Start with sick and dying calves. Jump to the most attractive explanation: "It must be a bug."
 
The "bug" in this case is some exotic highly pathogenic bacteria or virus that has invaded the dairy and is the sole cause the sick and dying calves.
 
Thus, when the dairy reaches out for professional assistance to solve the sick and dying calf problem the dairy already knows how to find the solution. That is, "Find the BUG."
 
At our most recent visit to a dairy with this situation we had difficulty walking across the bedding pack where calves are born. Why? Less than 50 square feet per cow stocking rate. And, none of us would want to kneel down on the bedding in this pen - ugh.
 
Blood agar cultures of colostrum being fed to the calves uniformly resulted in plates with too many colonies to count - well over 1/4 million per ml - with very heavy growth on the MacConkey plates showing heavy coliform contamination.
 
No interest in participating in blood sampling of youngest calves to check on immunity levels. 
 
Necropsy data from calves from a university laboratory failed to find "THE BUG."
 
What is the next step?
 
One alternative is to keep looking for "the bug." Send more dead calves to the lab. Find other professionals to help in the search for "the bug" since the ones involved so far were not competent enough to find "the bug."
 
Another alternative is to step back, assemble a "team," and assess the calf management program from top to bottom. Identify opportunities to reduce pathogen exposure and increase immune defenses. 
 
If you are interested, two web resources that provide checklists for these are:
 
and 
 
As a regular reader of this blog I do hope you are not among the "bug hunters."