Zootecnica International - World Poultry Journal

Scott M. RUSSELL
Ph.D. Associate Professor
Department of Poultry Science
Poultry Science Building
University of Georgia
Athens, GA
U.S.A.

The United States Department of Agriculture - Food Safety and Inspection Service (USDA-FSIS) regulation requires that poultry slaughter facilities be evaluated for Salmonella on an intermittent basis. Typically, a USDA Inspector in Charge (IIC) will receive notification that he or she should begin testing and the following will occur:

1. One carcass per day will be selected, rinsed, and the rinse will be mailed to the USDA-FSIS laboratory and tested for the presence of Salmonella.
2. Carcasses will be selected and tested for approximately 51 processing days or until 51 carcasses have been evaluated. In some cases, carcass rinses must be discarded and more rinses are collected. For example, if carcass rinses were temperature abused or lost during shipment, they would not be tested.
3. Thirteen or more positives out of 51 samples (> 23.5 %) results in a failure.
4. Once the first failure (Set A) occurs, the plant is given 30 days to make corrections, and the testing series (51 samples) begins again.
5. After a second failure (Set B), the company must write an action plan detailing corrective actions that will be taken to prevent the problem from recurring.
6. Testing resumes 30 days after the second testing series has been completed.
7. Once the third failure (Set C) has occurred, inspection will be withdrawn, which effectively closes the processing plant (USDA, 1996).

Three failures by poultry plant results in layoffs, loss of reputation, and lost business. In addition, flocks must be processed by another plant that is owned by the same company or the birds must be sold to another processor.
These regulations have recently caused enormous problems within the poultry industry. Initial baseline studies by the USDA indicated that nationwide, raw broiler chicken carcasses were 20 % positive for Salmonella. Thus, the USDA set the maximum limit for Salmonella on chicken carcasses at 23%. By taking the average prevalence nationwide, and making it the new maximum level for prevalence, the USDA effectively made a rule in which almost 50 % of the processors in the country were producing carcasses that were out of specification for Salmonella prevalence. Since that time, researchers and poultry companies have been attempting to institute numerous intervention approaches to lower Salmonella prevalence on carcasses. These measures have had some impact. The effect of implementation of these measures was able to lower the national prevalence of Salmonella to approximately 9.5 %. However, since that time, the national prevalence has increased back to the levels observed during the baseline study. Likewise, the number of processing plants that are failing the Salmonella performance standard is increasing (Figure 1). Many of the factors that influence this increase are not taken into account by the Salmonella performance standard and are due to changes during the growout process. This regulation places all of the responsibility on the plant to reduce the level of Salmonella on finished raw carcasses. Thus, drastic interventions are sometimes required.

The following are real-world examples and represent data collected from various processors nationwide. Due to the confidential nature of this subject, none of the companies have been identified in the article.
Reducing Salmonella on finished carcasses requires a comprehensive, multi-hurdle approach. Many interventions are available during breeding, hatching and growout; however, these approaches will not be addressed in this article.
The purpose of this article is to provide suggestions regarding the proper tuning of a processing plant to meet the standard, regardless of the incoming load of Salmonella. No individual procedure or step is adequate to accomplish this task (i.e. there is no silver bullet). The USDA stated that "intervention strategies aimed at reducing fecal contamination and other sources of Salmonella on raw product should be effective against other pathogens" (USDA, 1996). This statement is misleading in that reducing fecal contamination has not been sufficient to reduce Salmonella prevalence. Reducing fecal contamination may be effective for reducing the number of Salmonella on each carcass; however, only one Salmonella cell is required on a carcass to produce a "positive" result. Thus, unless all Salmonella are eliminated, the carcass will still remain positive.
To begin the troubleshooting process, data must be collected. Carcass samples should be collected at the following locations to determine which interventions are working:

1. Post-bleedout
2. Post-scald
3. Pre-online reprocessing
4. Post-online reprocessing
5. Post-chill

Aerobic plate counts, E. coli counts, and Salmonella prevalence should be determined for carcasses at each of these locations over a period of time. For example, an appropriate sample size would be to collect 96 carcasses at each sampling point over a period of 12 days. This sample size is sufficient to determine variability between flocks and if the interventions are consistent over time.
The following graphs represent actual industrial data. For each of the graphs from the individual plants, the problems will be identified and solutions will be suggested.

In Scenario 1, the birds are coming into the plant highly contaminated. Scalding is having a minor impact, but not much. The online reprocessing system is doing all of the work and should not be changed; however, it cannot be solely relied upon to reduce Salmonella. The chiller is not pulling its weight.
The chiller should be the most effective intervention in the plant due to contact time. The recommendation would be as follows:

1. Use interventions during growout to lower the level of Salmonella coming into the plant
2. Balance the scalder
3. Balance the chiller

In Scenario 2, the birds are coming into the plant fairly contaminated. Scalding is having a major impact on Salmonella; however, the pickers are increasing the prevalence to higher than incoming levels. The online reprocessing system is not doing its job sufficiently. The chiller is the only intervention that is working well enough to allow the plant to remain in compliance.
The recommendation would be as follows:

1. Use interventions during growout to lower the level of Salmonella coming into the plant
2. Add a post-bleed brush system to remove any clumps of fecal material from the carcasses prior to scalding
3. Introduce a chemical (chlorine) into the sprayers within the pickers and introduce a post-pick spray
4. Change or optimize the online reprocessing chemicals used

In Scenario 3,the birds are coming into the plant at a controllable level. Scalding is havingno impact on Salmonella. The online reprocessing system is not doing itsjob sufficiently. The chiller is the only intervention that is working wellenough to allow the plant to remain in compliance. The chiller should not berelied upon solely to fix the problem.

