Use of the egg hatch assay on sheep faecal samples for the detection of benzimidazole resistant nematodes
Hunt, K.R.; Taylor, M.A.
Veterinary Record 125(7): 153-154
1989
ISSN/ISBN: 0042-4900 PMID: 2800272 Document Number: 327580
Anaerobic conditions developed within three hours when 10 g samples of faeces were mixed with 90 ml of water in 100 ml screw-top plastic bottles and incubated at 27 degrees C. Faecal samples stored in this simple anaerobic system at 27 degrees C provided undeveloped nematode eggs for detecting benzimidazole resistance in egg hatch assays for up to 7 days after collection of samples. After 7 days the egg mortality exceeded 5% of the population. When benzimidazole resistant and susceptible strains of Ostertagia circumcincta and Haemonchus contortus were used in the in vitro egg hatch assay, the anaerobic storage of eggs for 7 days had no significant effect on the ED50 values when compared with the values for eggs from fresh samples. Variation in ED50 values and resistance factors with storage did occur but remained within normal limits.