I read this interesting mail here, where in the authors have mentioned an NGO exporting Cow Dung and Cow Urine to USA.
I spoke to a family friend, who is now retired (from a CSIR lab as a senior scientist) and volunteers ~ 8 hours a day with a Gau Shala (गौ शाला) or Cow Shelter near Jodhpur.
He is vey keen to figure out who is buying this and how to go about it, since they have ~ 5, 000 cows - most of which are at the end of their life.
गौ सेवा is uplifting for the society and country. Hindu kingdoms had "गौ ब्राह्मण प्रतिपालक" as a guiding philosophy. (Standard disclaimer - Brahman signifies Guru / learned man - not an indicator of which family you were born in).
If American uses / buyers are documented, it would be useful to a number of GauShaalas.
Readers may kindly send any information by means of comments.