Research Note: Dynamics of black grouse (Tetrao tetrix) infestation with various Eimeria species.

The black grouse (Tetrao tetrix) is an endangered species facing challenges in breeding and reintroduction programs, including parasitic infestations. This study aimed to assess natural infestations by various Eimeria species and infestation dynamics in female, male, and young black grouse kept in a stationary aviary. Faecal samples were collected from adult grouses between April and the time of chicks' hatching and rearing (September). Faecal samples from young birds were collected from the hatching for a period of 1 year. The prevalence of Eimeria spp. was determined by a qualitative method (Fulleborn's flotation) and a quantitative method (McMaster's method with Raynaud's modification). The following Eimeria species were identified: E. lyruri, E. nadsoni and E. nonbrumpti. The average percentages of Eimeria spp. in the cock were 80.52%, 9.27%, and 10.21%, respectively; in the hen, they were 86.19%, 9.28%, and 4.53%, respectively; in the young black grouses they were 84.60%, 9.34% and 6.06%, respectively. The highest E. lyruri infestation was observed in the cock in June (144227 OPG) and July (129365 OPG). In the hen, the infestation intensity increased in May (304302 OPG) and then decreased in June (39583 OPG). Furthermore, an additional increase was observed in July (216533 OPG). Two increases in infestation intensity were also observed in young birds, with peaks in January (91387 OPG) and July (126178 OPG). A positive strong correlation was identified between Eimeria spp. in the cock and the young birds. A statistically significant positive correlation was identified in the hen between E. lyruri and E. nadsoni. No correlation was demonstrated between the infestation intensity and the age of the birds or season of the year in all the grouses under study. Despite some attempts, a comprehensive approach to the issue of coccidiosis in the black grouse as a disease that may affect the success of reintroduction has yet to be established. It seems crucial to monitor the level of Eimeria spp. invasion, and the proposed faecal sampling scheme is an important tool for achieving this goal.

Genetic Characterization of the Poultry Red Mite (Dermanyssus gallinae) in Poland and a Comparison with European and Asian Isolates.

(1) Background: The blood-feeding mite Dermanyssus gallinae (De Geer 1778) continues to attract wide interest from researchers and bird breeders. The aim of this study was to evaluate the genetic diversity of D. gallinae populations in five commercial laying hen farms in Poland and to determine their similarity with isolates from other countries. The study involved an analysis of a fragment of the cytochrome c oxidase subunit I gene (COI). A total of 38 isolates obtained from Polish farms and 338 sequences deposited in GenBank were analyzed. (2) Results: Haplotype No. 46 was dominant (90%) in Polish isolates and was homologous with the isolates from Great Britain, the Netherlands, Belgium, Japan, and South Korea. These results are indicative of high genetic homogeneity and common ancestry of the poultry red mite and point to a common source of infestation in the examined farms. (3) Conclusions: The genetic diversity of D. gallinae should be further studied to promote a better understanding of how this parasite is disseminated within and between countries.

An in vitro evaluation of the sensitivity and responses of Dermanyssus gallinae to selected acaricides.

Dermanyssus gallinae is an obligatory ectoparasite of birds which feeds on blood and significantly compromise the well-being of commercially raised laying hens. In this study, the mortality rates and responses of D. gallinae to 2 acaricides with a physical mode of action (Dergall and Mite Max) and 2 acaricides with a chemical mode of action (Milben Ex and Bio PK) were evaluated in tree dilutions (S1-3) and compared at 8-time intervals after application. The evaluation involved a novel method that simulates real-world conditions in a commercial poultry farm. Tested products have shown high efficacy (84.3-100%) against D. gallinae in the producer recommended solution (S1). Acaricides with a physical mechanism of action were as effective as chemical agents in eradicating poultry red mites. The compared preparations differed only in the onset of action which was longer in acaricides with a physical mode of action (1-6 h for chemical 24 h for physical in S1). An increase in the concentration of the active ingredient did not significantly speed up the onset of action of the evaluated preparations. However, the efficacy of Dergall and Bio PK decreased when the applied dose was halved, to 12% and 0% respectively. A decrease in the dose Mite Max led to a somewhat smaller, but not statistically significant decrease in mite mortality rates (74%). The proposed method for evaluating acaricide efficacy can be helpful in selecting the most effective preparations and the optimal concentration of the working solution to be applied in commercial layer farms, thus reducing the costs associated with the eradication of D. gallinae. The developed method enables a reliable evaluation of acaricides with both a physical and chemical mode of action, and it supports observations of the parasites' responses to the applied treatment.

