Visible-near infrared spectroscopy for detection of blood in sheep faeces

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Kho, Elise; Fernandes, Jill; Kotze, Andrew; Lord, Maggy; Fox, Glen; Beasley, Anne; Moore, Stephen; James, Peter


2020-09-10


Journal Article


Journal of Near Infrared Spectroscopy


28


255-266


Heavy infestations of the gastrointestinal nematode, Haemonchus contortus, can cause severe blood loss in in sheep, leading to morbidity and mortality due to the blood-sucking habit of this parasite. The current on-farm method for evaluation of anaemia resulting from H. contortus infections is highly dependent on operator expertise; therefore it is not commonly used across sheep meat and wool production industries. In pursuit of a quick and easy measure of infection, we investigated the use of visible-near infrared (vis-NIR) spectroscopy for detecting the presence of blood in sheep faeces as an early indicator of H. contortus infection. We assessed haemoglobin (Hb) concentrations, as a measure of blood, in sheep faeces using portable vis-NIR spectrometers (QualitySpec Trek and Felix F-750). Calibration models built within the 400 – 600 nm region, with pre-processed data by partial least square (PLS) regression resulted in high prediction accuracies (R2Pred 0.70 and RMSEP 2.64 µg Hb/mg faeces) for Hb quantification using both NIR spectrometers. The application of support vector machine (SVM) regression further improved the prediction of Hb in moist sheep faeces (R2Pred 0.87 and RMSEP 2.00 µg Hb/mg faeces). Based on a decision threshold of 3 µg Hb/mg faeces for anthelmintic treatment, predictions using the SVM model had sensitivity = 89%, specificity = 80%, positive predictive value = 79% and negative predictive value = 90%. Predictions using the vis-NIR spectrometer had similar accuracies compared to a conventional faecal occult blood test (vis-NIR R2 = 0.91; conventional test R2 = 0.88) when tested on laboratory-prepared samples. The success in detecting Hb in sheep faeces indicates the potential of NIR spectroscopy as a rapid on-farm diagnostic method for blood in sheep faeces, which could have a range of veterinary applications beyond early diagnosis of H. contortus infections.


NIR Publications


Veterinary Parasitology


EP196684


Journal article - Refereed


English


Kho, Elise; Fernandes, Jill; Kotze, Andrew; Lord, Maggy; Fox, Glen; Beasley, Anne; Moore, Stephen; James, Peter. Visible-near infrared spectroscopy for detection of blood in sheep faeces. Journal of Near Infrared Spectroscopy. 2020; 28:255-266. http://hdl.handle.net/102.100.100/375830?index=1



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