Heavy infestations of the blood-sucking gastrointestinal nematodes, Haemonchus contortus can cause severe anaemia in sheep and leakage of blood into the faeces, leading to morbidity and mortality. Early and accurate diagnosis of infections is critical for timely treatment of sheep, minimizing production and sheep welfare impacts. In pursuit of a quick and easy measure of H. contortus infections, we investigated the use of portable visible near infrared spectrometers for detecting the presence of haemoglobin in sheep faeces as an indicator of H. contortus infection. Calibration models built within the 400–600 nm region by partial least square regression resulted in acceptable prediction accuracies (r 2 p > 0.70 and root mean squared error of prediction <2.64 µg Hb mg−1 faeces) for haemoglobin quantification using two spectrometers. The prediction results from support vector machine regression further improved the prediction of haemoglobin in moist sheep faeces (r 2 p > 0.87 and root mean squared error of prediction <2.00 µg haemoglobin mg−1 faeces). Based on a threshold for anthelmintic treatment of 3 µg Hb mg−1 faeces, both the partial least square and support vector machine models showed high sensitivity (89%) and high specificity (>77%). The specificity of the prediction model for detecting haemoglobin in sheep faeces may be improved by adding more variations in faecal composition into the calibration model. Our success in detecting haemoglobin in sheep faeces, following minimal sample preparation, suggests that with further development, vis–near infrared spectroscopy can provide a sensitive and convenient method for on-farm diagnosis of H. contortus infections.

中文翻译：

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可见-近红外光谱用于检测绵羊粪便中的血液

消化道吸血线虫的严重侵染会导致绵羊严重贫血和血液渗漏到粪便中，导致发病和死亡。感染的早期和准确诊断对于及时治疗绵羊、最大限度地减少生产和绵羊福利影响至关重要。为了快速简便地测量扭曲变形杆菌感染，我们研究了使用便携式可见近红外光谱仪检测绵羊粪便中是否存在血红蛋白作为扭曲变形杆菌感染的指标。通过偏最小二乘回归在 400–600 nm 区域内建立的校准模型产生了可接受的预测精度（r 2 p > 0.70 和预测的均方根误差 <2.64 µg Hb mg-1 粪便），用于使用两个光谱仪进行血红蛋白定量。支持向量机回归的预测结果进一步改进了湿羊粪便中血红蛋白的预测（r 2 p > 0.87 和预测的均方根误差 <2.00 µg 血红蛋白 mg−1 粪便）。基于对 3 µg Hb mg-1 粪便进行驱虫治疗的阈值，偏最小二乘和支持向量机模型均显示出高灵敏度 (89%) 和高特异性 (>77%)。通过将粪便成分的更多变化添加到校准模型中，可以提高用于检测绵羊粪便中血红蛋白的预测模型的特异性。我们在最少的样品制备后成功检测了绵羊粪便中的血红蛋白，这表明随着进一步的发展，可见近红外光谱可以提供一种灵敏且方便的方法来诊断扭曲变形虫感染的农场。