Giardia duodenalis is a ubiquitous protozoan parasite

My cows have lost weight this winter and the yearlings in lots have not gained nearly enough.

This promped a fecal sample.  

All samples came back with this parasite in them.   Very little is known about the problem and some vets didn't realize it could exist in cattle.

I found one study about it on the web.  Heres the link to it. 

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2759911/?tool=pubmed
All I know about it is what I read on the site.

A call has been made to CSU's Vet Med program and am waiting a call back. 

Has anybody had this problem?    What were your problems with it? What did you do about it?  Thanks.