How Tyson Foods and Cargill control Salmonella in poultry live production

Veterinarians from Tyson Foods and Cargill MeatSolutions presented interventions that have proven effective in theircompanies’ preharvest Salmonella controlprograms.

Okeefe T Headshot
Courtesy Dr. Charles Hofacre
Courtesy Dr. Charles Hofacre

Salmonella  control strategies for ready-to-cook poultry products are fundamentally different in the U.S. and Europe. The European approach has been to attempt to eradicate Salmonella at the farm level and not to use any chemical interventions in the processing plant. Dr. Scott Gustin, head of domestic veterinary services for poultry, Tyson Foods, said that the U.S. approach has been to reduce Salmonella numbers on the live-side to low levels, particularly what he characterized as effective colonizing Salmonellas, and then to further reduce Salmonella levels in processing.

Speaking at the Poultry Federation's Salmonella Summit, he questioned whether the European approach of concrete floors in growing houses and total farm clean-outs after each flock would work in the U.S. He said the current tools being used by Tyson allow the grow-out farms to provide the plants with birds which have low levels of Salmonella, and bird performance has been improved by some of the measures undertaken to lower Salmonella levels.



"We get a lot of improvement in bird performance as a result of some of the live side interventions," Gustin said.



Salmonella control has spillover health benefits



The experience of at least one turkey integrator parallels what Tyson has experienced. Dr. Brian Wooming, veterinarian, Cargill Meat Solutions, said, "In many cases, the things that we do to control Salmonella are very good for controlling other organisms as well. It is important to realize that these interventions had positive impacts on some of the other [health] issues we were dealing with."



Some preharvest Salmonella control measures may help with disease control, but they don't lower Campylobacter numbers, according to Gustin. Because of this, he said that plant interventions, most of which work to lower both Salmonella and Campylobacter numbers, will still be required, even if Salmonella were eradicated on the farm.



Both Cargill and Tyson operate multiple complexes in the central, mid-Atlantic and southeastern regions of the US. Wooming and Gustin each pointed out that not all of their complexes employ the same preharvest Salmonella control interventions. Sampling for Salmonella throughout each complex's operations, breeder farms, hatcheries, feed mills, and growing houses, helps to determine which interventions should be employed.



Salmonella control in breeder operations



Gustin said that broiler primary breeders consistently supply breeding stock that has low to nonexistent levels of Salmonella. "We have to step it up as integrators to prevent and manage infection on breeder side," he said.



Wooming said that Cargill had traditionally hatched out its breeder stock at a facility that also hatched poults for meat bird farms. He said that Cargill is transitioning to a hatchery that is dedicated to hatching breeders to make sure that breeder stock stays Salmonella-free through hatch.



One of the real challenges of Salmonella control for breeders has to do with the design and age of most breeder houses. Gustin said that the average Tyson breeder house is around 25 years old. Dirt floors, nest boxes and exposed wood on house sidewalls all make cleaning and disinfection of the typical broiler or turkey breeder house difficult. Both Wooming and Gustin said that the industry needs to rise to this challenge.



"Primary breeders went to a lot of trouble to give the industry Salmonella-free product," Gustin said. "Producers need to make sure that their birds are placed in grow-out environments that help preserve that status as much as possible."



Attention to breeder house cleanliness, sanitation



Wooming said that all the litter must be removed from breeder houses after each flock, even when it means hand digging litter out of divots in the floor.



"We had to raise the level of expectation of what clean was at all of the farms," he said. "It took a lot of time and effort to get cleanout to the level we wanted to be at."



After cleaning and wash down, formaldehyde is used to disinfect all the breeder houses, Wooming reported. Downtime of three to four weeks is built into the schedule to make sure there is enough time to do everything properly.



Pest control has benefits, but requires planning



Rodents and insects reduce the efficacy of your downtime and carry-over numbers of "bad Salmonellas," according to Gustin.



"Your best bang for the buck on the breeder side is rodent control in the layer house," he said.



Rodent control needs to start when the birds leave the house but is more critical in the layer houses than pullet barns, he added.



