Efforts intensify to reduce Salmonella enteritidis infection in laying hens
The FDA Egg Safety Rule has resulted in efforts to comply with reasonable and proactive procedures to prevent SE
The implementation of the FDA Egg Safety Rule in July 2010 followed by the Wright County SE outbreak of August 2010 has led to significant concern and efforts to reduce SE infection by U.S. egg producers. There is a considerable financial impact arising from a flock testing positive by sampling of manure and if subsequently confirmed as SE positive by assaying egg pools.
A positive manure test of pullet housing at 14 to 16 weeks of age or of laying units at 40 to 45 weeks of age will result in a significant loss to operations. A positive environmental or manure swab requires expensive testing of four successive 1,000 egg pools representing an expenditure of from $2000 to $10,000 depending on the lab fees.
The egg testing process is complicated by the fact that producers must either hold eggs or divert to breaking from the time of collection until test results are received. This is due to the potential for a recall should the eggs test SE positive. Prior to the approval of more rapid detection tests such as PCR or immune-based test kits, a producer had to wait for up to 10 days for individual BAM-based assays before obtaining a negative result which would allow packing and distribution of retained eggs. In practice the use of rapid detection tests following enrichment has reduced storage time to 3 working days plus time to transport to a laboratory.
An egg-positive confirmation is even more serious due to the cost of diverting production to breaking for at least eight weeks if four consecutive tests are negative or the remaining life of the flock. This is illustrated by the egg price quotation on February 10, 2011, of $1.17/dozen, Urner Barry Large grade Midwest eggs and $0.46/ dozen, or 5 cents off the UB breaker price of $0.51/dozen. The calculated loss of income from diversion over eight weeks required for four successive negative egg pool tests amounted to $1.24 per hen or $124,000 per 100,000 birds.
Producers who were previously not vaccinating have now adopted live Salmonella typhimurium vaccination programs. Operations previously using only an all-live ST program are now adding an SE bacterin. Some farms considered to be at risk have intensified their programs by introducing a second SE bacterin. Extra-label boosting of immunity with live ST vaccine during lay or just prior to molt is also practiced to maintain both tissue and humoral immunity.
Rodent control programs have been upgraded on most farms as mice are proven carriers of SE. Greater attention is now devoted to fly control in accordance with the FDA “Final Rule.”
The fear of feed-related SE infections has led to many producers requiring microbiologic assay of high-risk ingredients prior to purchase to avoid possible infection of flocks with SE. In some cases, ingredient suppliers are treating their products with formaldehyde or organic acid-based commercial additives to reduce or eliminate the risk of SE contamination. Many producers have in fact eliminated animal-source ingredients from both pullet and hen diets.
There has been greater use of compounds to promote intestinal health in an effort to improve protection against SE. Probiotics in the form of Lactobacillus and Bacillus cultures to supplement diets are available. Prebiotic additives usually derived from yeast fermentation are in demand. Research has demonstrated a beneficial effect on intestinal microflora which inhibits intestinal colonization with SE. A few products have beneficial effects on the immune cells of the intestine which aid in reducing infection rates. Some producers are using a combination of fermentation metabolites, probiotics, and prebiotics as insurance. In addition, some feed additives have been shown to significantly improve performance providing a very cost effective extra dimension of protection to ongoing SE prevention programs of biosecurity, rodent control and vaccination.
Producers using contractors operating farm packers that store eggs for more than 36 hours have invested heavily for increased refrigeration capacity in order to comply with the 45 F directive of the FDA “Final Rule.” More diligent attention to maintaining the designated temperature and recording data, especially during hot weather was evident during the past summer.
Producers are closely following the reports from FDA on the results of inspections of the high-risk producers to learn what criteria and standards are applied by the FDA during inspections. Examples of items that are cited for failure as reported in FDA 483 Reports are:
- Failure to have a site-specific SE Prevention Plan (SEPP)
- Failure to record that chicks were obtained from NPIP-tested sources, such as vaccination and cleaning
- Failure to record times that certain activities were performed
- Failure to provide records of rodent and fly control
- Failure to document personal biosecurity measures as described in the SE Prevention Plan
- Pest Control
- Failure to control rodents
- Failure to follow the frequency of monitoring as outlined in the company SEPP
- Failure to prevent stray animals from entering layer houses
- Failure to remove debris or vegetation from around houses
- Failure to provide fly monitoring records
- Egg Storage
- Failure to maintain eggs in storage at a temperature of 45F or below
- Failure to monitor pullets at 14 to 16 weeks of age
- Failure to monitor hens at 45 weeks of age
- Failure to maintain practices to prevent cross-contamination when workers move among houses
Basically, to pass inspection, it is required to have a practical, valid, written program in place and to implement the SEPP with supporting records and documentation.
The bottom line
The FDA Egg Safety Rule has resulted in intensified efforts to comply with reasonable and proactive procedures to prevent SE. These involve upgraded biosecurity, compliance with NPIP “SE Clean” directives, effective rodent and fly control, vaccination, supplementary probiotic and prebiotic supplements and refrigeration of eggs after collection through to delivery to stores or distribution centers.
Adapted from a presentation at the 2011 Midwest Poultry Federation Convention.