Wednesday, May 6, 2015

The Truth About the Withdrawal Period for Wazine

"The egg withdrawal period for Wazine is two weeks."  - Statement found on a Facebook chicken group posted on May 5, 2015.

The two-week Food and Drug Administration approved label withdrawal time for Wazine® is specifically for meat, not eggs, and only for chickens (and turkeys) to which the drug is administered according to label instructions. There are two main reasons why this withdrawal time cannot be directly extrapolated to eggs from backyard chickens.

1. The disposition of the active ingredients, i.e. the rate at which they distribute to and deplete from meat and eggs, may differ. This can result in higher drug concentrations in eggs, requiring a longer withdrawal time.

2. The length of a withdrawal time is proportional to the dose administered to the chicken (the higher the dose, the longer the withdrawal time needed).  The actual dose of Wazine® that a backyard chicken receives may be higher or lower than the dose on which the label withdrawal time is based. This is because the product is administered through the chicken’s water or food. When determining the label withdrawal time, the source and amount of water and food can be tightly controlled to ensure a specific dose. But backyard chickens can obtain food and water from different sources, and their intake varies depending on several physiological, environmental and behavioral factors.

The use of a product like Wazine® in backyard egg producing chickens constitutes extra label use, and should therefore occur under the guidance of a veterinarian, who is responsible for ensuring that the withdrawal time is adequately extended to account for differences in drug dose and disposition.

Answer provided by scientists at the Food Animal Residue Avoidance Databank (FARAD)

Monday, May 4, 2015

The Truth About Salmonella

"You only get salmonella from chickens that are sick with it themselves. You would typically notice a salmonella problem in your flock."  - Statement found on a Facebook chicken group posted on April 30, 2015.

Salmonella can come from multiple sources, not just chickens.  You can get it from fruits and vegetables, as well as from your flock.  Cross-contamination in the kitchen is also another way to get sick with Salmonella, or any other bacteria for that matter.  If you do not keep certain foods refrigerated and then undercook the food,  then that is yet another way to get sick with Salmonella.  The blame is not always on the chickens!  Salmonella has lots of ways to get into us if we do not know how to safely handle foods in the kitchen.

Now that that is out of the way, let’s talk about the chickens.  You said “"You only get salmonella from chickens that are sick with it themselves.”  That statement is correct.  Salmonella on the inside of chicken eggs typically comes from the chicken that is sick with the organism.  However, you can get Salmonella on the outside of the egg if the coop that the egg is kept in contains Salmonella.  That means another chicken could be sick with Salmonella and be spreading it around in the coop.  Dirty bedding, dirty nest boxes, dirty egg collections baskets, or other surfaces in the coop can be a source.  We all know that our chickens tend to share nest boxes, so think about it.  If the infected chicken uses the same nest box as a healthy chicken, then the outside of a good egg can be contaminated just through contact.  That is why we wash our eggs, so that the bacteria does not work its way in through the eggshell’s pores to contaminate the inside (or our hands as we crack open the eggs).

You also said “You would typically notice a salmonella problem in your flock."  This is not as accurate as your previous statement.  Salmonella has several hundred different serotypes, very few of which cause the chickens to show symptoms of illness.  Instead the chickens can become carriers of Salmonella.  That means that they randomly shed the bacteria in their feces, and their eggs, without showing signs that they were ever sick.  Salmonella is famous for this feature in humans too.  Ever heard of Typhoid Mary?  Same bacteria, just in humans rather than chickens.  The only way we know if our chickens have Salmonella is to test them regularly, because if we lapse in our biosecurity, then our chickens can pick up Salmonella at any given time.

Response provided by Dr. Brigid McCrea, Ph.D.
Associate Professor and Extension Poultry Specialist

Delaware State University