The Department of Primary Industries and Fisheries reports a recent case involving treatment of calves with gentamycin. The veterinarian had noted a laboratory test report that identified that gentamycin was the only effective antibiotic against the cultured bacteria. The gentamycin treatment stopped deaths and was effective from an animal welfare viewpoint.
However, these calves were intended for a feedlot and eventually for the human food chain. Gentamycin's label states that it should not be used in food producing animals. This label instruction is there for a reason. An article in "FDA Veterinarian" (May/June 2003, pages 8-9), reported that calves treated with gentamycin resulted in residues 18 months later. Gentamycin binds to the kidney tissue of cattle and the actual withdrawal period is unknown and may well be measured in years.
In this particular case, a voluntary agreement is being negotiated through which these calves will be used as embryo transplant recipients and will not enter the food chain where they could cause trade problems.
Australia has a "National Residue Survey" that tests a wide range of foods for chemical residues, including antibiotics that are banned in food producing animals. The kidneys of cattle are collected from domestic and export abattoirs and tested.
In addition, a large proportion of our beef exports go to countries with highly sophisticated laboratories and consumers that are very sensitive to antibiotic residues, for example Japan and Singapore. Any detection of gentamycin in export beef would probably result in the rejection of all exports from that particular export abattoir, and perhaps even wider restrictions.
A similar ill-advised treatment could mean that an export abattoir could no longer supply their major market. The abattoir may need to temporarily shut down, with associated loss of jobs. This might all be traced back to the time some sick calves were treated with gentamycin.