Common house flies, beetles, rats and mice can carry the bacteria, so pest management in barns is critical
RED DEER, Alta. — When Susan Schafers was told that her Alberta egg farm had tested positive for salmonella, she and her staff shifted to high gear to evaluate bio-security.
Her farm at Stony Plain tested positive for Salmonella heidelberg and typhimurium strains. Both can make human sick, she told a poultry research forum held in Red Deer Feb. 27.
Her farm has seven barns that are five to 50 years old and biosecurity was not as tight as it could be within and between the buildings.
Close examination showed there were problems with mice, which can carry the bacteria.
Staff also had to learn the seriousness of the situation.
“If they find salmonella enteritidis on my farm and we are depopulated, your jobs are going bye-bye. They pay a lot more attention to things nowadays,” she said.
She spent thousands of dollars to control rodents and clean up the farm. The farm has been salmonella clear for two years.
In 2016, 600 tests for pullets and layers were collected in Alberta and about 40 percent came back positive for a general type of salmonella, she said.
These are routine samples collected through Egg Farmers of Alberta’s mandatory Start Clean- Stay Clean Program to monitor salmonella enteriditis.
If that strain is found, it means quarantines and flock depopulation, followed by cleaning and disinfection. Insurance is available but it does not cover all the costs, Schafers said.
Every farm has to be serious about salmonella because it can cause serious food poisoning, said Chuck Hofacre of the University of Georgia poultry diagnostic and research centre.
Salmonella are gram-negative bacteria, which means they can pass genes between each other. E. coli, salmonella and campylobacter can all do this and can pass on resistance or become more virulent.
There are about 2,500 different forms of salmonella so identification is important to make sure the bacteria are dealt with correctly.
It resides in the gut of the birds but does not harm them. It may be live in water, feed, wildlife, insects, rodents, fomites, humans, litter, hatchery and vehicles. It is unlikely to be eradicated.
“We are not going to make it disappear. Salmonella is a numbers game and each of the things we do will help us reduce the numbers,” Hofacre said.
Pest management is critical. Common houseflies, beetles, rats and mice can carry it so they must be controlled. When cleaning a barn, he recommends placing rodent baits, removing all litter and manure and washing and disinfecting with insecticides last to prevent beetles from returning.
Feed can be a source of the bacteria but that is rare.
“Everybody wants to blame the feed mill for salmonella,” he said.
The highest risk ingredient is animal byproducts, especially poultry meal, so these should be avoided, especially in breeder feed mixes.
Drinking water is rarely a source of salmonella but germs can spread among birds through the drinking supply. Flocks given chlorinated water at least once a week had significantly less salmonella.
He also advocates competitive exclusion and various products are available.
The gut of newly hatched chickens and turkeys do not have any bacteria. In the first few hours the gut bacteria starts to form to provide a natural barrier to harmful bacteria. When chicks were hatched under a hen, the flora in the feces of the mother helped establish beneficial bacteria in the chicks’ gut. With modern incubation they are not exposed to feces for that added immunity.
Hofacre advocates vaccination and new products like probiotics in feed to reduce salmonella.
Individual farms need to find the products that work best for them from reputable suppliers because nothing works perfectly all the time. Organic acid in water has been shown to reduce salmonella.
A coccidiosis vaccination also seems to help.
Salmonella tends to reside in the cecum of chickens and turkey.
“A low dose of cecal cocci makes the cecal wall thicker and it makes it harder for salmonella to colonize and get through and cause infection.”
Working with veterinarians, poultry producers have to remain diligent by understanding where the bacteria came from and how to control it.
“There is not one thing we are going to do that is going to eliminate salmonella. There is no magic potion. It takes a lot of elbow grease and a lot of work,” he said.