A demonstration project of interdisciplinary dairy herd extension advising funded by industry and users. 2. Impact on herd performance.

The objectives of this 24-herd, demonstration project of extension advising were to measure the impact of integrated problem solving on measures of DHI performance for 2 yr during and 2 yr after the project. During project advising, increases in rolling herd average milk and fat yields and 3.5% FCM were similar for project and state herds. When rolling herd average for milk yield for state herds was adjusted for two USDA milk reduction programs, milk yield of project herds was estimated to have increased 434 lb more per cow than that of DHI state herds. Compared with state DHI trends, project producers significantly improved in percentage of low SCC, days open, and age at first calving. Two years postproject, DHI milk yield declined for project and state herds, probably because of drought. Demonstration herds did not outperform state DHI herd average in milk yield or in other efficiency parameters during the 2-yr postproject. The extension advising in the demonstration project had the most positive impact on management of low ranking herds. Only low ranking herds had an advantage in rate of improvement, compared with high ranking herds, in rolling herd average for milk yield during and after the project and in SCC and days open during the project. Gains by managers of herds ranking low and in the middle in DHI parameters were generally lost or declining postproject.