johne’s disease update: steve hendrick, dvm, dvsc thursday, april 14 th, 2005

Johne’s Disease Update:

Steve Hendrick, DVM, DVSc

Thursday, April 14th, 2005

Outline:

Johne’s Disease Background Impact on

Production Risk Factors

Conclusions

Johne’s Disease:

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 -548 193 <0.01*

milk ELISA positive -464 188 0.01*

serum ELISA positive -173 154 0.26

Controlled for: parity, DIM, SCC-LS, and herd.* significant at p<0.05

Culling:

Variable: Hazard Ratio:

P-value:

fecal culture positive

3.2 <0.01*

milk ELISA positive 2.3 <0.01*

serum ELISA positive

1.7 0.05*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 = $9,000

36 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)

$100-200 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 DiseaseMilk production (10 BCA points)

3.40.9

<0.01<0.01

Rumensin given to cows within last five yearsa 0.5 0.04

Pre-weaning Heifer Calves:Calves kept in hutches 0.5 0.03

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 hrSpringing Heifer Cleanliness:- Manure on hip, belly & udder

2.7

1.9

0.05

0.07

In herds with a history of Johne’s disease:

Risk Factors:

Variable:a OR: P-value:

Background:Purchase replacement cattle

3.2 0.05

Rumensin given to cows within last five yearsa 0.3 <0.01

Pre-weaning Heifer Calves:Calves kept in hutches

0.2 <0.01a 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?