Barn Wash/Disinfection Trials

By Dr. Dan Hurnik, Industry Chair for Swine Research - Washing of pens or barns has become a routine part of pig production. The reasons are numerous, but the main one is that washing removes bacteria, viruses and parasites left behind from the previous batch of pigs.
calendar icon 21 June 2003
clock icon 6 minute read

Take me to the ARSP website. Most diseases are dose dependant; this means the higher the dose a pig is exposed to the sicker they'll get. Washing the pens reduces the number of disease causing organisms and so the animals grow better and are healthier.

The use of a soap is often recommended because it will help remove the greasy film of organic matter that sticks firmly to the pen floor or wall. This biofilm can shelter bacteria and viruses from removal and disinfection.

Disinfectants are used to kill whatever bacteria or viruses remain after washing. Generally disinfection has been deemed essential, but it is not effective without a thorough wash first. Organic matter such as manure or bedding needs to be removed before a disinfectant will be effective.

Disinfectants are among the most hazardous chemicals in barns. They can be toxic and corrosive. People need to apply them only at the dilutions recommended and need to be protected with proper clothing. Some disinfectants are more toxic than others; always read the label and ask your veterinarian for advice on safety and effectiveness.

With washing and disinfection a regular part of pig production, I wanted to examine various washing methods to determine if there are any efficiencies to be had.

Materials and Methods:

We washed 40 pens (over two fills) with a combination of the following:

  • Hot water versus cold water
  • Presoaking versus no presoaking
  • Soap or no soap before wash
The soap used was a commercially available barn degreaser, which is biodegradable and licensed for use in livestock barns. As outcomes, we measured how long it took to wash each pen, we swabbed the pens to determine how clean they were, and we measured how well the pigs grew.


Some interesting results arose. In this newsletter I will just present the wash time data, and will discuss the disinfection and pig growth in the next newsletter.

The results were as follows:

Wash Procedure Time To Wash Pen (minutes) Difference (minutes) Time Savings (%)
Cold Water
No Soap
No Presoak
68.03 0 0
Cold Water
59.80 -8.23 12.1
Cold Water
41.39 -26.64 39.1
Cold Water
36.38 -31.65 46.52
Hot Water
No Soap
No Presoak
52.61 -15.42 22.6
Hot Water
46.24 -21.79 32.0
Hot Water
41.88 -26.15 38.43
Hot Water
36.81 -31.22 45.9


Presoaking pens with water to loosen manure can cut washing time almost in half. Overall, the use of hot water speeds up washing time about 22%, except in the case of presoaking where the use of hot water didn't decrease wash time when compared with cold water.

The use of soap speeds up washing about 8 minutes per pen (about 12%) Another observation worth noting is that while hot water is more comfortable to apply, it can create a fog that sometimes makes it harder to see. The washing time saved is not just about labour; it also reduces wear and tear on the pressure washer, and reduces water usage and subsequent manure volume as well.

Significant labour is used on modern pig barns to wash and disinfect pens and rooms between groups of pigs. The results did not surprise me, except for the magnitude of time savings to be had by presoaking the pens prior to washing.

The other question I wanted to answer was whether there was a benefit in the performance of the pigs by the various washing methods. I did not compare washing to no washing, as in the industry we have adopted regular washing as an essential part of pig production. It is a required element in the Canadian Quality Assurance program, so the option to not wash doesn't really exist.

I really did not know what to expect from the results, and when they came in they were puzzling at first.

We measured how clean the pens were based on swabbing the pens and counting the number of bacteria remained in pens. We also measured the growth of the pigs and the feed conversion, and we looked at the carcass quality of the pigs after processing.

The results were as follows:

Bacterial Swab Results
Disinfectant Number of bacterial colonies per swab
None 28.4
Disinfectant 13.2
Disinfectant 2 19.6

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 Efficiency
Washing Method Days to Market
25 kg to 110 kg
No Disinfectant 98.14
Disinfectant 1 95.40
Disinfectant 2 95.11
Soap Only 95.59
Soap and Disinfectant 1 92.96
Soap and Disinfectant 2 92.66

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
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