Violative residue cows
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Watch these cows for violative residues

August 10, 2016
POSTED BY: Gary Neubauer | DVM | Senior Manager | Dairy Technical Services | Zoetis

Nearly all violative drug residues detected in the milk supply are caused by on-farm mistakes.1 The causes of violative residues in milk often can be traced to treated cows that were milked accidently. 

There are three types of cows in the herd that have the most drug residue risk.1 They include:

  1. The recently treated dry cow
  2. The dry-treated cow that freshens early
  3. The treated lactating cow during her milk discard time

These cows have high enough levels of antibiotics to cause residue violations. To help avoid the mistake of milk from these types of cows entering the bulk tank, we recommend covering the following checkpoints on your dairy:

  • Complete an inventory of all drugs used on the dairy, including dry cow treatments, lactating mastitis tubes, injectable antibiotics and all other therapeutic substances.
  • Document the milk and meat withdrawals for each drug.
  • Review treatment records of all treated lactating cows and the dry period length of recently fresh cows.
  • Educate all individuals who milk the cows so they know how to properly milk treated cows and which cows shouldn’t be milked into the bulk tank.
  • Inspect all milking equipment for treated cows to ensure that contaminated milk is not inadvertently entering the bulk tank. Even a small amount of milk from a treated cow during her milk discard time could cause a violation.

We also recommend following the 10-point plan in the Dairy Animal Care & Quality Assurance guidelines. When producers and veterinarians work together to implement this plan, everything should be in place to minimize the chance of a residue violation occurring in the milk supply.

However, the benefits don’t stop at fewer violations. Among herds where this program has been incorporated, lower somatic cell counts and higher rolling herd averages also have been documented.1 Work with your veterinarian to implement the 10-point plan so a tanker load of milk isn’t found hot from your dairy.



1 Neubauer GD. Antibiotic Residues: Perception vs. Reality. Published May 22, 1996. Accessed June 9, 2016.




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