For a long time, poultry mite infestations have been associated with irritation and discomfort, feather damage, and production losses in laying hens.
However, growing evidence suggests that their impact goes far beyond this, also affecting bird behavior, stress levels, and overall welfare.
In this interview, Bill Vaughn, MBA, Associate Director of Poultry Marketing at MSD Animal Health, discusses research into the underestimated effects of mite infestations on animal welfare, and how new management and treatment approaches can help producers address mite infestations more effectively.
How has the poultry industry viewed mites in the past?
Traditionally, mites have mainly been seen as a nuisance or a problem affecting production.
Farmers know that mite infestations can affect the condition of chickens and may affect production performance, but their impact on animal welfare may not have received the same level of attention.
More recent research, including studies conducted under commercial layer-hen housing systems, has helped us recognize that mites cause significant stress to chickens.
Its effects go beyond irritation and discomfort.
Chickens remain in a state of discomfort, which affects their behavior and overall condition.
How do mites affect chickens?
One of the clearest findings concerns nighttime behavior.
Researchers in multiple countries used night-vision cameras to assess the activity of flocks infested with poultry red mites and flocks without parasites.
The nighttime activity of mite-infested hens increased significantly, while hens usually rest at night.
Other studies involving *Ornithonyssus sylviarum* and poultry red mites also recorded physical indicators associated with poorer welfare, including comb wounds, skin lesions, and feather-condition problems.
One study found that skin lesions improved after *Ornithonyssus sylviarum* was eliminated; the lesions reappeared when infestation recurred.
The study also evaluated physiological stress indicators, including corticosterone levels, blood biochemical indicators, and hematological indicators.
Overall, these findings suggest that mite infestation can trigger a measurable stress response and adversely affect the welfare of chickens.
Figure 1. A chicken wearing a plastic “backpack” containing an activity sensor (a triaxial accelerometer) (left). Plastic housing for the activity sensor (right).
Why is it important that nighttime behavior is disturbed?
Rest is essential for chickens.
When mites feed on hens at night, the chickens become more restless and agitated.
More scratching, preening, and signs of general discomfort can be observed.
Over time, chronic stress affects the overall condition of the flock and may also affect production performance.
For severely parasitized chickens, producers may also notice pale combs associated with blood-loss anemia.
Does the industry underestimate the impact of mites on animal welfare?
Yes, I believe this impact is underestimated.
Based on what I have heard from some people who have worked in the laying hen industry for many years, farmers often know that their flocks have mites but prioritize other issues, as they may not believe the mites are serious enough to significantly affect production performance or bird health.
The industry is now paying increasing attention to bird welfare and body condition, but parasite problems may still not receive the same level of attention as some other welfare issues, even though research has clearly shown that these parasites cause measurable stress and welfare impacts.
What changes do farmers notice after successful treatment
Farmers can see mites on the birds, so they know that a mite infestation is present.
Workers have even described the sensation of being bitten by mites, although poultry red mites do not live on people the way bed bugs do.
After effective treatment, farmers may soon see the number of mites on their chickens decrease or disappear, while the chickens’ condition and behavior also improve.
Why has traditional mite control been challenging?
Many traditional methods rely on sprays, dusts, or other environmental treatments. These methods may require considerable labor and can be difficult to apply consistently throughout an entire commercial poultry house.
Some methods require staff to wear more personal protective equipment during application.
Other methods rely on environmental contact to act on mites and may be less direct or effective than systemic methods that target mites feeding on the chickens.
Are management practices changing?
Yes. Today, farmers can use some newer methods that may offer practical operational advantages compared with some traditional treatment methods.
For example, Exzolt (fluralaner oral solution) was recently approved in the United States for the treatment and control of northern fowl mites in laying hens and pullets.
Because it is administered through drinking water, it can simplify administration and reduce labor compared with some spray or dusting methods.
Because northern fowl mites live on chickens and feed on their blood, systemic treatment administered through drinking water can directly target mites that are feeding.
At the same time, producers still need to strengthen monitoring, detect infestations early, and maintain overall flock management.
If mite infestation is not detected early, any treatment plan will have difficulty achieving good results.
What impact does it have on production performance?
Field experience shows that successful mite control helps maintain production performance. However, some of these observations are still being compiled and published.
Animal welfare and production performance are interrelated.
Chickens experiencing chronic stress over a prolonged period typically cannot achieve their best production performance.
In addition, compared with earlier spray or dusting control methods, some newer treatments can reduce labor requirements.
What do you hope producers will take away from these studies
Mites are more than just a nuisance; they can significantly affect the comfort and welfare of chickens and the overall condition of the flock.
Encouragingly, compared with the past, poultry producers now have more options for managing infestations of poultry red mites.
Combined with monitoring and early intervention, these tools help safeguard chicken comfort, welfare, and flock performance.
Note: This article is reproduced from the Modern Poultry website. By Bill Vaughn, vice president of poultry marketing at Merck Animal Health, MBA.