Johne’s Disease Update: Steve Hendrick, DVM, DVSc Thursday, April 14 th, 2005

Outline:  Johne’s Disease  Background  Impact on Production  Risk Factors  Conclusions

Johne’s Disease:

Ontario Cows: 2.2%, Herds: 10% ( Tremblay et al., 2001) Cows: 7% (McNab et al., 1991) Atlantic Provinces Cows: 16% (McKenna et al., 2004) Cows: 1.6%, Herds: 17% (VanLeeuwen et al., 2001) Alberta Cows: 7% (Sorensen et al., 2003)

Prevalence: 50 randomly selected dairy herds: Milk Serum Cow-level: 1.7% 2.6% Herd-level*: 18% 30% * 2 or more positive cows per herd

Johne’s Disease: Production limiting disease Milk production, longevity, fertility, milk quality International trade barriers Crohn’s Disease ???

Production: Milk Production Decreased: Nordlund et al., 1996; Sweeney et al., 1994 Increased: McNab et al., 1991; Benedictus et al., 1987 Culling Increased risk Wilson et al., 1993

305-day Milk Production: Variable:Estimate (kg) SE:P-value: fecal culture positive <0.01* milk ELISA positive * serum ELISA positive Controlled for: parity, DIM, SCC-LS, and herd. * significant at p<0.05

Culling: Variable:Hazard Ratio:P-value: fecal culture positive3.2<0.01* milk ELISA positive2.3<0.01* serum ELISA positive * Controlled for: parity, DIM, milk production, pregnancy status, SCC-LS, and herd. * significant at p<0.05

Partial Budget: Assumptions: 100 cow dairy herd 10% fecal culture positive 10 infected cows + 90 non-shedding cows annual culling rate of 30% average milk price = $60/HL cost of a replacement heifer = $1,200 slaughter value: non-infected cows: $200 Infected cows: $0

Partial Budget: Culling: 1. Non-infected herd: 30% of 100 cows = 30 cows 2. Infected herd: 30% of 90 non-shedding cows = 27 cows 90% of 10 fecal positive cows = 9 cows 6 additional culls 6 x $1,200 per heifer = $7,200 extra for replacements 9 infected culls: 9 x $200 opportunity cost = $1,800 Sub-total = $9, cows

Partial Budget: Milk Production: 550 kg (5.5 HL) of lost milk for each infected cow (fecal culture) 10 cows x 5.5 HL/cow x $60/HL = $3,300 Total: $9,000 + $3,300 = $12,300 equates to $123 per cow ($100 USD) $ USD per cow (Ott et al., 1999) $49 per cow (Chi et al, 2002)

Other Johne’s Frustrations: Treatment: None are efficacious and cost-effective Diagnosis: Sub-clinical infections: difficult to identify - all tests lack sensitivity Prevention and Control: What are the important control points?

Johne’s Risk Factors: Calf housing and feeding Calving pen cleanliness Herd size and purchased replacement cattle History of clinical disease Housing of periparturient cows Soil type or pH Access to wildlife Cow nutrition and water sources

Variable:OR:P-value: Background: Previous Diagnosis of Johne’s Disease Milk production (10 BCA points) <0.01 Rumensin given to cows within last five years a Pre-weaning Heifer Calves: Calves kept in hutches a evaluated both premix and controlled-release capsule usage Johne’s Risk Factors:

Variable:OR:P-value: Background: Milk production (10 BCA points)0.9<0.01 Calving Pen: Calves removed >1 hr Springing Heifer Cleanliness: - Manure on hip, belly & udder In herds with a history of Johne’s disease: Risk Factors:

Variable: a OR:P-value: Background: Purchase replacement cattle Rumensin given to cows within last five years a 0.3<0.01 Pre-weaning Heifer Calves: Calves kept in hutches 0.2<0.01 a evaluated both premix and controlled-release capsule usage In herds with no prior history of Johne’s disease: Risk Factors:

Take Home Message: Prevalence of Johne’s disease in Ontario: Higher than previously reported 1 out of 3 farms are infected

Take Home Message: Production Impacts: Milk: loss of 150 to 550 kg (2-6%) Culling: removed 2 to 3 times faster Partial Budget: ~$120 per cow in the herd

Take Home Message: Prevention: avoid purchase of replacement cattle Control: maternity pen: reduce time in maternity pen by calf heifer rearing: housing of heifer calves springing heifer cleanliness monensin sodium usage ???

Acknowledgements:  Ontario Dairy Producers  Veterinary Practitioners  Advisory Committee:  Dr. Todd Duffield, Dr. Dave Kelton, Dr. Kerry Lissemore, Dr. Ken Leslie, Dr. Marie Archambault  Technical Assistants

Questions?