The recommendationwould be as follows:

1. Balancethe scalders
2. Introducea chemical (chlorine) into the sprayers within the pickers and introduce apost-pick spray
3. Changeor optimize the online reprocessing chemicals used

In Scenario 4, the birds are coming into the plant at a controllable level. Scalding iscausing cross-contamination of carcasses with Salmonella. The onlinereprocessing system is not doing its job sufficiently. The chiller is the onlyintervention that is working well enough to allow the plant to remain incompliance. The chiller should not be relied upon solely to fix the problem.

The recommendationwould be as follows:

1. Balancethe scalders and make sure the temperature is correct
2. Adda post-bleed brush system to remove any clumps of fecal material from thecarcasses prior to scalding
3. Thisplant is likely running the first two scalder tanks at 110 to 123ºF to increaseyield. This is making the scalder a huge Salmonella inoculation chamber.
4. Introducea chemical (chlorine) into the sprayers within the pickers and introduce apost-pick spray
5. Changeor optimize the online reprocessing chemicals used

In Scenario 5,the birds are coming into the plant at a controllable level. Scalding iscausing cross-contamination of carcasses with Salmonella. The onlinereprocessing system is not doing its job sufficiently. The chiller is notpulling its weight and the carcasses are over the legal limit with regard to Salmonellaprevalence.

The recommendationwould be as follows:

1. Adda post-bleed brush system to remove any clumps of fecal material from thecarcasses prior to scalding
2. Balancethe scalders and make sure the temperature is correct
3. Thisplant is likely running the first two scalder tanks at 110 to 123ºF to increaseyield. This is making the scalder a huge Salmonella inoculation chamber.
4. Introducea chemical (chlorine) into the sprayers within the pickers and introduce apost-pick spray
5. Changeor optimize the online reprocessing chemicals used
6. Balancethe chiller

In Scenario 6, the incoming birds are highly contaminated, but the scalder is balanced, thepickers are not contributing to the problem, the online reprocessing system isworking well, and the chiller is balanced appropriately. This scenario isachievable. A handful of plants around the country are able to operate asdepicted in Scenario 6.

More detailedsuggestions as to how to improve the interventions are provided below; however,a much more thorough discussion is given in an extension bulletin at thefollowing web address (http://pubs.caes.uga.edu/caespubs/pubcd/B1222.htm):

1. Scaldersshould be balanced by:
   a. Ensuring properwater flow (counter-current)
   b. Keep the scaldersat the proper temperatures (above 123ºF)
   c. Maintainsufficient fresh water input at the bird exit (minimum of 1/4 gallon/bird)
   d. Eliminate "deadspots" where feathers and foam buildup, especially at the bird exit
   e. Consider usingsome of the scalder disinfectants that will be available for use very soon
2. Thechiller should be balanced by:
   a. Making sure the pHis around 6.5 and no greater than 7.5
   b. Adding chlorine ata level of 50 ppm to the bird exit
   c. Adding fresh waterto the bird exit at a level of at least 1/2 gallon/carcass
   d. Ensuring theproper flow direction (counter-current)
   e. Making sure thechiller is large enough to accommodate the size of carcasses being processed(carcasses should NOT be exposed and above the water line)
   f. Use chlorine todisinfect the redwater
   g. Redirect theredwater reentry pipes away from the carcass exit (foam buildup protects Salmonellaand the carcasses pass through it as they exit)

Please keep in mindthat each plant is different. When a problem occurs, each plant must beevaluated and a unique plan should be developed to correct the problem. Thegood news is that problems may be identified and corrected provided enoughinformation is available. Often, when working on these problems, theinformation is not available and must be collected after the problem occursand, in some cases, after the plant has been shut down. Thus, a catch 22occurs. The plant management asks the question, how can we demonstrate that wehave fixed the Salmonella problem when we cannot run the plant?

The examplespresented are but a few of the possibilities that may be seen in the industry.Sometimes the problem is very simple, at other times, multiple fixes arerequired. On some occasions, the plant cannot be balanced and efforts must bemade in the field. This occurs when the plant is using very old equipment, isunable to install new equipment due to cost or space limitations, or may notimplement certain chemicals due to poor ventilation.

In general, it ismuch more expensive to implement field interventions than to correct theproblems in the plant.

Every plant shouldstrive to achieve a pattern as is presented in Scenario 6. This level ofperformance is achievable.

Unfortunately, somecompanies choose to wait till the last Salmonella set (Set C) beforethey seek help. At this point, enormous amounts of money are required to fixthe problem. Moreover, once the USDA-FSIS begins to see Salmonella setfailures, the plant is placed under intense scrutiny. It is much less expensiveand more effective to be proactive and control the problem.

 

From Proceedings of the "Midwest Poultry Federation Convention", St.Paul, Minnesota, U.S.A.