A robust plan is needed for farms with existing rodent-control issues, he advised. The use of video cameras can help document rodent activity, especially where farm personnel need convincing that a problem exists.



Gustin offered the following advice for rodent control:


  • Don't use the same rodent bait all the time.


  • Rodent baits should be rotated by compound and palatability.


  • Monitor to make sure rodent control is working.



Pest control includes mowing, fencing, pesticides



Keeping the vegetation cut short around the poultry houses and plugging holes in house walls are important steps for controlling rodents. Electrified fences have been installed around Cargill poultry houses to keep varmints away. The company has contracted with an outside rodent control company to ensure uniformity throughout its breeder operations.



Darkling beetles and other insects can carry Salmonella from one flock to the next. A control plan for pre-placement and touch-up pesticide applications is needed, according to Gustin. Cycle length and application timing should be considered. Plus, when rotating baits make sure that active ingredients are rotated, not just brands.



Breeder vaccination programs



Cargill had a problem with Salmonella Heidelberg in one of its complexes, according to Wooming. Breeders in that complex are now vaccinated with a killed autogenous Salmonella Heidelberg vaccine. It is administered before the hens start laying eggs.



"The first year's data would imply that the killed autogenous Salmonella Heidelberg vaccine is more helpful for that specific serotype than was initially assumed," he said. "It is not the silver bullet, but it appears to be helpful."



Choose well when it comes to Salmonella strains



The purpose of a breeder vaccination program is to prevent infection with "bad serotypes" or "effective colonizers," according to Gustin. He said Tyson is "heavy" on killed vaccination programs, but is currently evaluating live Salmonella vaccines. A regional approach to bacterin programs is needed, he said. Pick good colonizing serotypes for autogenous products, he advised. For example, pick Salmonella Heidelberg or Salmonella Typhimurium over Salmonella Schwarzengrund in the B group and Salmonella Infantis over Salmonella Tennessee in the C group.



"Don't leave a spot open for effective colonizers, and make sure to include at least one strain of Salmonella in the B group," he said. "We also elect to use one shot of commercial killed SE products in our breeders, we want to protect the bird against true vertical transmission. Salmonella vaccination can work, but you still need to do everything else."



Wooming said that environmental sampling in the layer house is a critical part of a good Salmonella control program. Sample results can help in the evaluation of the efficacy of cleaning and disinfection programs, whether or not there is a need to adjust an autogenous vaccine and how management practices affect the shed of Salmonella. He recommended that sampling should be conducted at peak times of stress for the birds, such as when they first go into lay or after vaccination. Be sure to sample next to boxes, he advised.



To wash or not to wash fertile eggs?



Keeping floor eggs to a minimum and picking those up regularly are an important first step in keeping eggs clean. Wooming said that Cargill has put more emphasis on nest box sanitation. Nest pads are dusted regularly now, more often than in the past. No biological soiling should reach the egg room.



Turkey companies routinely wash hatching eggs. Wooming said that Cargill is switching the type of egg washing machine that it uses on turkey breeder farms. He reports a 3.5 log reduction in total plate counts after washing the eggs with 400 parts per million of chlorine in the egg wash solution. Because of this high concentration of chlorine, the machine is vented to the outside.



Most broiler breeders, including Tyson, do not wash hatching eggs. Gustin said, "Washing eggs can work if done right, but if not it can be a train wreck. It can be efficacious."



Salmonella control in the hatchery


"Salmonella Enteritidis is a time bomb in a hatchery from pip through pull," Gustin said. "You will multiply and cross contaminate everything that comes in from the breeder farm at the hatchery. This is why SE vaccination is so critical."


Tyson fumigates egg rooms and eggs, but Gustin said it has little efficacy on coliforms.  " At its best you get a 1 log reduction through fumigation, with either periacetic acid or a glutaraldehyde and quaternary ammonia mix, at the hatchery," he said. Suppliers are aware of this and know that as antibiotic usage is restricted in the future the effectiveness of fumigation will become even more critical to early chick mortality.



