Figure 2.

Example of a chain of citations in the Johne's disease literature evaluating the claim that immediate cow-calf separation reduces Johne's disease prevalence. Newborn calf care (Goodger et al., 1996) represents an aggregate of the following management practices: (1) whether colostrum was harvested from a clean udder (free of manure), (2) whether the bottles used to store colostrum were clean, (3) whether colostrum was pooled, and (4) whether calves were permitted extended contact with the dam. MAP = Mycobacterium avium ssp. paratuberculosis.