THE USE OF DISINFECTANTS IN THE SWINE INDUSTRY

Mark G. Ladd
College of Veterinary Medicine
North Carolina State University
Raleigh, NC 27606

Introduction

Many hog operations experience "disease build up" in facilities that have been in use for more than one group of hogs. Also, disease prevention is a constant battle a producer faces everyday. In order to break the trend of increasing prevalence of disease in older facilities and preserve desired levels of biosecurity, proper cleaning and use of disinfectants are crucial.

Definitions

Disinfectant: A chemical agent applied to inanimate objects which inactivates or destroys microorganisms. Some viral particles and spores are resistant to certain disinfectants.

Sanitizer: A chemical agent that reduces the bacterial, fungal, or viral population without killing the microorganism when applied to inanimate objects.

Detergent: A chemical agent that contains both cleansers and solvents. Detergents are added to water in order to reduce surface tension and to increase penetrating ability of water. This allows more organic matter (dirt) to be removed from surfaces.

Cleaning, Crucial for Success

Dirt, dust, manure, old feed, or any other organic matter in a hog house offers an excellent environment that protects microorganisms from disinfectants. First, disinfectants are limited in their ability to penetrate surfaces. Organic matter also inactivates some disinfectants. Therefore, it is crucial to remove all organic matter possible to get maximum benefits. Cleaning can be done with a shovel and brush followed be high velocity stream of water (200-1000 psi) or a steam generator. Detergents improve the ability to remove dirt and manure stuck to surfaces.

Tips to help improve cleaning/disinfecting of hog facilities

  1. Remove all portable equipment for separate cleaning.
  2. Remove all bedding or litter.
  3. Remove all loose dirt, manure and feed be scraping, brushing and sweeping.
  4. Next, use low pressure, high volume hosing or high pressure, low volume washing. Soak for 1-2 hours prior to washing.
  5. Clean the ceiling first, followed by the walls and then the floors.
  6. All surfaces must be cleaned and completely treated with the disinfectant solution.
  7. Apply disinfectant with a low pressure washer or garden hose applicator.
  8. Rinse if a corrosive chemical is used.
  9. Allow room/facilities to dry before animals are placed.
  10. Rinse and dry feeders before reusing.

Characteristics of an Ideal Disinfectant

  1. Inexpensive.
  2. Nonirritating and nontoxic to man and animals.
  3. No residue in meat.
  4. Noncorrosive and nonstaining to equipment and surfaces.
  5. Broad spectrum effectiveness against various infectious agents.
  6. Residual activity.
  7. Reasonable odor.
  8. Readily soluble in hard water.
  9. Availability.
  10. Capability to penetrate, preferably with a detergent action.
  11. Stable when diluted.
  12. Unaffected by environmental factors: organic matter, dirt, dust, soaps or detergents, pH, temperature, and relative humidity.

Factors Affecting the Efficacy of Disinfectants

Temperature: Higher temperatures enhance the antimicrobial activity for some of the disinfectants. On the other hand, chlorine and iodine are not active at temperatures above 110 F.

pH: The pH level of the surfaces and substances affect the efficacy of the disinfectant used. Quaternary ammonium compounds are more active at a high pH. Chlorine, iodophors, and phenols are more effective at a low pH.

Organic Matter: Organic Matter includes materials such as blood, body parts, dirt, dust, manure, and old feed. These substances protect microorganisms from some of the disinfectants. Iodophors and chlorine compounds are not effective when organic matter is present. Coal/tar based disinfectants, synthetic phenols, and cresylic acids are more effective in disinfecting surfaces covered with organic matter.

Compatibility with Detergents: Detergents that contain surfactants should rinse quite easily and not leave a film on surfaces. Surfactants are classified into two types: anionic and nonionic. A residue left on surfaces may inhibit the action of a disinfectant. For example, quaternary ammonium compounds are not as effective when anionic surfactants are remaining sa are phenolic disinfectants less active in the presence of nonionic surfactants.

Concentration: To qualify as a disinfectant, the FDA requires that a compound completely kill all microbial agents for which it is labelled within 10 minutes of application on nonporous surfaces. A 2-fold concentration increase is required for effective use on porous surfaces.

Types of Disinfectants

Saponated Solution of Cresol: These disinfectants contain soap and are more effective in hot solutions. They are effective on surfaces with minimal organic matter present and are acceptable to use on premises and vehicles. A strong odor persists after using.

Synthetic Phenols: There is very little odor associated with their use. They have a wide range of antimicrobial activity are reasonably active of surfaces with organic matter.

Iodines/Iodophors: Tinctures of iodine are solutions of 2% or 7% iodine in alcohol and are used as an antiseptic for minor surgical procedures. These compounds do stain surfaces as well as being corrosive and irritating. Iodophors, tamed iodine compounds, are nonstaining and nonirritating. They are commonly used to disinfect equipment and clean surfaces. Iodophors used with other disinfectants provide some residual activity but organic matter does interfere with their activity.

Chlorine Compounds: These compounds have very rapid action against most microorganisms. The presence of organic matter and sunlight rapidly reduces disinfecting properties.

Quaternary Ammonium Compounds (QAC): Quaternary Ammonium compounds are commonly used for disinfecting meat-packing and food-handling equipment. They are not effective against viruses and fungi. Organic matter and detergents also decrease antimicrobial activity.

Water Sanitation

Water sanitizers are used to control slime molds and bacterial contamination of drinking water. Some examples are listed below:

1) Chlorine: Chlorine is effective at 3-10 ppm. Sodium hypochlorite (bleach) is effective and inexpensive. Activity depends on pH, temperature, concentration, and exposure time.

2) Iodophors: Iodophors are more effective the chlorine but require more contact time. Effective levels are at 12.5-25 ppm.

3) Quaternary ammonium compounds: Quaternary ammonium compounds are not effective in the presence of organic matter and anionic surfactants. Also, they are not recommended to be used in hard water. Effective levels are at 200 ppm.

Take-Home Message

It is obvious to see the advantages of proper cleaning and use of disinfectants on hog farms in preventing "disease build up" and maintaining biosecurity. The time and energy needed are costly. However, proper use can possibly lead to higher production and overall improvement of herd health. It is extremely important to follow all instructions printed on the labels for safe and effective use. Your local veterinarian and agricultural extension agent are excellent sources to answer questions. For more information, Pork Industry Handbook article #80 and the February issue of Pork 93 Annual Guide to Health and Nutrition are excellent sources. The final page includes a table comparing various disinfectants.

Table 1. Characteristics of Some Common Disinfectants

.
Chlorine
Iodine
Quaternary Ammonium
Phenol
Cresol
Irritating
+
+/-
-
+
+
Staining
+
+/-
-
-
+
Residual
-
+/-
+
slight
+
Corrosive
+
+/-
-
slight
+
Active in Organic Matter
-
-
+
+
+
Volatile
+
+/-
+
-
-
Expense
low
mod
mod
mod
high

Table 2. Spectrum, Uses and Brand Names

.
Chlorine
Iodine
Quaternary Ammonium
Phenol
Cresol
Spectrum of Activity G+
+
+
+
+
+
Spectrum of Activity G-
+
+
slight
+
+
TB
slight
slignt
-
slight
slight
Spores
slight
slight
-
-
-
Fungi
+
+
slight
slight
slight
Viruses
slight
slight
slight
slight
slight
Uses
clean equip.
clean equip.
clean equip.
equip. premis, foot-baths
equip. premis, foot-baths
Brand Names
Chlorox
Beta-dine
Zephiran
Germex
Environ
Lysol

Note: The above information is recommended by Becker et al.