The present study evaluated the repellent activity and the improvements in egg production and mortality rate on laying hens infested with poultry red mites (PRM) administered with a mixture of Korean traditional herbal methanolic extracts (CHE, Foeniculum vulgare : Sophora flavescens : Cinnamomum cassia : Glycyrrhiza glabra = 1:1:1:1, w/w/w/w). PRM numbers per laying hens in CHE-0.5 administered with CHE 0.5 kg/ton feed were significantly decreased compared to those in Non-CHE (control) during overall experimental periods (1st week post-treatment, p<0.05; 2nd week post-treatment, p<0.01; 3rd-4th week post-treatment, p<0.001). In CHE-1.0 administered with CHE 1.0 kg/ton feed, PRM numbers were significantly decreased compared to those in Non-CHE during the whole experimental periods (1st week post-treatment, p<0.01; 2nd-4th week post-treatment, p<0.001). After administration of CHE for 4 weeks, egg production and mortality rate in CHE-0.5 and CHE-1.0 were significantly improved compared to those in Non-CHE (p<0.05). In addition, hematological and blood biochemical parameters in all CHE-treated groups were insignificantly different compared to those in Non-CHE. This study showed that CHE (0.5 and 1.0 kg/ton feed) had a repellent activity on PRM in laying hens and effects on the improvement in egg production and mortality rate of laying hen. CHE could be an effective and safe candidate for the control of PRM and the improvement in egg production and mortality rate of laying hens.

Abstract
INTRODUCTION
MATERIALS AND METHODS
    A combined herbal extract (CHE)
    Animals and experimental diets
    PRM populations
    Egg production rate, mortality rate and egg weight
    Hematological and biochemical analysis
    Statistical analysis
RESULTS
    Changes in PRM numbers per bird
    Egg production, mortality rate and egg weight
    Blood cell counts and serological values
DISCUSSION
REFERENCES

• Won-Suk Chae(Schools of Life-Chemistry, Daejin University)
• Chang-Yeul Yoo(Department of Computer Software Science, Gyeongnam Provincial Namhae College)
• Eun-Kee Park(Department of Medical Humanities and Social Medicine, College of Medicine, Kosin University)
• Suk Kim(Institute of Animal Medicine, College of Veterinary Medicine, Gyeongsang National University)
• Hu-Jang Lee(Institute of Animal Medicine, College of Veterinary Medicine, Gyeongsang National University) Corresponding Author