Relationship between facility type and bulk tank milk bacteriology, udder health, udder hygiene, and milk production on Vermont organic dairy farms

ABSTRACT: The primary objective of this cross-sectional observational study was to determine whether bulk tank milk quality, udder health, udder hygiene, and milk production outcomes were associated with facility type on organic dairies. A secondary objective was to identify other management-related risk factors associated with bulk tank milk quality, udder health, udder hygiene, and milk production on organic dairy herds in Vermont. We aimed to enroll 40 farms, to compare herds using the 2 most common systems (freestalls, tiestalls) for housing organic dairy cattle in the state with those using a bedded pack during the nongrazing season (typically November–May). Two general styles of bedded packs were observed: cultivated bedded packs and untilled deep-bedded packs. Due to the limited number of herds using bedded packs to house lactating dairy cattle in Vermont, we combined untilled and cultivated bedded packs to describe udder hygiene, milk quality, and udder health on these loose-housing systems deeply bedded with organic material. The study was completed on 21 farms (5 bedded packs, 6 freestalls, 10 tiestalls) before interruption due to the COVID-19 pandemic. Data captured from DHIA records from the test closest to the date of the farm visit included average SCS, standardized 150-d milk (pounds), percentage of cows with current high SCS (SCS ≥4.0), percentage of cows with newly elevated SCS (previous SCS