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Implementing and Evaluating a Selective Dry Cow Therapy Program

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Pamela Ruegg joins us to discuss selective dry cow therapy. Learn about implementing and evaluating a program, as well as how to decide whether selective therapy might be a good fit for your operation. View the full presentation at https://www.youtube.com/watch?v=VKRAqHQZIng

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Implementing and Evaluating a Selective Dry Cow Therapy Program

  1. 1. Copyright ©2017 Pamela L. Ruegg, all rights reserved Implementing and Evaluating a Selective Dry Cow Therapy Program Pamela Ruegg, DVM, MPVM University of Wisconsin, Madison
  2. 2. Almost all Dairy Farms Use DCT • Standard mastitis control program – >80% of US herds treat 100% • most farmers treat most cows – 93% of cows receive DCT • Blanket dry cow therapy programs developed in 1970’s – >50% of cows had infected quarters • Today fewer cows are infected – Re-examination of use of antibiotics on dairy farms 0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100% None 1-33% 34-66% 67-99% 100% Proportion of Herds Using Dry Cow Therapy: USDA NAHMS 2002 2007 2014
  3. 3. Control of Contagious Pathogens has Been Effective • The prevalence of Staph aureus & Strep agalactiae has steadily decreased – Adoption of 5 point plan – Dry cow treatment • Environmental pathogens now cause most mastitis – Many mild clinical cases • Bulk tank SCC in US has dropped to about 200,000 0% 5% 10% 15% 20% 25% 30% 35% 40% 45% 50% 1994 1995 1996 1997 1998 1999 2000 2001 Proportionofisolates Year Isolation of Bacteria from >77,000 Milk Samples, WI, USA Staph aureus Strep agalactiae Makovec & Ruegg, 2003. J Dairy Sci
  4. 4. Purpose of Dry Cow Therapy is to Reduce Risk of Mastitis • Therapeutic – Cure cows with subclinical infected quarters at dry off – Can we identify cows that don’t need treatment? • Preventive – Prevent new infections during high risk period – Can we use non-antibiotic tools to protect these animals?
  5. 5. Therapeutic Function • SCC >200,000 cells/ml = evidence of mastitis • SCC does not increase with DIM unless the cow becomes infected • Many herds have >30% of cows with subclinical infections • Treatment of these infections is best performed at dry off • Increased efficacy • Reduced risk of drug residues • More economical – no milk discard 0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100% <30 31-150 151-250 >250 %ofCowswithSCC>200,000cells/mL Days in Milk Prevalence of Subclinical IMI 1 WI Dairy Farm with BTSCC 160,000 cells/mL Lact 1 Lact 2 Lact 3
  6. 6. Preventive Function • Keratin Plug is Primary Defense against IMI • Delayed formation of keratin plug • Open teats were found: – 40% (2 weeks) – 30% (4 weeks) – 24% (6 weeks) • Dingwell et al., 2003 • High production delayed formation of keratin plug – 50% of cows that produced >46 lbs. on day of dry off
  7. 7. Copyright ©2017 Pamela L. Ruegg, all rights reserved Selective DCT Means Use of Antibiotics &/OR Sealants • Purpose – Use antibiotics only to cows that have evidence of current intramammary infection • Selective dry cow programs – use IMM antibiotics only to treat cows infected at dry off – Use teat sealants to prevents new infections • Selective dry cow programs are NOT simply stopping use of DCT
  8. 8. What Does the Research Tell Us? • Recent research indicates that: – Selective DCT when randomly applied • Decreases antibiotic usage • Increases mastitis – Selective DCT when carefully applied in selected herds • Can decrease antibiotic usage without increasing mastitis • No evidence to date that: – Use of blanket DCT increases antimicrobial resistance – Use of selective DCT reduces development of antimicrobial resistance Rajala-Schultz et al., 2011 JDR 78:489 Scherpenzeel et al., 2014 S97:3606 Cameron et al., 2014 JDS 97:270 & 2014 JDS 97:2427
  9. 9. Copyright ©2017 Pamela L. Ruegg, all rights reserved Is SDCT appropriate for your herd? • Has your herd controlled subclinical mastitis? – Review the BTSCC history • Herds with BTSCC >250,000 cells/mL should continue to use blanket DCT program – Indication that a large % of cows have subclinical mastitis – Is your bulk tank free of Staph aureus & Strep agalactiae? • Do you have the ability to adequately monitor mastitis? – Monthly Individual cow SCC values – Forestripping to identify Clinical Mastitis & good CM records
  10. 10. Copyright ©2017 Pamela L. Ruegg, all rights reserved Methods for Identifying Cows with Active Infections • Review history of cow – Previous cases of clinical mastitis – Monthly SCC history • Perform individual quarter tests such as – CMT or SCC • Culture quarters