Changes in the Percentages of B- and T-Lymphocytes and Antibody Titres in Laying Hens Infested with Dermanyssus gallinae-A Preliminary Study.

(1) Background: Dermanyssus gallinae, a hematophagous ectoparasite, adversely affects the health status of laying hens, leading to reduced egg production and significant economic losses in commercial farms. The aim of this study was to determine the effect of D. gallinae on the development of post-vaccination immune responses in layer hens. (2) Methods: A total of 80 blood samples were collected at four time-points (B1-B4) from 10 Hy-Line Brown hens, randomly selected from a commercial layer farm. The flock was naturally infested with D. gallinae and treated twice with Biobeck PA 910 (AI silicon dioxide). The samples were collected before and after each treatment. The percentages of IgM+ B cells, CD3+/CD4+ T cells and CD3+/CD8a+ T cells were determined by flow cytometry; the titres of antibodies against avian encephalomyelitis, infectious bronchitis virus, Newcastle disease virus, Ornithobacterium rhinotracheale, reticuloendotheliosis virus and avian reovirus were determined by the immunoenzymatic method. (3) Results: The percentage of Th cells and post-vaccination anti-IBV and anti-NDV antibodies decreased significantly at the second infestation peak when the number of parasites was twice higher than at the first infestation peak. Non-significant negative correlations were found between the number of mites and the percentage of B cells (R = -0.845, p > 0.05) and between the number of mites and the percentage of Th cells (R = -0.522, p > 0.05), and a significant positive correlation was noted between the number of mites and the percentage of Tc cells (R = -0.982, p < 0.05). There were non-significant correlations between the number of mites and antibody titres. (4) Conclusion: The present findings suggested that D. gallinae might inhibit immune responses since the percentages of B cells and Th cells were negatively correlated with the number of mites. The percentage of Tc cells was positively correlated with the number of mites, which indicated that D. gallinae could stimulate cellular immune responses in infested laying hens. However, further research is needed to determine whether D. gallinae suppresses the production of vaccine-induced antibodies.

The influence of Dermanyssus gallinae and different lighting regimens on selected blood proteins, corticosterone levels and egg production in layer hens.

Egg production in battery cage systems in commercial poultry farms promotes uncontrolled growth of poultry ectoparasite Dermanyssus gallinae. Intermittent lighting regimens provided a promising alternative for controlling D. gallinae invasions. The study analysed the influence of D. gallinae invasions on selected blood protein fractions (albumin, α-, ß-, γ-globulin), corticosterone levels and egg production in Hy-Line Brown layer hens exposed to two lighting regimens: A (16 L:8D) and B (intermittent (4 L:2D); L-light, D-dark). Blood samples were collected from a total of 48 hens (divided into uninfested - UF, and infested - IF groups for each lighting regimen). The concentrations of protein fractions were analysed by electrophoresis on Cormay Gel Protein 100, and corticosterone levels were determined in a radioimmunoassay. The results of the study revealed concentrations of ß-globulin and corticosterone levels were significantly higher in IF than UF groups in both lighting regimens. However, both parameters were higher in hens exposed to lighting regimen B than lightening regimen A. Gamma-globulin concentrations were significantly lower in IF than UF groups in both lighting regimens. Egg production was significantly lower in all groups than commercial standard. D. gallinae and intermittent lightening regimen had interaction effect on the corticosterone level in hens. Strong decreasing (negative) linear relationship between corticosterone levels and egg production (r = -0.911) was reported.