How to choose which birds to assess:
General Sampling
Currently, there is no consensus on the best way to sample large flocks of laying hens for animal-based measures of welfare. Although researchers are working to figure out this issue, questions remain on the correct number of hens to sample, where to sample hens within a particular housing system, and how to deal with potentially over- or under-sampling measures.
Methods of Sampling
There are two common methods of sampling that can be used when assessing hens for these measures. The first is "catch and release". As the name implies, this method entails catching individual hens one at a time, assessing them for the measures, and then releasing them back into the flock. While this technique allows for the most detailed assessment, it can be labor and time intensive. Birds that are sick or injured may also be hiding within a system, and therefore under-sampled, or they may be very easy to catch and over-sampled for a flock. The second method is called the "transect method". This method entails walking the length of a building in pre-determined transects and assessing hens as the observer walks. This method does not rely on catching birds, therefore, it requires less labor and time to conduct. However, the optimum number of transects needed to assess a flock is unknown. This method has not been validated for laying hens, although it does show promise in turkey and broiler flocks. This method may also miss some detailed measures that may be important. As you go through this website, the most appropriate method of sampling is given for each measure.
Choosing Birds to Sample
The number of birds that should be sampled to represent a flock is unknown. If you are auditing a farm, you should follow the auditing tool guidelines for the number of hens to sample for any given measure. Guidance from the auditing company should be sought if guidelines are not provided. As there are many types of housing systems with varying degrees of complexity and access to the outdoors, where the birds are sampled from should be considered. As much as is possible, birds should be sampled from all areas of a housing system. For example, if there are multiple levels within a house, such as a raised slatted floor or aviary, birds from all levels should be sampled from the litter upwards. If the birds have outdoor access, be sure to sample birds from inside and outside. As with indoor systems, sample birds from all outdoor areas as much as possible.
Timing of Sampling
Time of sampling both within a day and throughout a flock's life can have implications on the measures taken. Entering the house can be a stressful event for the laying hens. As the birds are typically disturbed, especially if using the catch and release method, it is often best to sample at a cooler part of the day. This usually means sampling in the morning. It is important to note that most hens are in the process of laying eggs in the morning, and disturbance at that time can lead to injury and egg-related problems such as peritonitis. Producers can be asked for their input on the best time of day to sample. The condition of laying hens also changes over the life of the flock, and many animal-based measures will vary in their occurrence and severity as hens age. For instance, feather cover typically declines and keel bone abnormalities generally increase as hens age. Therefore, it is important to note the age of the flock being sampled, and any changes that may be occurring if the flock is sampled multiple times.
It is also important to make a note about fear behavior of laying hens. Hens are inherently fearful of humans, although they readily habituate to people they see on a regular basis. As an auditor, you are likely new to the birds, and probably wearing person protective equipment that the birds are not regularly exposed to. This has the potential to cause hens to panic when you enter the house, which can cause piling at the opposite end due to birds trying to escape. Piling can lead to smothering on a large scale. You should always enter the house with the producer or staff entering first. Slowly walk into the building, and allow the birds some calming time (about 5 - 10 minutes) to get used to having a new person in the house. If they show fear behavior, always stop and wait until the birds are calm. If the birds panic frequently during sampling, you may want to consider not sampling that flock if piling is likely to occur.
Currently, there is no consensus on the best way to sample large flocks of laying hens for animal-based measures of welfare. Although researchers are working to figure out this issue, questions remain on the correct number of hens to sample, where to sample hens within a particular housing system, and how to deal with potentially over- or under-sampling measures.
Methods of Sampling
There are two common methods of sampling that can be used when assessing hens for these measures. The first is "catch and release". As the name implies, this method entails catching individual hens one at a time, assessing them for the measures, and then releasing them back into the flock. While this technique allows for the most detailed assessment, it can be labor and time intensive. Birds that are sick or injured may also be hiding within a system, and therefore under-sampled, or they may be very easy to catch and over-sampled for a flock. The second method is called the "transect method". This method entails walking the length of a building in pre-determined transects and assessing hens as the observer walks. This method does not rely on catching birds, therefore, it requires less labor and time to conduct. However, the optimum number of transects needed to assess a flock is unknown. This method has not been validated for laying hens, although it does show promise in turkey and broiler flocks. This method may also miss some detailed measures that may be important. As you go through this website, the most appropriate method of sampling is given for each measure.
Choosing Birds to Sample
The number of birds that should be sampled to represent a flock is unknown. If you are auditing a farm, you should follow the auditing tool guidelines for the number of hens to sample for any given measure. Guidance from the auditing company should be sought if guidelines are not provided. As there are many types of housing systems with varying degrees of complexity and access to the outdoors, where the birds are sampled from should be considered. As much as is possible, birds should be sampled from all areas of a housing system. For example, if there are multiple levels within a house, such as a raised slatted floor or aviary, birds from all levels should be sampled from the litter upwards. If the birds have outdoor access, be sure to sample birds from inside and outside. As with indoor systems, sample birds from all outdoor areas as much as possible.
Timing of Sampling
Time of sampling both within a day and throughout a flock's life can have implications on the measures taken. Entering the house can be a stressful event for the laying hens. As the birds are typically disturbed, especially if using the catch and release method, it is often best to sample at a cooler part of the day. This usually means sampling in the morning. It is important to note that most hens are in the process of laying eggs in the morning, and disturbance at that time can lead to injury and egg-related problems such as peritonitis. Producers can be asked for their input on the best time of day to sample. The condition of laying hens also changes over the life of the flock, and many animal-based measures will vary in their occurrence and severity as hens age. For instance, feather cover typically declines and keel bone abnormalities generally increase as hens age. Therefore, it is important to note the age of the flock being sampled, and any changes that may be occurring if the flock is sampled multiple times.
It is also important to make a note about fear behavior of laying hens. Hens are inherently fearful of humans, although they readily habituate to people they see on a regular basis. As an auditor, you are likely new to the birds, and probably wearing person protective equipment that the birds are not regularly exposed to. This has the potential to cause hens to panic when you enter the house, which can cause piling at the opposite end due to birds trying to escape. Piling can lead to smothering on a large scale. You should always enter the house with the producer or staff entering first. Slowly walk into the building, and allow the birds some calming time (about 5 - 10 minutes) to get used to having a new person in the house. If they show fear behavior, always stop and wait until the birds are calm. If the birds panic frequently during sampling, you may want to consider not sampling that flock if piling is likely to occur.