Washing Does Work
During two recent farm visits I observed the calves being fed from a mobile unit with a feeding tank on the back, pump and a nozzle controlled by the driver. Drive up, squeeze nozzle, feed calf, drive on to next calf, repeat.
In both cases I obtained samples of raw milk, milk directly from the pasteurizer, milk coming out of feeding nozzle.
Overall bacteria culture results?
1. Relatively low bacteria counts for raw milk.
2. Virtually no bacteria in samples coming from the discharge hose from the HTST pasteurizers.
3. Significant bacteria counts in the milk coming out of the feeding nozzle.
Compare these counts for one farm:
Raw - 3,100
Pasteurized - 500
Nozzle - 20,700 including 5,700 coliforms.
Hmmmm. Looks like post-pasteurization contamination.
The other farm went from no growth on pasteurized sample to the nozzle results of TNTC (TNTC gram positives, 7,000 E. coli, 4,000 Klebsiella) [TNTC = too numerous to count]
More post-pasteurization contamination.
As soon as they received the bacteria culture results from the our lab the second farm changed their wash routine - rather than washing the hose and nozzle used to feed calves by just draining the tank wash water out through it they started fixing the hose and nozzle so they circulate wash water as the tank washes.
They did this for three days twice a day. Then they collected more samples. Milk going into the tank virtually no bacteria. Milk coming out the nozzle - the lowest count was 620 cfu/ml and the highest count was 1,602cfu/ml of the four samples cultured. This may be compared to the TNTC sample from the same equipment before the revised washing protocol.
Washing does work, especially if all of the equipment gets washed.
Just as an aside, the calf care person at this second dairy noted that the frequency of scours problems among young calves has dropped significantly since the new wash protocol was put into place.