Reducing salmonella risk in table egg production

Rodent feces can contain infectious amounts of Salmonella. Mouse feces, common in feed troughs, may amplify Salmonella disease in poultry. Rodents also carry disease to nearby and distant houses and farms.

Keep rodents out

• Remove all rodent covers inside and outside the poultry house. This may include:

  • Shrubs or tall grass

  • Garbage or construction debris

  • Broken equipment

  • Burrows under the foundation

• Install a rodent barrier along the exterior of the poultry house.

• Seal all entrance holes inside and outside the building.

  • Fix and close siding sheet seams.

  • Make sure doors and door frames fit tightly.

• Seal holes and cement cracks in manure pits.

• Make sure rodents don’t reside in reused filler flats, which can move to and from farms during egg delivery.

• Secure feed bins and sheds at night. Clean up dead birds and broken eggs daily.

Bait rodents

Caution: All baits are harmful to rodents, chickens, animals and people.

Preparing to bait

• Remove all feed from feeders right after house depopulation, so rodents promptly go to the bait.

• Remove all other food sources such as spilled feed, broken eggs and dead birds.

• Check the outside of buildings often for rodent holes.

Selecting bait

Warfarin, diphacinone and pival are rat poisons that work by thinning the blood. To be effective, rats must receive these poisons in multiple doses over several days. Thus, poison works best if you use it routinely, every two weeks.     

Newer blood thinners contain brodifacoum and bromadiolone. These may cause death three to five days after a single feeding. You can use single-dose rat poison at any time, especially right after house depopulation.

Make sure to stock enough rat poison to meet the farm's long-term needs.

Placing bait

• Place baits to avoid contaminating feed and eggs or coming in contact with poultry and humans.

  • Don’t place bait loosely on the ground in high-traffic areas. People may carry it on their shoes and contaminate sensitive areas.

• Save bait by only baiting holes with rodent activity.

1. Fill all rodent holes with dirt or paper.

2. Check for open holes later.

3. Only bait the open holes.

• Follow the manufacturer’s directions when placing the bait.

• Control attic rodents by installing an attic access hatch and baiting with a high-wax, single-dose poison at least once yearly.

• After controlling rodents, inspect and keep up permanent bait sites every two weeks. Record the location and numbers of trapped mice and maintain these records.

Using multiple control methods reduces the likelihood that insects will adapt to a single method.

For example

• Keep manure well ventilated and dry.
• Prevent water leaks and remove wet areas.
• If possible, use biological control methods (fly parasites and predators).
• Use different types of insecticides.

Applying insecticide

1. Clean and disinfect the poultry house floor.
2. Once the floor is dry, apply an approved insecticide to the floor, support poles, and walls.
3. Always follow the manufacturer’s safety precautions.

You can use synergized pyrethrins (pyrethrin plus piperonyl butoxide) in automatic spray systems inside poultry houses. These quickly knockdown flying insects, have short residual times and have low toxicity in mammals. Don’t apply these insecticides more than twice weekly, especially if you use a spray system.

• Avoid spilling feed outside the buildings and clean up any spills right away.

• Buildings should keep out wild birds and prevent them from sitting under eaves or on blinds.

• Keep pets out of pullet and layer houses.

Clean the facilities as soon as you remove any birds that tested positive for Salmonella. Cleaning will prevent replacements from contamination.

Good cleaning programs need to:

• Be put in place across the entire farm

• Have proper equipment

• Have professional training

Cleaning conventional facilities presents a significant challenge for the following reasons.

• Facility size and complexity

• Wooden construction materials are harder to disinfect than smooth metal surfaces

• Plastic and fibrous egg handling surfaces are harder to disinfect than smooth metal surfaces

These problems reduce the effectiveness of cleaning plans. In the past, many used formaldehyde to help disinfect porous surfaces. Although effective against Salmonella, its use is constrained by human safety concerns, limited product availability, and regulatory policies. Other options may help disinfect porous surfaces.

• Other fumigants

• Heat-enhanced disinfectants

• High-pressure sprays or disinfectant foams

• Sealants to reduce the rough surface of wood

• Clean fans and other air inlets from the outside.

• Moving from top to bottom, clean up the dust inside the building. For example, remove dust from the ceiling, beams, walls, cages etc.

• Promptly open feeder lines and remove all feed including feed inside troughs.

• Open egg conveyance equipment at the front of the building and remove all dust and egg debris. Remove broken and soiled parts that you can’t clean.

• Do your best to remove manure from dropping boards.

• Remove all litter and manure from floor or cage houses, including augers and pit ends.

  • Be aware of National Institute for Occupational Safety and Health alerts on manure pit hazards.

  • If you can, fill trailers with manure inside the house and cover it before hauling to a disposal or composting site. Manure should not be spread near poultry facilities.

• Remove egg belts and sweep away all debris above and below the belt.

• Remove all debris and items not needed from the entire building.

