Understanding compost bedded pack barns: Interactions among environmental factors, bedding characteristics, and udder health

• Effect of compost bedded pack moisture on herd hygiene score.
• Effect of temperature humidity index on compost bedded pack temperature.
• Effect of compost bedded pack temperature and moisture on bedding bacteria.
• Effect of ambient temperature and compost bedded pack factors on udder health.

The objective of this study was to describe relationships among compost bedded pack barn (CBP) measurements (moisture, internal temperature, nutrient content, and bedding bacterial counts), ambient weather conditions, and udder health. Data was collected every 2-weeks (n=25 visits) from 8 Kentucky dairy farms with CBP from May 2013 to May 2014. A single observer scored 50 cows per farm for hygiene and collected compost internal temperature, moisture, and compost samples from 9 evenly distributed areas in each barn. Weighted average somatic cell count (SCC), high SCC prevalence (HSP), and reported clinical mastitis incidence (RCMI) were collected from herd records and milking personnel.Compost internal temperature increased with increasing maximum barn temperature (BT). Compost moisture content decreased with increasing BT. Herd hygiene score decreased with increasing BT and increased with increasing compost moisture content. Herd SCC and HSP both increased with increasing BT but were unaffected by compost measurements. As compost internal temperature increased, staphylococci, streptococci, and bacilli species growth in the pack area decreased and coliform species growth increased. Low CBP moisture and high CBP temperature reduced bacteria levels. Cow hygiene and udder health indicators had a stronger relationship with BT than with CBP internal temperature and moisture.