Interpretive Summary: How mites influence cage-free egg production in the United States, mite management strategies, and the mitigating role of genomic selection

By: Jacqueline A Holquinn, Hayley L Sutherland, Elaina R Sculley, Marisa A Erasmus, Luiz F Brito, Amy C Murillo

• The US poultry industry is significantly increasing cage free egg production, which is providing opportunities for ectoparasitic mites.
• Ectoparasites negatively impact hen welfare, including hen health, behavior, and productivity, and mite management strategies are lacking.
• There is evidence of genetic variability for mite resistance and genomic selection could offer a feasible alternative for improving mite resistance in purebred and crossbred poultry populations.

Egg production in the United States has changed significantly in the last century. From the 1920s to the 1960s, egg production underwent a significant evolution, driven by advancements in breeding and husbandry practices (Kidd and Anderson, 2019). In the early 20th century, chickens were typically raised on small farms, where they were valued for both egg and meat production. However, during this period, there was a shift toward industrialization of poultry farming (Kidd and Anderson, 2019). Innovations in housing, feeding, and disease management contributed to improved efficiency and productivity within the egg industry. By the 1960s, the adoption of intensive farming methods, including the use of conventional or “battery” cages, had become widespread, dramatically increasing the scale of egg production, and setting the stage for modern commercial poultry farming practices (Kidd and Anderson, 2019). However, a growing sector (approximately 40%) of the egg industry is adopting cage-free housing for over 124 million laying hens as consumer demand for improved animal welfare increases and some state legislation requires more space per bird. There has also been an increase in certified organic egg production, which by definition is cage free; there are over 27.5 million organic laying hens raised in the US annually (USDA-NASS, 2021). The switch from cage-to-cage-free production provides hens with more behavioral opportunities, but some risks to hen health are more prevalent in cage free systems (Lay et al., 2011). In particular, the switch to cage-free housing is significantly impacting the prevalence of ectoparasites such as the northern fowl mite (Ornithonyssus sylviarum) and poultry red mite (Dermanyssus gallinae) in poultry facilities (Murillo and Mullens, 2016; Chambless et al., 2022). Mite infestations impact all areas of hen welfare, including hen health, behavior, productivity, and emotional state. Here, we discuss what is known about northern fowl mites and poultry red mites, their impact on hens; current mite management strategies and challenges, and the potential for using genomic tools to manage mites in US cage-free egg production.

Read the full article in Animal Frontiers.