• Turn off power to electrical equipment prior to cleaning. Use compressed air or brushes to clean non-removable motors, switches, etc. Take extra care to keep sprays out of electric motors. Use duct tape to cover the motor slots before wet cleaning and disinfection. Remove the tape after wet cleaning and disinfecting.

Soaking and washing

1. Soften dirt in heavily soiled areas. Use a low-pressure (200 to 300 pounds per square inch) sprayer, which delivers 10 to 30 gallons per minute. Hot water and cleaners can help loosen debris and films that salmonella can grow in.

2. While washing, start at the back and work toward the front. Spray the ceiling first, then the walls and lastly the floor. Thoroughly clean everything.

3. Use sprayer attachments and nozzles that allow you to wash hard-to-reach places.

• Aim for 750 to 2000 pounds per square inch.

• High pressure requires extra care and safety clothing. Pressure sprayers can cut human skin like a knife. Always follow the manufacturer's instructions for use.

• Be sure to wash under the troughs and hidden surfaces of chains and augers.

• Clean the egg elevator completely. Check that each angle (from under the pit and from behind rollers) is clean. Remove all traces of egg.

• Wash storage and egg rooms, egg coolers, hallways, break, wash and restrooms.

• Clean any other areas by hand if you haven’t cleaned them already.

Rinsing

A final rinse reduces residues of cleaning chemicals. Make sure to remove puddles right away to prevent bacteria from growing in them.

Repairs

Make all repairs after rinsing including:

• Filling floor cracks

• Repairing door frames

• Replacing damaged panels

• Repairing manure, egg handling and other equipment

Dirt floors

Add 3 to 6 inches of clean soil to houses with dirt floor pits to decrease risk of disease in new flocks. We don’t know the value of this for preventing salmonella.

Have a third-party inspect your facility after wet cleaning and repairs. This may be done by an outside authority or by an in-house, unbiased employee in quality control.

Start disinfecting within 24 hours of rinsing. Disinfectants are only effective on clean surfaces.

Heat enhancement

All disinfectants work best at temperatures over 65 F. Temperatures for chlorine- and iodine-based disinfectants shouldn’t exceed 110 F.

Dangerous mixtures

Always follow the manufacturer’s instructions for human and flock safety. Avoid adding chemicals to disinfectants without the manufacturer’s approval. Adding chemicals can dangerously reduce product efficacy.

Disinfectants

• Apply 1 gallon of diluted disinfectant to approximately 100-150 square feet of surface area.

  • To determine how much disinfectant you need, find the total surface area of the floor, ceiling and walls. Add 30 percent to this area to allow for cage surfaces.

• Follow manufacturer instructions to apply disinfectants.

  • Use a pressure sprayer (500-1000 psi) to force disinfectants into wood pores and cracks. Move from back to front and from top to bottom.

• Dirt floors are almost impossible to fully disinfect. Apply one gallon of diluted disinfectant per 10 square feet to dirt floors.

• Disinfect egg handling equipment following the equipment and disinfectant manufacturer recommendations.

  • Disinfecting egg belts with steam, vats of water at pasteurization temperatures, or soaking could help, but their efficacy and potential adverse effects on the belt are unknown.

• Clean feed bins, boots, augers, hoppers and carts. Sanitize water lines.

  • Improper use of sanitizing agents can plug lines or damage metal and non-metallic parts of watering systems.

  • Check with your farm’s water handling equipment manufacturer before using any specific chlorine or other treatments of your wells or water lines.

• Promptly dry the building. You can use bullet space heaters to speed drying in cold or damp climates.

• Test your facility for Salmonella following disinfection. Make sure results are negative before placing chicks or ready-to-lay hens in your facility.

Formaldehyde and formalin

WARNING: Formaldehyde and formalin are dangerous chemicals. Always contact state/federal (EPA, OSHA, FDA) authorities and licensed professionals before considering use. You will need gas masks, protective clothing and rescue plans when using these.

In the past, producers used formaldehyde (formalin) as a disinfectant for Salmonella. Producers also used formaldehyde fumigation (gas) as a final crack- and pore-cleaning step when relative humidity was at least 70 percent, and temperature was at least 70°F.

You can sample numerous surfaces, including:

• Ceilings, walls and floors

• Fan housings and blades

• Cages

• Waterers and feed troughs

• Manure scrapers

• Egg belts, rollers and sponges

How to collect samples

Use 33- or 44-inch multi-layered, lightly moistened gauze pads. Gauze pads allow you to forcefully wipe large (22-foot) areas. A damp pad allows particles to adhere more effectively.

Only use cotton-tipped swabs to sample hard-to-reach areas.

Always wear sterile disposable gloves when sampling. Promptly refrigerate samples at 35 to 38 F.

Rodent trapping is a primary sampling strategy.

Drag swabs are gauze pads connected to a cord that are drawn over droppings and litter. They produce results that reflect the Salmonella gut-carrier or organ-infection status of chickens.

How to collect samples

Draw two gauze pads connected to a cord over fresh droppings along the full length of each row.

