1. Guidelines for Antibiotic Residue Avoidance S. Andrew University of Connecticut

2. Why Should We be Concerned About Residues in Milk? About Residues in Milk? The goal is to produce a nutritious, wholesome food for consumers. It is essential to maintain and foster consumer confidence. Profitability

3. Human Food Safety Issues Sensitivity to antibiotics Immunological response Immunological response Bacterial resistance to antibiotics No link established between No link established between animal use and human pathogen animal 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)

4. Antibiotic Residue Defined as: Detection of antibiotic in milk: 1. at or above the tolerance or safe concentration for approved drugs, or concentration for approved drugs, or 2. at any concentration for unapproved drugs drugs 3. at any concentration for illegal drugs drugs

5. Antibiotic Routes of Administration Administration Intramammary Topical Oral skin Injectable feet Intramuscular teats Intramuscular teats Intravenous eyes Intravenous eyes Intrauterine Intrauterine Feed Additives Feed Additives

6. Major Use of Antibiotics is for the Treatment of Mastitis Intramammary Dry cow and lactation treatments

7. Top Five reasons for Residue Violations 1. Milking a treated dry or lactating cow cow 2. Same milking unit for treated and un- treated cows treated cows 3. One quarter treated, milk from other three quarters put in tank other three quarters put in tank 4. Unaware that newly purchased animals were treated animals were treated 5. Fresh cow milk contained residues from dry cow treatment from dry cow treatment

8. Why do Residues Occur? Lack of adequate record-keeping Lack of understanding antibiotic use use Poor relationship between producer and veterinarian producer and veterinarian Sischo, and coworkers, 1997 Sischo, and coworkers, 1997

9. Regulation of Antibiotic Residues in Milk Milk is regulated at the bulk tank/tanker Milk is regulated at the bulk tank/tanker truck level. truck level. Pasteurized Milk Ordinance (PMO) Pasteurized Milk Ordinance (PMO) a. under section 6 a. under section 6 milk is sampled 4 times during any milk is sampled 4 times during any consecutive 6 months. consecutive 6 months.

10. b. Under Appendix N of the PMO - every tanker truck is screened for beta-lactam antibiotics beginning July, 1992 Penicillin Cloxacillin Amoxicillin Cephaprin Ampicillin Ceftiofur - bulk tank also sampled

11. If the tanker truck sample is: Positive Negative sample re-tested no further 2x action if positive - traced re-tested at back to bulk tank State Lab Regulatory action $$$ Regulatory action $$$

12. Milk is analyzed for antibiotic Milk is analyzed for antibiotic Residues using Qualitative Residues using Qualitative Tests Tests The tests used have been evaluated and accepted by FDA for use with bulk tank/tanker truck milk. # of samples tested % positive # of samples tested % positive 1995 3,219,071 0.101% 1996 3,310,772 0.106% Smucker, 1997 Smucker, 1997

13. Therefore, approximately 99.9% of milk tested is free of antibiotic residues It appears that we are winning the race! However, 3,507 positive loads in 1996

14. How to Reduce the Risk of Antibiotic Residue Violations 1. Follow label directions for approved drugs (treatment regimen approved drugs (treatment regimen and withdrawal times) and withdrawal times) 2. Extra-label use of antibiotic only under veterinarian guidance only under veterinarian guidance 3. Identify treated animals and milk into separate bucket. into separate bucket.

15. How to Reduce the Risk of Antibiotic Residue Violations 4. Establish a herd health management program management program 5. Establish effective record-keeping 6. Education/communication with all personnel involved with milking personnel involved with milking and treating cows and heifers. and treating cows and heifers.

16. How to Reduce the Risk of Antibiotic Residue Violations 7. Follow the 10-point Milk and Dairy 7. Follow the 10-point Milk and Dairy Beef Quality Assurance Program Beef Quality Assurance Program # 2 Establish a valid veterinarian/client/patient relationship # 2 Establish a valid veterinarian/client/patient relationship #8 Use antibiotic residue screening #8 Use antibiotic residue screening tests for testing treated cow’s milk

17. Bulk Tank/Tanker Individual Truck Cow At Which Level Should Milk be Tested? Milk be Tested?

18. Ideally, screening milk from treated cows before adding the milk to the bulk tank is financially advantageous However, Many cases of residue violations Many cases of residue violations are due to accidentally milking are due to accidentally milking a dry-treated cow or treated cow a dry-treated cow or treated cowAlso……..

19. The screening tests have not been evaluated by FDA for use with individual cow’s milk Major concern is the potential for increased false - positive outcomes. Results in dumping acceptable milk.

20. The false-positive rate for screening tests used with individual cow’ milk ranged from: 0 % - 83% 0 % - 83% Cullor and coworkers, 1994 Cullor and coworkers, 1994 Andrew and coworkers, 1997 Andrew and coworkers, 1997 Sischo and Burns, 1993 Sischo and Burns, 1993

21. Screening milk from cows treated with an antibiotic following the appropriate withholding time Positive result may be due to: Positive result may be due to: 1. Antibiotic present above tolerance 2. Antibiotic present below tolerance 3. False positive outcome

22. Factors Affecting False-Positive Rates of Antibiotic Residue 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

23. Steps to Optimize Screening Test Performance for Individual Cow Milk Steps to Optimize Screening Test Performance for Individual Cow Milk 1. ESTABLISH AN EFFECTIVE MASTITIS CONTROL PROGRAM! MASTITIS CONTROL PROGRAM! 2. Follow drug withholding times. 3. Match the test to the drug. 4. Test visually normal milk.

24. Steps to Optimize Screening Test Performance for Individual Cow Milk 5. If result is positive, retest. 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 milk processor laboratory for testing. processor laboratory for testing.

25. Summary Residue Avoidance Understanding how antibiotic residues can occur can aid in residue avoidance Using residue screening tests

26. Summary Residue Avoidance Establish an effective herd health program Education and communication is essential

27. Goal! Goal! Producing high quality milk maintains consumer confidence