While milk testing for dairy cattle started in the late 1800's, DHI (Dairy Herd Improvement) associations designed to perform uniform efficient testing of milk and milk components were not formed until the early 1900's. Local milk testing associations in Vermont, which would later become Vermont DHIA, were among the first in the country. A more comprehensive history of DHIA can be found in the Journal of Dairy Science publication at http://jds.fass.org/cgi/reprint/64/6/1269.pdf.Other Historical References
USDA National Agricultural Library
The DHIA Supervisor's Manual (1956)
The National Cooperative Dairy Herd Improvement Program: A Handbook for Extension Workers (1963)
The National Cooperative Dairy Herd Improvement Program Handbook (1965)
University of Maryland
The National Cooperative Dairy Herd Improvement Program Handbook (1992)