• Use one two-pad drag swab set per row in caged pullet or layer houses.

• Drag two or three two-pad drag swab sets over the litter surface if you keep your flocks on litter. Draw the swabs over the litter at the pen ends, sides and center.

  • Make sure each two-pad drag has contact with the litter for at least five to six minutes.

_^aA laboratory manual detailing sampling and culture procedures and a magazine update on culture media improvements have recently been published.

_^bAn additional test for salmonella in one-day-old hatchlings is described in the mentioned laboratory manual (Chapter 1, page 5).

_^cAt any age, bacteriological examination of culls, fresh dead, and trapped mice especially, are used to enhance detection efficiency.

_^aA laboratory manual detailing sampling and culture procedures and a magazine update on culture media improvements have recently been published.

_^bUse of cull eggs and/or blood (serum) samples are currently being evaluated as additional or alternative monitoring tools.

_^cAt any age, bacteriological examination of culls, fresh dead, and trapped mice especially, are used to enhance detection efficiency.

_^dMore frequent monitoring during lay has also been suggested to increase the likelihood of prompt detection of contamination.

Protect eggshell strength

Salmonella can get into weak shells more easily. Avoid weak shells by:

• Having properly formulated feed at all ages.

  • For example, supplement with adequate calcium and vitamin D3.

• Vaccinating for infectious bronchitis and Newcastle disease, which weakens the shell.

Gather eggs frequently

Eggs exposed to temperatures of 80 to 90 F promote bacterial growth and increase Salmonella risk.

Properly wash eggs

In-line washing systems

Wash the eggs and cool them to 45°F or lower. Use only potable water with a maximum iron content of 2 parts per million and a minimum wash-water temperature of 90°F.

Nest run systems

Cool the eggs to 60°F immediately before washing. This will avoid cracks during washing. If the egg and wash water temperatures differ by 50 F or more, you may need to pre-warm the eggs before washing. Make sure the wash and rinse solutions are 10 to 15 F warmer than the eggs.

Use sanitizers following the manufacturer’s recommendations.

After washing, cool the eggs to 45°F or lower if sweating can be controlled.

Provide good storage and transport temperatures

Eggs should remain at 45 F during storage and transport.

Control inventory

Rotate the product at all levels of distribution, warehousing, sale and home or institutional use. This inventory control decreases the likelihood of Salmonella growth in the product.

Label food properly

State on egg carton labels that eggs are perishable (will spoil) and require the same care, including cooking, as other animal-source foods. More informed consumers benefit both producers and their customers. Store eggs in their original cartons in the main section of the refrigerator, not on the door shelf, where they can reach 60°F.

Don’t reuse fiber flats and egg cartons. Reusing these can save you money, but they can also spread disease. Plastic flats are better suited to reuse, but you must wash and disinfect them after each use.

Salmonella can contaminate both the egg shell surface and the inside of the egg. Salmonella contaminates the inside of an egg either before the egg fully forms or by entering the shell.

Proper egg washing and sanitizing can rid egg shell surfaces of salmonella but not salmonella inside the egg. Cool temperatures play a key role in preventing further salmonella growth inside eggs.

Egg white contains products that help kill or stop the growth of bacteria. These natural products become less effective as the egg whites age. Cool temperatures help slow egg white aging and thus, help it control bacterial growth.

Cold temperatures alone can also prevent or reduce the growth of salmonella organisms. Research shows that Salmonella enteritidis put into eggs, didn’t grow at 40 F, but did grow at 50 F. Thus, by reducing egg temperature to 45 F or lower, you can reduce the risk of salmonella growth.

• Obtain feed from mills that follow the guidelines:

  • Recommended Salmonella Control for Processors of Livestock and Poultry Feeds, published in September, 1988 by the American Feed Industry Association, 1501 Wilson Blvd., Suite 1100, Arlington, VA 22209.

• Use animal protein ingredients from rendering plants taking part in the Animal Protein Producers Industry (APPI) Salmonella Reduction Education Program.

• Keep feed ingredients and finished feed at all stages of manufacture and storage dry.

• Keep rodents out of feed.

• Keep feed dry.

• Seek advice from your nutritionist and veterinarian before using anti-salmonella feed additives.

  • These differ in effectiveness and mode of action and may be subject to Food and Drug Administration (FDA) regulatory control.

• Start your own bank of feed samples.

  • Feed banks and testing promote quality control.

  • Store samples in a clean, dry place at room temperature.

Competitive exclusion (CE) is a natural mechanism by which gut bacteria protect the bird from pathogens. You can buy and feed CE to your flocks.  

Prompt post-hatch colonization of CE gut bacteria, in a clean environment, may help reduce the risk of Salmonella growth in the gut of normally Salmonella-prone young fowl. CE cultures appear to accelerate the growth of potential protective gut bacteria.

Probiotics aren’t quite the same as CE cultures.

Routinely chlorinating poultry drinking water to at least 1 to 1.5 parts per million of free chlorine level reduces the spread of salmonella.