Guidelines for Antibiotic Guidelines for Antibiotic Residue AvoidanceResidue Avoidance

S. AndrewS. Andrew

University of ConnecticutUniversity of Connecticut

Why Should We be ConcernedWhy Should We be Concerned About Residues in Milk?About Residues in Milk?

The goal is to produce a The goal is to produce a nutritious, wholesome foodnutritious, wholesome foodfor consumers.for consumers.

It is essential to maintain and It is essential to maintain and foster consumer confidence.foster consumer confidence.

ProfitabilityProfitability

Human Food Safety IssuesHuman Food Safety Issues

Sensitivity to antibioticsSensitivity to antibiotics Immunological responseImmunological response

Bacterial resistance to antibioticsBacterial resistance to antibiotics No link established betweenNo link established between animal use and human pathogenanimal use and human pathogen antibiotic resistance (however,antibiotic resistance (however, there is a potential for this to occur)there is a potential for this to occur)

Antibiotic Residue Defined as:Antibiotic Residue Defined as:

Detection of antibiotic in milk:Detection of antibiotic in milk:

1. at or above the tolerance or safe 1. at or above the tolerance or safe concentration for approved drugs, orconcentration for approved drugs, or

2. at any concentration for unapproved 2. at any concentration for unapproved drugsdrugs

3. at any concentration for illegal3. at any concentration for illegal drugsdrugs

Antibiotic Routes of Antibiotic Routes of AdministrationAdministration

Intramammary TopicalIntramammary TopicalOral Oral skin skinInjectableInjectable feet feet Intramuscular teatsIntramuscular teats Intravenous eyesIntravenous eyes IntrauterineIntrauterine Feed AdditivesFeed Additives

Major Use of Antibiotics is forMajor Use of Antibiotics is forthe Treatment of Mastitis the Treatment of Mastitis

IntramammaryIntramammary

Dry cow and Dry cow and lactation treatmentslactation treatments

Top Five reasons for Residue Top Five reasons for Residue ViolationsViolations

1. Milking a treated dry or lactating 1. Milking a treated dry or lactating cowcow2. Same milking unit for treated and un-2. Same milking unit for treated and un- treated cowstreated cows3. One quarter treated, milk from 3. One quarter treated, milk from other three quarters put in tankother three quarters put in tank4. Unaware that newly purchased 4. Unaware that newly purchased animals were treatedanimals were treated5. Fresh cow milk contained residues 5. Fresh cow milk contained residues from dry cow treatmentfrom dry cow treatment

Why do Residues Occur?Why do Residues Occur?

Lack of adequate record-keepingLack of adequate record-keeping

Lack of understanding antibioticLack of understanding antibiotic useuse

Poor relationship betweenPoor relationship between producer and veterinarianproducer and veterinarian Sischo, and coworkers, 1997Sischo, and coworkers, 1997

Regulation of AntibioticRegulation of AntibioticResidues in MilkResidues in Milk

Milk is regulated at the bulk tank/tankerMilk is regulated at the bulk tank/tanker truck level.truck level.

Pasteurized Milk Ordinance (PMO) Pasteurized Milk Ordinance (PMO) a. under section 6a. under section 6 milk is sampled 4 times during anymilk is sampled 4 times during any consecutive 6 months.consecutive 6 months.

b. Under Appendix N of the PMOb. Under Appendix N of the PMO

- every tanker truck is screened for- every tanker truck is screened forbeta-lactam antibiotics beginningbeta-lactam antibiotics beginningJuly, 1992July, 1992

Penicillin CloxacillinPenicillin CloxacillinAmoxicillin CephaprinAmoxicillin CephaprinAmpicillin CeftiofurAmpicillin Ceftiofur

- bulk tank also sampled- bulk tank also sampled

If the tanker truck sample is:If the tanker truck sample is:PositivePositive NegativeNegative

sample re-testedsample re-tested no furtherno further2x2x actionaction

if positive - traced re-tested atif positive - traced re-tested atback to bulk tank State Labback to bulk tank State Lab

Regulatory action Regulatory action $$$$$$

Milk is analyzed for antibioticMilk is analyzed for antibiotic Residues using QualitativeResidues using Qualitative TestsTestsThe tests used have been evaluatedThe tests used have been evaluatedand accepted by FDA for use withand accepted by FDA for use withbulk tank/tanker truck milk.bulk tank/tanker truck milk. # of samples tested % positive# of samples tested % positive1995 3,219,071 0.101%1995 3,219,071 0.101%1996 3,310,772 0.106%1996 3,310,772 0.106%

Smucker, 1997Smucker, 1997

Therefore, approximately Therefore, approximately 99.9% of milk tested is99.9% of milk tested isfree of antibiotic residuesfree of antibiotic residues

It appears that weIt appears that weare winning the race!are winning the race!

