Int’l - Salmonella Can Cause Poorer Eggshell Quality
Published:March 31, 2005
Source :Farming Life
A decrease in eggshell quality is a trait that may be used to detect chickens infected with Salmonella, according to recent US research.
ARS (Agricultural Research Service) veterinary medical officer, Jean Guard Bouldin, found an interesting phenomenon - not only was Salmonella present inside chicken eggs, but other bacteria were there also.
Since these bacteria are usually seen in eggs that have been contaminated through cracks in the shell, Bouldin theorized that poor eggshell quality allowed the bacteria to enter the egg.
Salmonella enteritidis is hard to detect in chickens because there are no symptoms. This poses a significant problem because the bacterium, found inside the egg, is an important cause of human foodborne illness.
Bouldin and colleague, Jeff Buhr, conducted tests in which chickens were inoculated with S. enteritidis.
Eggs were then tested for hardness by compressing them until a hairline crack formed. Eggs from Salmonella-infected hens cracked easier than those from non infected hens.
Other research has shown that some strains of S. enteritidis seem to target the hen's reproductive tract, which appears to result in an egg with a less resilient shell, according to Bouldin.
At low-dose infection, Bouldin found that S. enteritidis actually stimulated egg production, particularly in older hens. This increased production may have stretched the limited eggshell material - calcium - a bit too thin, literally.
Other diseases of chickens can also decrease shell quality, but usually they result in a decrease in production and illness in hens.
Changes to eggshell quality over the lifespan of a laying hen are to be expected, and thus a hen's age could be an additional risk factor.
