Detection of Haemonchus contortus nematode eggs in sheep faeces using near and mid-infrared spectroscopy

Abstract

This paper reports the use of near infrared and mid-infrared spectroscopy to detect the presence and quantity of eggs of the gastrointestinal nematode Haemonchus contortus in sheep faeces. Haemonchus contortus eggs were quantified in dried, finely ground sheep faeces and in moist, coarsely ground faeces using near infrared and mid-infrared bench top spectrometers and a portable near infrared spectrometer. When Haemonchus contortus eggs were presented without faecal medium, it was found that the wavelength region of 1880–2100 nm was most important for detection. Broad classes of chemical properties found in the near infrared region were identified for dried Haemonchus contortus eggs using a mid-infrared spectrometer. However, when Haemonchus contortus eggs were mixed into the complex matrix of sheep faeces, the development of a robust calibration model for egg detection proved to be challenging (R2 < 0.47). The reliability of this method, if used for the detection of Haemonchus contortus eggs in the field, may be further limited by variations in egg species, faecal moisture content, faecal composition and particle size. Nevertheless, this is the first report identifying near infrared bands for Haemonchus contortus eggs and provides valuable information for future studies towards a spectroscopy-based method for detection of gastrointestinal nematodes.