Ascaridia galli challenge model in laying hens

Abstract

Ascaridia galli is one of the most prevalent helminths in free-range laying hens. This study was conducted to establish a reliable infection model for A. galli in laying hens. Materials and methods : A total of 20 Lohmann brown hens of 19 weeks age were assigned to 4 treatment groups (n=5 per group). Hens of group 1 were orally inoculated with 1000 A. galli eggs stored at 26°C, group 2 with 1000 A. galli eggs stored at 4°C and transferred to 26°C prior to inoculation. Hens were infected 3 times over a week period. Hens of group 3 were orally inoculated with 500 A. galli eggs stored at 26°C, 6 times over 2 week period. Hens in group 4 were infected with adult A. galli via cloaca. Intestinal immature worms were counted from 2 hens from each group after slaughter at 2 weeks post infection (p.i).Excreta was collected and analysed for A. galli eggs at 8 and 14 weeks p.i.. Blood was collected to examine A. galli specific antibodies and intestinal A. galli worms were counted at 16 weeks p.i. results: Hens in group 3 had the highest A. galli worm counts (P<0.001) after slaughter at 16 weeks p.i. compared to other groups. Excreta A. galli egg counts were highest in group 1 and 3 (P=0.02). Serum antibodies among the 3 orally infected groups was similar, but were higher than in hens of group 4 (P<0.01). conclusion: Thus, The method either of inoculating hens orally with 500 A. galli eggs 6 times over 2 weeks period, or with 1000 A. galli eggs 3 times over a week period was the most reliable method tested.