Observations of benzimidazole efficacies against Ascaridia dissimilis, Ascaridia galli, and Heterakis gallinarum in naturally infected poultry

SUMMARY Two studies were conducted to provide current efficacy evaluation for benzimidazoles used in poultry. In the first study, naturally infected laying hens from an organic, free-range facility were treated with fenbendazole as an oral drench at the rate of 5.0 mg·kg −1 of BW. Based on treatment group, geometric means for all stages combined, fenbendazole was 85.5 and 89.5% effective for the removal of Ascaridia galli and Heterakis gallinarum populations, respectively. In the second study, naturally infected turkeys from a commercial grower were treated with albendazole as an oral suspension at the rate of 10 mg·kg −1 of BW, treated with fenbendazole as an oral suspension at the rate of 5 mg·kg −1 of BW, treated with fenbendazole for 6 d with feed medicated at the concentration of 16 ppm, or left as control. Based on treatment group geometric means for all stages combined, efficacies for A. dissimilis were 0, 71.4, and 83.3% for albendazole drench, fenbendazole drench, and fenbendazole-medicated feed, respectively.