Effects of the poultry red mite (Dermanyssus gallinae) load on the plumage condition in commercial laying hen farms

Abstract

Plumage damage (PD) resulting from severe feather pecking (SFP) is a significant problem for animal welfare, performance, and economics in commercial laying hen farms. Genetics, nutrition, and housing conditions are central complexes that contribute to the multifactorial cause of SFP. Practical experience suggests that infestation by the poultry red mite (PRM), which is the most severe ectoparasite of laying hens in cage-free housing systems, may be a risk factor for the occurrence of PD, although evidence-based findings are lacking. The objective of this longitudinal observational field study was to investigate the effects of PRM infestation of commercial laying flocks on the occurrence of PD. Integument scoring (plumage damage and skin lesions) and the quantification of PRM infestation using mite traps were conducted during the laying period of 28 laying flocks, with an average flock size of 12,357 birds in barn (n = 21) or free-range (n = 7) systems. Across all flocks and survey times, the median PRM mass per trap was 0.7 mg (1.-3. quartile: 0.0–19.3 mg/trap), corresponding to a median count of 65.2 mites/trap (1.-3. quartile: 0.0–246.8 mites/trap). Binary logistic regression models revealed an association between PD and skin lesions with hen age, housing system, and hybrid type (p<0.001). The PRM load also affected the plumage condition, where PD increased with increasing PRM infestation (p<0.001). In addition, the PRM load tended to have an effect on skin injuries (p = 0.097). In conclusion, this longitudinal study identified the PRM load in laying hen flocks as a risk factor for PD.

Perception of laying hen farmers, poultry veterinarians, and poultry experts regarding sensor-based continuous monitoring of laying hen health and welfare

“…Self-assessed infestation rates on commercial laying hen farms differ from mite trap-based infestation rates ( Waap et al, 2019 ), resulting in underestimation of infestation load. Schreiter et al (2022) identified PRM load as a risk factor for severe FP. In our study, FP was appointed as the most relevant health and welfare problem in hens housed in aviaries by poultry experts.…”

Spatial Distribution of Dermanyssus gallinae Infestations in Greece and Their Association with Ambient Temperature, Humidity, and Altitude

“…Specifically for industrial poultry houses using enriched cages, stacking them on top of each other, and creating multiple floors, the traps were placed on different rows (sides to middle) and floor levels (high, medium, low) at equal distances from one another, beginning from the entryway until the opposite side. Placement spots included perches, particularly the higher ones in aviary systems, under the egg conveyor belt, metal connections, under feeders, under watering lines, and grates/slats in or near nests in backyard poultry farms [ 5 , 27 , 31 , 35 ]. The traps were secured using ten black cable ties (thickness of 2 mm, length of 200 mm), which accompanied each set of 10 traps.…”