DAIRY FARM MANAGEMENT PRACTICES AND CHARACTERISTICS OF HERDS POSITIVE FOR JOHNE'S DISEASE AND/OR BOVINE VIRAL DIARRHEA IN THE INTERMOUNTAIN WEST

摘要

The objective of the study was to record herd characteristics and management practices on dairy farms positive for either Johne's disease (JD) and/or bovine viral diarrhea (BVD) virus in bulk tank milk. Positive status for JD or BVD was defined by finding at least one positive test result (JD by PCR or ELISA, BVD by PCR) from five milk samples collected at 3-4 day intervals from all bulk tanks on 151 participating dairy farms. The farms were located in Utah and southern Idaho. There were 67 herds detected with JD and/or BVD in bulk milk, and 22 farms participated in a follow up visit project. The 22 farms were visited and evaluated using a questionnaire and standardized observations. An owner and usually other key personnel were interviewed and farms were observed.Twenty herds were JD positive only, one was BVD positive only, one was positive for JD and BVD. For all 22 herds, means and medians respectively were: number milking cows, 778, 420; 305d milk production, 20,052 lbs (9240 kg), 20,311 lbs (9221 kg); SCC inbulk milk, 175,545/ml, 178,000/ml. Holsteins were the main breed on 21 farms (95%), Jerseys the main breed on one farm (5%), but 15/22 farms (68%) had a mixture of Holsteins, Jerseys or other breeds. Fifteen farms (68%) milked in herringbone parlors, six (27%) milked in parallel parlors, and one (5%) milked in a rotary parlor. Number of milking units ranged from 6 to 160, with a mean of 28 units.