  11. 11. Which test is Best? • There is no perfect test – All tests have error • Which error means more to your herd? – Fail to treat infected cows? • This error is more common with use of culturing – Treat healthy cows? • This error is more common with non-culture based selection • Cows with increased SCC have evidence of ongoing infection – Using SCC history will maximize treatment • The false negative rate with culture is about 40% – Fail to treat infected ¼ Pantoja et al., 2009, Prev. Vet. Med 90:43
  12. 12. Which cows should be considered for SDCT? • Cows with – Monthly SCC >150,000 cells/ml at the last monthly test – History of CM within 90 days of dry off – SHOULD receive antibiotic DCT in every quarter • Selective dry cow programs reduce use of IMM antibiotics by about 50% • Those cows should still receive teat sealants
  13. 13. Cows Eligible for Teat Sealant only • Have no history of CM in last 90 days • Have SCC <200,000 cells/ml • Are CMT <2 on all 4 quarters • All quarters SCC <300,000 cells/mL • Internal or External Sealant? • Most research has evaluated internal sealants but… – Recent study used external sealant with good results • More research is needed
  14. 14. What Should You Monitor if you Use SDCT? • DCT is only given to multiparous cows • Increased SCC of IMI in Primiparous cows – Indicates problems with transition cow management – Not usually DCT problem • In multiparous cows not given DCT – SCC at 1st test should be <200,000 cells/ml • 85% of cows – Clinical mastitis in 1st month should be • <5% of cows • Culturing 1st week post-calving is not recommended – High rate of CNS infections that self-cure
  15. 15. What does Dry Cow Therapy Cost? 200 cow Dairy • Costs (per cow) – Orbeseal - $10.50 – SpectramastDC - $19.00 – Tomorrow - $10.00 • 200 cows * 85% – 170 cows dried off • Assumption is selective DCT reduces antibiotic usage by 50% $0 $1,000 $2,000 $3,000 $4,000 $5,000 $6,000 SpectDC Tomorrow Annual Cost of Products Used for Dry Cows DCT Only DCT & Orbeseal Selective (50% Less AB)
  16. 16. Costs of Mastitis: 200 Cows Baseline Scenario COST OF MASTITIS Herd Size (lactating) 200 Incidence Rate%/mastitis/mth 2% # of cases/month 4 Value of a milk cow $1,500.00 Avg Milk Production 80 Avg Milk Withhold in Days 8 Milk Price/ cwt $17.50 Avg # of IMM Tubes 5 Cost / tube $4.50 Death Rate of clinical mastitis 0.50% Avg cull wt 1,000 Cull Price/cwt 0.45$ Cull Price 450 Replacement cost 1,500.00$ Cost of a Cull $1,050.00 % culling/yr due to mastitis 10.00% Average Feed cost /cow/day $5.00 COST Herd/ MonthHerd / Year COW/ Year NonSaleable Milk $448 $5,376 $27 Production loss due to SCC$2,075 $24,898 $124 Total Drug Cost $90 $1,080 $5 Culling Cost $1,750 $21,000 $105 Death Cost $30 $360 $2 Mastitis Prevention Costs$2,463 $29,555 $148 Total Cost $6,856 $82,269 $411 Bulk Tank SCC = 195,000 15% of Herd > 200,000 Direct costs clinical: $135 36% of cost is prevention
  17. 17. Costs of Mastitis: 200 Cows Selective DCT – Mastitis Increases COST OF MASTITIS Herd Size (lactating) 200 Incidence Rate%/mastitis/mth 3% # of cases/month 6 Value of a milk cow $1,500.00 Avg Milk Production 80 Avg Milk Withhold in Days 8 Milk Price/ cwt $17.50 Avg # of IMM Tubes 5 Cost / tube $4.50 Death Rate of clinical mastitis 0.50% Avg cull wt 1,000 Cull Price/cwt 0.45$ Cull Price 450 Replacement cost 1,500.00$ Cost of a Cull $1,050.00 % culling/yr due to mastitis 10.00% Average Feed cost /cow/day $5.00 COST with DCT Herd/ MonthHerd / Year COW/ Year NonSaleable Milk $448 $5,376 $27 Production loss due to SCC$2,075 $24,898 $124 Total Drug Cost $90 $1,080 $5 Culling Cost $1,750 $21,000 $105 Death Cost $30 $360 $2 Mastitis Prevention Costs$2,463 $29,555 $148 Total Cost $6,856 $82,269 $411 Bulk Tank SCC = 223,000 25% of Herd > 200,000 Direct costs clinical: $135 COST NO DCT Herd/ MonthHerd / Year COW/ Year NonSaleable Milk $672 $8,064 $40 Production loss due to SCC$2,367 $28,409 $142 Total Drug Cost $135 $1,620 $8 Culling Cost $1,750 $21,000 $105 Death Cost $45 $540 $3 Mastitis Prevention Costs $2,296 $27,550 $138 Total Cost $7,265 $87,183 $436
  18. 18. Conclusion • The use of selective dry cow therapy can be effective in some herds but risks versus gains need to be assessed • Selection of cows that need to receive therapy is not a perfect science • Herds using selective therapy should have good post-calving surveillance programs • Reducing DCT to prevent antimicrobial resistance is unproven

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