Abstract
Subclinical mastitis (SCM) is a very common disease of dairy cows. Currently, somatic cell count (SCC) is used for SCM diagnoses. There are no prognostic tests to detect which cows may develop SCM during the dry-off period. Therefore, the objectives of this study were to identify metabolic alterations in the serum of pre-SCM cows during the dry-off period, at −8 and −4 weeks before calving, through a targeted mass spectrometry (MS) assay. Fifteen cows, free of any disease, and 10 cows affected only by SCM postpartum served as controls (CON) and the SCM group, respectively. Results showed 59 and 47 metabolites that differentiated (p ≤ 0.05) CON and pre-SCM cows at –8 and −4 weeks prior to the expected date of parturition, respectively. Regression analysis indicated that a panel of four serum metabolites (AUC = 0.92, p < 0.001) at −8 weeks and another four metabolites (AUC = 0.92, p < 0.01) at −4 weeks prior to parturition might serve as predictive biomarkers for SCM. Early identification of susceptible cows can enable development of better preventive measurements ahead of disease occurrence.
Highlights
Subclinical mastitis (SCM) is the most common intramammary infection (IMI) of dairy cows
Just 10 cows were diagnosed as affected by subclinical mastitis only (SCM, n = 10; 424,710 Somatic Cell Count (SCC)/mL), free of other diseases, and 15 cows that were ascertained to be completely free of periparturient diseases (CON, n = 15; 27,450 SCC/mL)
Preliminary results of this study showed that there were major changes in the concentrations of several lipid species, amino acids (AAs), and organic acids (OAs) metabolites in pre-SCM cows versus CON ones at both −8 and −4 weeks prepartum
Summary
Subclinical mastitis (SCM) is the most common intramammary infection (IMI) of dairy cows. It poses a significant challenge for cow’s health and profitability of dairy farms [1,2]. During the dry-off period, cows have been found to be in a state of low-grade chronic inflammation at −8 and −4 weeks prepartum [6,7]. The potential reason for the chronic low-grade inflammatory state might be translocation of pathogenic bacteria, presence of bacterial endotoxins, or transport of proinflammatory cytokines from the sub-clinically infected udder to the systemic circulation [8]. The need to monitor cows during the dry-off period to identify cows at risk of SCM is critical in developing preventative measures and better farm management strategies
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