Antibiotic Residues and Vaccines

– William P. Shulaw DVM MS, Extension Veterinarian, Beef/Sheep, The Ohio State University

Nearly every producer is aware of the need to observe withdrawal times when they use antibiotics in order to prevent antibiotic residues in harvested animals. However, many people are not aware that many commonly used vaccines contain antibiotics as preservatives. For example, the label of one product very commonly used for prevention of respiratory disease contains these precaution statements: “contains gentamicin as a preservative” and “Do not vaccinate within 21 days before slaughter.” Usually this is not a real concern because there is no immediate intention to sell the animal anyway. But sometimes things don’t go the way we planned – the vaccinated cow we planned to keep injures her udder; the healthy steer we just vaccinated gets ridden by a pen mate and is injured and needs to be salvaged; the feeder calf vaccinated as a requirement to go to the fair ends up getting slaughtered instead of put in a feeding program; and so on. In these cases there is a real potential for the animal to carry antibiotic residues to the processing plant where it may be tested for residues before slaughter.

The kidney is the site often tested for residues even though it isn’t consumed in the amount that muscle tissue is. Residues of some antibiotics, like gentamicin, can persist in the kidney for very long times. Presently, processors are sometimes allowed to use carcasses whose kidneys show low residues of certain antibiotics but whose muscle tissue tests negative for antibiotics. Recently, the Food Safety Inspection Service has indicated that they may no longer allow this policy and the entire carcass may be condemned. If this occurs, it is likely that processors will not be willing to absorb this loss and will attempt to place the responsibility some place back in the marketing chain – like the producer. It is important to READ THE LABEL on all products we use and to be sure we understand the directions for use and all the precaution statements. It will become increasingly important that we keep good records of ALL products we use, not just on our fed and feeder cattle, but also on our market cows and bulls. A major part of any Beef Quality Assurance program is responsible drug and vaccine use. Most problems in that area can be prevented by doing two things: READ THE LABEL and keep good records.