Putting Science Back Into Disinfectants

Pork producers need to reevaluate whether the proper cleaning agents are being used for hog barns, trailers and even boots. Pork producers may think they

Pork producers need to reevaluate whether the proper cleaning agents are being used for hog barns, trailers and even boots.

Pork producers may think they are using the correct disinfectants in their sanitation programs, but if they are arbitrarily using one product over time, it's a good idea to revisit what product is being used and what for, says Alex Ramirez, DVM, adjunct assistant professor in Swine Production Medicine at Iowa State University (ISU).

If you prefer to use a broad-spectrum, economical product, then household bleach is as cheap as it gets. However, there are certainly limits to its use because of its strength, and health concerns when working with concentrated products (Table 1).

For products to be effective against specific viral diseases, such as porcine reproductive and respiratory syndrome (PRRS) and circovirus, producers are fortunate to have a broad array of disinfectants that have been shown to be effective in laboratory tests and field trials, says Ramirez.

Remember the point of disinfectants is to try to target the specific pathogens that are impacting your operation, and break the cycle of disease, rather than just relying on a general product to cure all problems.

“Step back and prioritize the diseases of concern because they may change over time, therefore, you may need to change disinfectants over time,” Ramirez stresses.

However, don't just decide on a whim that it's time to give a different disinfectant a try. “You wouldn't make changes in your vaccine and antibiotic programs just for the heck of it. So think about what you are trying to target and what your objectives are when it comes to selecting disinfectants,” he notes.

In the same vein, use caution when rotating disinfectants, says Ramirez. The theory is that resistance to some products can build up over time.

“But there should be some good reason for changing disinfectants: cost, not getting good control or, for example, instead of having lots of problems with PRRS, you now are having more problems with salmonella. Those are good reasons to change. But just to change every three months to avoid resistance — there is no science to document that,” he stresses.

The Role of Disinfectants

Disinfectants are chemicals used to control, prevent or destroy a variety of microbes. They are designed for application to objects, as opposed to antiseptics and germicides, which are intended for skin application.

For a list of several types of products, their levels of effectiveness and precautions for their use, refer to Characteristics of Selected Disinfectants (Table 1 on page 16).

Producers should also avoid the “more is better” mentality, Ramirez says. If the label directions call for a solution of 1 oz. of disinfectant/gal. of water, then upping that proportion to 5 oz. of disinfectant/gal. of water may seem like it would increase efficacy, but it usually adds little benefit at five times the cost. And it's also a violation of federal law for disinfectants as regulated by the Environmental Protection Agency.

Disinfectants are a critical, final step in the cleaning process. But the ISU veterinarian makes it clear that they are not the total solution when it comes to sanitation on a hog farm.

Cleaning is much more important in the sanitation process than disinfectants, he says, because washing with detergents will bring the level of pathogens down to a low level. Then disinfectants comprise that final cleaning step that protects the environment from contamination, according to Ramirez.

Research on boot baths by Sandy Amass, DVM, now director of the National Biosecurity Resource Center at Purdue University, provides a case in point. In studies conducted several years ago, Amass showed that just standing in a disinfected boot bath for five minutes did little to decrease the amount of contamination on the bottom of her boots.

However, studies showed that once those boots were scrubbed and hosed off, allowing the disinfectant to contact the boot's bottom surface, cleanliness was achieved. Those two practices have virtually replaced boot baths in hog barns, Ramirez says.

Buy boots with wider ridges on the bottom to facilitate this cleaning process, he suggests.

The biosecurity center also provides assistance with selection of the proper disinfectant by logging onto www.biosecuritycenter.org/disinfect.php.

The Power of Water

Power washing is commonly viewed as the least desirable job on the hog farm, but it may provide the highest return when done right, Ramirez says.

The best thing to do is to walk through a building after washing and look for manure or organic material in corners and under feeders. “If you can find manure, there is probably contamination, and that will tell you that the workers didn't do a good job,” he explains.

Just as water is essential for life, proper drying is vital to complete the cleaning process.

It's difficult to provide the recommended 24 hours between cleaning and filling a room. But try to schedule pig flows to provide the maximum downtime, Ramirez says, to give disinfectants time to make contact with surfaces and drying to be completed.

Drying Differences

Properly drying transport trailers can also be a difficult challenge in trying to break the cycle of disease, says Ramirez. Many integrators who can't wait for trailers to dry naturally have gone to trailer-baking systems.

Most might think PRRS, a tough disease that mutates frequently, might be the toughest to get rid of in a trailer. That's not quite true, says Ramirez. PRRS virus is inactivated at 160-180° F, similar to foot-and-mouth disease.

PRRS is an enveloped virus, that serves to protect the virus in the environment, but that envelope is in fact fragile and fairly susceptible to heat and chemical disinfectants. “The challenge is in making sure that we have thoroughly cleaned the trailer,” he says.

In contrast, circovirus is one of the non-enveloped viruses that are very hardy. Circovirus doesn't mutate nearly as frequently as PRRS in the pig, but it persists much longer in the environment. Research indicates that to inactivate circovirus, temperatures must reach 248° F, he says.

Trailer baking stations provide two essential elements: plenty of heat and they dry the trailers, completely ridding them of moisture that sustains all forms of life including viral and bacterial pathogens, says Ramirez.

Herds that are PRRS-positive, for example, may think that cleaning and disinfecting hog barns is a waste of time and money.

But reducing that pathogen load in the environment is critical to providing pigs with the best opportunity to fight off diseases, thus delaying the onset of clinical signs until pigs are older and better able to withstand disease challenges, he says.

Missing the Boat

All-in, all-out production and the cleaning that goes with it are key elements in preserving pig health. But so is maintaining cleaning within production groups, Ramirez suggests.

Producers are “missing the boat” when they allow manure buildup to persist, especially in farrowing, giving piglets access to possible disease agents passed on by the sow.

Perform regular scraping to minimize contamination, and give staff the chance to better evaluate sow health.

Farms that do a better job of consistently keeping barns clean inside also do a better overall job of keeping building exteriors in order, enhancing biosecurity, Ramirez concludes.

View both tables in a printable Word Document