I had the opportunity to observe a auto-feeder representative teach an owner how to run the cleaning operations for an automatic calf feeder. What an education for me!
A recent research report, "Health of dairy calves when using automated feeders in the Midwestern United States", M. Jorgensen and Others, J. Dairy Sci. Vol 97, E-Suppl. 1, p18, abstract # 36, supplied information on the bacteria counts for milk samples obtained from the tube leading to the nipple.
The median (the halfway point between lowest and highest) values for the 38 sample farms were 2,550cfu/ml coliforms and 330,000cfu/ml standard plate count. So, are these numbers good? Or, are they bad?
The upper thresholds I use for milk being fed to calves are 500cfu/ml coliforms and 5,000cfu/ml standard plate count. So, in my opinion these are not good numbers.
I watched the company rep show the operator how to set up a "cycle-clean" operation. This means detaching the feeder tubes from the stalls and nipples. The tubes are transferred to a station on the machine that will allow the hot detergent wash solution to circulate through the entire system - a rinse cycle is included as well. It looks to me that this is an aggressive cleaning routine that is farm is planning to use twice a week. Some samples sent for bacteria culturing will confirm that is plan is working.
Thus, we conclude auto-feeders need to be cleaned and if one follows the manufacturer's directions they can be kept clean.