The results were as follows:

Bacterial Swab ResultsDisinfectantNumber of bacterial colonies per swabNone28.4Disinfectant13.2Disinfectant 219.6

Disinfectant 1 was able to reduce bacterial load of the pens compared to undisinfected pens. This indicates that to complete the washing process, the use of a disinfectant is beneficial.

There may be some variation due to choice of disinfecant, as I could not statistically show that hose pens sprayed with Disinfectant 2 had lower bacterial counts than undisinfected pens. Neither the use of hot water or a soap reduced the bacterial laod of the pen as measured by sampling the pens after the disinfection process.

Growth and EfficiencyWashing MethodDays to Market
25 kg to 110 kgNo Disinfectant98.14Disinfectant 195.40Disinfectant 295.11Soap Only95.59Soap and Disinfectant 192.96Soap and Disinfectant 292.66

The use of hot water had no effect on growth rate, but both disinfectants and the use of soap did. We are in the process of a second study to verify those results, but it is interesting to note that washing with a soap, while it did not appear to lower bacterial counts, it did improve the performance of the pigs. The only explanation I have is that when we swab pens we do not measure all the bacteria. Some bacteria would not be detected by swabs. Viruses or parasites would not be picked up either.

Soap acts like a degreaser, and loosens dirt and dissolves a waxy layer we call a biofilm that can coat pen floors and walls. The biofilm can protect bacteria and viruses from washing and disinfection. The biofilm can be hard to remove except with a soap, which can dissolve it.

We could not detect any difference in feed conversion or carcass quality due to washing type.

It appears that washing protocols can have a significant impact on productivity. Where possible, producers can evaluate their washing methods to see if they can be optimized.

Source: Atlantic Swine Research Partnership - Published by ThePigSite June 2003