Engormix/Poultry Industry/Technical articles

On-Farm Welfare Assessment: Broilers

Published on: 5/10/2022
Author/s : Hayley Sutherland, Purdue University; Dr. Marisa Erasmus, Purdue University. Reviewers: Dr. Prafulla Regmi, University of Georgia; Dr. Leonie Jacobs, Virginia Tech; Dr. Shawna Weimer, University of Maryland.
On-Farm Welfare Assessment: Broilers - Image 1
In 2020, the poultry industry had a combined value of over $35.5 billion in the United States. Of that, $21.7 billion came from broiler chicken production (USDA-NASS, 2021). Over 9.22 billion broiler chickens were raised and brought to market though the year, making it the largest and most valuable sector of U.S. poultry production. With such a massive impact, it has become increasingly important to monitor the welfare of these broilers. Advancements over the last 100 years have allowed us to develop faster growing broilers, which reach market weight within 42 days of age. A shorter growing period allows for more birds to be reared throughout the year, which keeps up with demand and our growing population. As we have seen with egg laying hens, there has been increased public interest in animal welfare. However, broilers face different challenges compared to laying hens.
In order to assess welfare of the broilers, various tools and measurement systems have been developed. Animal data, as well as environmental data, are collected and analyzed to better understand what issues broilers face during rearing and what can be done in the future to resolve them.
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Environmental Factors
Inside the barn, we can collect information about the environment, such as the air quality, temperature, relative humidity, and litter condition.
Air quality - Ammonia
- Ammonia (NH3) is a gas that is toxic to both humans and poultry. Ammonia is found in excrement from broilers. Ventilation in the barn is important to keep levels low.
- Guidelines state that levels should be below 25ppm (National Chicken Council, 2017).
- Ammonia levels are affected by litter condition (see below)
- Commercial broiler strains have guides that dictate overall barn temperature during each stage of development.
    * See Cobb Vantress or Aviagen Ross 708
- Broilers require high temperatures during brooding, as they cannot self-regulate temperature yet. Young broilers can become hypothermic and die if they are not adequately warmed. Recommended temperatures during the first 7 days of age are between 81-86°F.
- As broilers get older, the overall barn temperature decreases. House temperatures at market weight are about 68°F.
- Poor ventilation combined with higher stocking density can cause heat stress and result in decreased feed consumption, as well as decreased body weight (Kang et al., 2019).
- When heat stressed, broilers will perform cooling behaviors, such as panting, gular fluttering, and wing spreading
- When cold, broilers will huddle together and tuck their wings close to their bodies.
Relative Humidity
- Humidity and temperature form the heat index.
- At a constant temperature, increasing humidity levels will increase the heat index. This makes the room feel hotter than what the thermometer reads.
- Humidity can be measured using a hygrometer, where results are displayed as a percentage (%) of water vapor present in the air.
Litter Condition
- This is an environment-based measure found in the Welfare Quality Protocol for Poultry.
- Litter condition directly impacts footpad, hock, and feather cleanliness conditions.
- Poor litter quality joined with high relative humidity can cause increased ammonia levels.
- Litter is scored using the following scale:
    * 0 = completely dry and flaky, i.e. moves easily with the foot
    * 1 = dry but not easy to move with foot
    * 2 = leaves imprint of foot and will form a ball if compacted, but ball does not stay together well
    * 3 = sticks to boots and sticks readily in a ball if compacted
    * 4 = sticks to boots once the cap or compacted crust is broken
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Fear Tests
There are several tests that can be used to assess different fear responses. We can look at fear of people using a stationary person test. We can use a novel object test to assess their fear of something new. The following tests have been adapted from the Welfare Quality Protocol for Poultry.
Stationary Person Test
- To perform a stationary person test, an assessor will enter a barn and randomly select a location in the barn to stand at.
- For two minutes, the number of broilers within 0 to 1 meter (0 to 3.3 feet) and 1 to 2 meters (3.3 to 6.6 feet) of the assessor's feet will be recorded. Number of broilers will be recorded every 20 seconds.
- For example, having 10 broilers within 0-1m at 20 seconds into the test could mean less fearfulness, or lameness issues. If a bird cannot walk, it will not move, or be unable to move very far within the first 10 seconds of the test.
- This test should be performed along with gait scoring to make the distinction
Novel Object Test
- To perform a novel object test, a novel object must be developed. One way is to take a 1 foot long wooden dowel and wrap it in 3 to 4 different colors of tape. Broilers can see colors and it will provide a bright contrast to other components in the barn.
- Place the novel object on the ground and stand at least 3 meters (9.8 feet) away.
- For two minutes, the number of broilers within 0 to 0.5 meters (0 to 1.6 feet) of the novel object will be recorded. Number of broilers will be recorded every 10 seconds.
- For example, having an increasing number of birds approach during each 10 second interval would show less fearfulness and increased curiosity.
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Low-Stress Handling
Proper handling of the broiler is important when assessing welfare. If the broiler does not feel supported, they are likely to struggle and flap their wings. This can cause lost grip and can result in injury for the broiler.
Broilers should not be lifted by only by the legs, and causes them stress if they are held upside down. For more information on the safe handling of broilers, visit this publication by the Humane Slaughter Association.
It is good practice to handle a bird with both hands. Support under them with one hand, while using your other hand for additional restraint or holding out the feet as seen in the image on the left. Also, holding them against the side of your body will reduce struggling and wing flapping, keeping the bird secure and balanced.
Then, it is easy to view both the hocks (blue circles) and the footpads (red circles).
Gait Scoring
One of the most helpful welfare assessment tools for broilers is gait scoring. Leg health problems are common in broilers (read about them in PEC's non-infectious leg health issues here); therefore, assessing their walking ability is important.
Repeated scoring could be used to keep track of lameness in a flock, and identify time points to take action. Broilers should take at least 3 consecutive steps in order to determine their gait score.
The following 6-point system is from the Welfare Quality Protocol for Poultry.
0 = normal, dextrous, agile
1 = slight abnormality, but difficult to define
2 = definite and identifiable abnormality
3 = obvious abnormality, affects ability to move
4 = severe abnormality, only takes a few steps
5 = incapable of walking
To view videos of the 6-point system, please click here.
A simplified 3-point system can also be used (Webster et al., 2008).
0 = bird can walk at least 5 ft with a balanced gait. Bird may appear ungainly but with little effect on function
1 = Bird can walk at least 5 ft but with a clear limp or decidedly awkward gait
2 = Bird will not walk 5 ft. May shuffle on shanks or hocks with assistance of wings. After gait scoring, broilers can be picked up and handled for further assessment.
The following animal-based measures (footpad dermatitis, hock burn, and feather cleanliness) are all found in the Welfare Quality Protocol for Poultry.
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On-Farm Welfare Assessment: Broilers - Image 6
Recommendations for broiler chicken welfare assessment
When and how often?
- It is good practice to assess broiler welfare as often as is practical. Risks to broiler chicken welfare increase as birds get older; therefore, it is good practice to assess welfare at least once a week from 4 weeks onward.
How many birds?
- For large commercial flocks, the Welfare Quality Protocol for Poultry recommends assessing 10 birds from each of 10 locations within the barn.
To ensure consistency and accuracy, all personnel performing the assessments should be trained. In addition, proper record keeping will enable welfare status to be monitored and maintained.
On-Farm Welfare Assessment: Broilers - Image 7
This article was originally published on Poultry Extension Collaborative (PEC) and it is reproduced here with permission from the authors. 

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