However, 3,507However, 3,507positive loads in 1996positive loads in 1996

How to Reduce the Risk of How to Reduce the Risk of Antibiotic Residue ViolationsAntibiotic Residue Violations

1. Follow label directions for 1. Follow label directions for approved drugs (treatment regimenapproved drugs (treatment regimen and withdrawal times)and withdrawal times)

2. Extra-label use of antibiotic2. Extra-label use of antibiotic only under veterinarian guidanceonly under veterinarian guidance

3. Identify treated animals and milk3. Identify treated animals and milk into separate bucket.into separate bucket.

How to Reduce the Risk of How to Reduce the Risk of Antibiotic Residue ViolationsAntibiotic Residue Violations4. Establish a herd health 4. Establish a herd health management programmanagement program

5. Establish effective record-keeping5. Establish effective record-keeping

6. Education/communication with all6. Education/communication with all personnel involved with milkingpersonnel involved with milking and treating cows and heifers.and treating cows and heifers.

How to Reduce the Risk of How to Reduce the Risk of Antibiotic Residue ViolationsAntibiotic Residue Violations

7. Follow the 10-point Milk and Dairy7. Follow the 10-point Milk and Dairy Beef Quality Assurance ProgramBeef Quality Assurance Program

# 2 Establish a valid # 2 Establish a valid veterinarian/client/patient relationshipveterinarian/client/patient relationship #8 Use antibiotic residue screening#8 Use antibiotic residue screeningtests for testing treated cow’s milktests for testing treated cow’s milk

Bulk Tank/Tanker IndividualBulk Tank/Tanker IndividualTruck CowTruck Cow

At Which Level ShouldAt Which Level Should Milk be Tested?Milk be Tested?

Ideally, screening milk fromIdeally, screening milk fromtreated cows before addingtreated cows before addingthe milk to the bulk tank the milk to the bulk tank is financially advantageousis financially advantageous

However, However, Many cases of residue violationsMany cases of residue violations are due to accidentally milkingare due to accidentally milking a dry-treated cow or treated cowa dry-treated cow or treated cowAlso……..Also……..

The screening tests have not The screening tests have not been evaluated by FDA for been evaluated by FDA for use with individual cow’s milkuse with individual cow’s milk

Major concern is the potentialMajor concern is the potentialfor increased false - positivefor increased false - positiveoutcomes. Results in dumpingoutcomes. Results in dumpingacceptable milk.acceptable milk.

The false-positive rate forThe false-positive rate forscreening tests used withscreening tests used withindividual cow’ milkindividual cow’ milkranged from:ranged from:

0 % - 83%0 % - 83% Cullor and coworkers, 1994Cullor and coworkers, 1994 Andrew and coworkers, Andrew and coworkers, 19971997 Sischo and Burns, 1993Sischo and Burns, 1993

Screening milk from cowsScreening milk from cowstreated with an antibiotictreated with an antibioticfollowing the appropriatefollowing the appropriatewithholding timewithholding time

Positive result may be due to:Positive result may be due to:

1. Antibiotic present above tolerance1. Antibiotic present above tolerance2. Antibiotic present below tolerance2. Antibiotic present below tolerance3. False positive outcome3. False positive outcome

Factors Affecting False-PositiveFactors Affecting False-PositiveRates of Antibiotic Residue Rates of Antibiotic Residue Screening Tests Screening Tests

Factors associated with:Factors associated with:

SCREENING TEST MILK _____SCREENING TEST MILK _____ - Test storage - Somatic cells- Test storage - Somatic cells conditions - Milk fat and protein conditions - Milk fat and protein - Operation of test - Milk sample - Operation of test - Milk sample

Steps to Optimize Screening Test Steps to Optimize Screening Test Performance for Individual Cow MilkPerformance for Individual Cow Milk

1. ESTABLISH AN EFFECTIVE 1. ESTABLISH AN EFFECTIVE MASTITIS CONTROL PROGRAM!MASTITIS CONTROL PROGRAM!

2. Follow drug withholding times.2. Follow drug withholding times.

3. Match the test to the drug.3. Match the test to the drug.

4. Test visually normal milk.4. Test visually normal milk.

Steps to Optimize Screening Test Steps to Optimize Screening Test Performance for Individual Cow MilkPerformance for Individual Cow Milk

5. If result is positive, retest.5. If result is positive, retest.

6. If positive again, check milk quality 6. If positive again, check milk quality and re-test in 24 hours.and re-test in 24 hours.

7. If positive, send milk sample to milk7. If positive, send milk sample to milk processor laboratory for testing.processor laboratory for testing.

SummarySummary

Residue AvoidanceResidue Avoidance

Understanding how antibiotic Understanding how antibiotic residues can occur can aid inresidues can occur can aid inresidue avoidanceresidue avoidance

Using residue screening testsUsing residue screening tests

SummarySummary

Residue AvoidanceResidue Avoidance

Establish an effective herd healthEstablish an effective herd healthprogramprogram

Education and communication isEducation and communication isessentialessential

Goal!Goal!

Producing high quality milk Producing high quality milk maintains consumer confidencemaintains consumer confidence