched colony cage provides perches (A), a nesting area surrounded by plastic curtains with a nest mat (B) and a scratch pad (not seen). In this system, the water lines are inside the cage while the feeders run outside the cage on both sides; some designs of enriched colonies also have internal feeders.

The colony cage currently in widest use by the commercial industry is approximately 5 ft (152.4 cm) wide by 12 ft (365.8 cm) long with a nesting area, perches, and a scratch pad. Hens are provided with at least 116 in² (748.4 cm²) of floor space per hen. The nesting area consists of plastic flaps that hang around a nest pad (usually made of Astroturf or rubber coated wire). The perches are located in the center of the cage and, depending on the cage manufacturer, may be made of molded plastic or metal and may be either square or cylindrical in shape. The scratch pad area is located at the opposite end of the cage away from the nesting area. Scratch pads vary in size and materials used, including Astroturf, heavy plastic sheets, and molded plastic. There may be claw abrasive strips (nail file bars) positioned close to the feed trough. Multiple nipple drinkers and feed troughs (typically two external feed troughs, one on each side of the cage) provide automatically delivered feed and water. Depending on the cage design, to encourage foraging behavior there may be an internal auger that drops feed on the scratch pad or there may be holes in the external auger that distribute feed onto a small area in the cage close to the feed trough. The cage floor is slightly sloped so eggs will roll onto the egg belt, with the fate of the eggs the same as for the conventional