Hatchery fumigation works



Cargill fumigates some of its hatchery equipment with formaldehyde. Even with the risks associated with handling and using formaldehyde, it is worth using because it works, according to Wooming.



Cargill has developed a mechanism for using formaldehyde that avoids employee exposure, so it is safe, he added. The days of just sticking liquid formalin on a plate in your hatcher are long gone, he noted.



No materials should be reused that have come in contact with chicks unless those materials have been cleaned and sanitized, according to Gustin. He said it is important to monitor tray wash water. Tyson's microbiological monitoring of hatchery sanitation is rigorous; around 300 samples each month are taken per hatchery.



Feed mill interventions



Feed is not part of the Salmonella problem in some of Cargill's complexes. "It is not the big bear that it is perceived to be," Wooming said. Sampling finished feed can establish whether or not feed is a problem and if it is, sampling of incoming ingredients and along all the steps in the process can narrow down areas that need to be addressed.



Controlling dust generated as feed ingredients are unloaded at the mill is important. If this dust is contaminated, it can contaminate finished feed if it makes its way to the pellet cooler or finished feed storage areas. Cargill uses vacuum tubes to suck up dust coming off the unloading area and keep the dust from getting into the feed mill.



In areas where the feed mill is part of the Salmonella problem, Cargill adds a blend of aqueous formaldehyde and organic acids to breeder feeds during times of maximum stress.



Pelleting of feeds effective in Tyson operations



Tyson's goal for its feed mills is for pellets to attain 180 F for 45 seconds. Gustin said that most of the mills do a good job of achieving this. He said that he doesn't think feed mills are a big source of Salmonella for Tyson now.



"You do need to check your feed ingredients, some are cleaner than you would think," he said. "Animal products, even eggs shell products, can be all right."



Windrowing, composting helps keep Salmonella levels down



"In the absence of colonizing or bad Salmonella serotypes, old or reused litter provides the best competitive exclusion that money can buy," Gustin said. Where built-up litter is used, he recommends windrow composting the litter between flocks. If done properly, composting can effectively reduce Salmonella numbers in the litter, he said. Litter composting can also have a positive impact on bird health and performance.



Turkey growers clean and disinfect brooder houses after each flock, and the goal is to get them as clean as the breeder houses. The side benefit of this has been better bird performance, according to Wooming. Cargill encourages growers to windrow compost built-up litter in finisher houses, particularly for the toms since they provide most of the inputs for ground turkey.



Keeping litter dry requires management



Keeping litter dry prevents Salmonella from proliferating, according to Gustin. Tyson tracks water usage in broiler houses on a daily basis. It is important for growers to maintain drinkers and foggers to prevent leakage. He also said that the sodium and phosphorous levels in the feeds need to be monitored in order to control house moisture. This is particularly important for veg-fed birds because of high soybean meal levels.



Gut health is essential to keeping Salmonella out



"Gut integrity and Salmonella prevalence go hand in hand; if you have poor gut integrity you don't have a prayer with Salmonella," said Gustin. This means that coccidiosis control programs must be successful.



Tyson has used competitive exclusion and organic acid products in broiler flocks. However, it is important to "get rid of the noise in the system" before evaluating these programs.  " We use a heat stable direct fed microbial religiously in our feed, and we think this is a big contributor to the gut health of our flocks," he said.



Cargill uses probiotics in its meat bird feeds and the company has changed probiotics once, according to Wooming. However, he said, "There is no silver bullet."



Indications that your Salmonella program is working



Does Salmonella control in live production operations bring benefits? In addition to lower Salmonella numbers arriving at the processing plant, Tyson has experienced a number of improvements in live performance that Gustin attributes to secondary benefits of good Salmonella control.


  • Good rodent control on farms has made prescriptions to treat breeder flocks with fowl cholera a rarity.


  • It is more difficult now to make new autogenous Salmonella vaccines, because it's more difficult to isolate Salmonella, particularly the worst offenders.


  • Seven-day chick mortality has improved.


  • Live haul equipment samples are negative for Salmonella.


  • Paw yield has increased because of better litter conditions.



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