"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)