Table 1.

Literature-reported blood components associated with sheep RFI

Biomarker	Biomarker classification	Sample type	Correlation	Reference
Thyroxine, adrenocorticotropic hormone, cortisol	Hormone	Serum	Positive	Richardson and Herd, 2004; Knott et al., 2010; Zhang et al., 2017
Albumin, creatinine, total plasma protein, glucose	Metabolites	Serum	Positive	Rincon-Delgado et al., 2011; Paula et al., 2013
Red blood cells, white blood cells	Hematological and biochemical parameters	Serum	Positive	Rincon-Delgado et al., 2011
Mean corpuscular volume, mean corpuscular hemoglobin, eosinophils, monocyte	Hematological and biochemical parameters	Serum	Negative	Rincon-Delgado et al., 2011; Paula et al., 2013

A limited number of research have investigated significant blood components associated with sheep RFI. None of these studies implemented metabolomics and no rigorous biomarker analysis was conducted to verify if these compounds could serve as proxies of RFI.