Is Serum Total Protein a Useful Predictor of Clinical Johne's Disease in Dairy Cows that are ELISA-positive for Mycobacterium avium subsp paratuberculosis?

Abstract

ELISA tests are often used to identify cows subclinically infected with Mycobacterium avium subsp paratuberculosis (MAP). However, they lack diagnostic sensitivity and specificity and are not necessarily useful to predict if or when a subclinically infected cow might develop clinical signs of Johne's disease (CSJD). If producers could predict this, they might cull a cow sooner to avoid economic losses associated with CSJD. A study of one infected herd reported that cows with low serum total protein levels (STP<6. 7 g/dl) in the pre-calving period were at increased risk of culling due to CSJD in the subsequent lactation (Raizman et al, Prev Vet Med 80: 166, 2007). The objective of this study was to describe, for ELISA-positive cows, whether STP, serum albumin (SALB), ELISA SP ratio (ESPR), or level offecal shedding (FS) on ELISA test day are associated with subsequent risk for developing CSJD.