Abstract #86

# 86
Factors associated with aerobic plate count, coliform count, and log reduction of bacteria in automated calf feeders.
Alyssa M. Dietrich*1, Whitney A. Knauer2, Sandra A. Godden2, Christina S. Petersson-Wolfe1, Robert E. James1, 1Virginia Tech, Blacksburg, VA, 2University of Minnesota, St. Paul, MN.

As automated calf feeders become more widely adopted, there is a need for research on sanitation management. The objective was to identify factors associated with bacteria counts and log reduction (LR) as a result of circuit cleaning (CC) in milk/replacer samples collected from automated calf feeders (Förster Technik, Engen, Germany). It was hypothesized that increased cleaning is associated with low bacteria counts and increased LR. Six VA and 4 MN dairy farms (14 feeders) were visited weekly for 7 mo. Samples of milk/replacer were collected aseptically from each feeder, iced, and frozen at −5°C. For a 4-wk period, VA farms were instructed to collect and freeze samples immediately before and after CC. Samples were thawed and plated on Petrifilms to find log10 aerobic plate count (APC) and log10 coliform count (CCP). From a model of state, farm(state), LSM ± SE APC was 3.84 ± 0.26 and 5.02 ± 0.21 log10 cfu/mL (P < 0.01), and CCP was 0.62 ± 0.47 and 2.89 ± 0.39 log10 cfu/mL (P < 0.01) for MN and VA. The LSM by farm ranged from 3.30 to 5.51 log10 cfu/mL APC and 0.07 to 3.82 log10 cfu/mL CCP. The LR of APC (LRAPC) and CCP (LRCCP) after CC was 0.78 ± 0.82 and 0.67 ± 1.17 log10 cfu/mL (mean ± SD). By regression, each log10 increase in pre-CC APC and CCP increased LRAPC and LRCCP by 0.45 log10 cfu/mL (P < 0.01). Farms with higher pre-CC APC and CCP cfu/mL performed more CC/wk and used more mL detergent/L water (P < 0.05). More mixer cleanings (MCHE)/d lowered pre-CC APC cfu/mL (P < 0.05), whereas use of silicon hoses increased pre-CC CCP cfu/mL (P = 0.04), and use of bleach decreased pre-CC CCP cfu/mL (P < 0.01). By stepwise regression with farm in the model, more days since last MCHE increased LRCCP (P < 0.01) within farm. Number of calves, milk L/d, and feeder visit frequency were not associated with LR of bacteria within farm. LR was more dramatic at high pre-CC bacteria, which was reduced by more MCHE/d and use of bleach.

Key Words: bacterial count, automated calf feeders