Nutrition and GI: Johne's Flashcards
What is the clinical disease of Johne’s?
- Older animals > 3yo
- Often after calving (stress)
- Profuse diarrhoea
- Weight loss
- Animals remains bright and eating
- Individual cases
What difference does Johnes make over a life time?
- Gives less milk- 4 tons
- 5x more likely to be lame
- 2x more likely to develop mastitis
- 1.8x more likely to suffer digestive/respiratory disease
When can transmission take place?
- 5% before birth- if dam clinical
- 80% new born calf- 0-4 weeks
- 10% young heifer
- 5% older heifers and cows
What are the infection routes in young calves?
- In utero
- Dirty environment
- Dam faeces- teats
- Dam colostrum
- Pooled colostrum
- Waste milk
What are the 4 stages of Johne’s?
- Stage 1- silent infection, calves
- Stage 2- sub-clinical disease
- Stage 3- early clinical disease- shedders
- Stage 4- advanced clinical disease
For every 1 stage 4 there will be upto 25 other infected animals
Average age of clinical signs is 5 years
What causes silent and shedding of Johne’s?
- Calf infected
- Cell mediated immunity protects and halts disease
- When disease progresses- antibody responds
- Further supresses CMI
- Causes shedding
What are the different diagnostic tools for Johne’s?
Faecal culture and/or PCR
* Detects shedders
* time and cost
ELISA
* Detects ab
* High probability of being shedder
* Sensitivity varies
Actiphage- phage used to bust open MAP to release DNA for PCR
* claims very sensitive
Gamma interferon- detects CMI- experimental
How is Johne’s target sampled?
30 cow screen
* Milk or blood ab
* Detects infection in herd
* Select- thin, mastitis, lame, poor yield, older
Instead of sampling whole herd
What is the gold standard for Johne’s in a live animal?
Faecal culture
* Slow and expensive
* Can intermittently shed
What are the 6 control strategies for national Johne’s Managment?
- Biosecurity protect and monitor
- Improved farm managment
- Improved farm managment and strategic testing
- Improved farm managment- test and cull
- Breed to terminal Sire
- Firebreak vaccination- doesn’t stop infection
What is the top level of CHeCS accreditation for Johne’s?
Cattle Health Certification Standards
- Accredit managed by MRO or labs
- 5 levels
- Level 1- 3 years of not animals positive in annual testing
What are the three types of ab testing?
- Quarterly- milk testing
- Single test- pre dry off
- Doube test- pre dry off and pre breeding
How do milk recordning companies classify Johne’s risk?
J0-J5
J0/1- low risk- max 1 negative
J2-4- moderate risk- previous negative, positive now
J5- repeat ELISA positive
What is a positive ‘Red’ cow?
Cow with optical density of 30 on the milk elisa in 2 sequential tests
Most get culled
Some continue with positive tests
Some never have another positive test
What is the name of the agent that causes Johne’s?
Myobacterium avium subspecies paratuberculosis
What is the importance of TB and MAP?
Cross reaction
* False positives/negatives
* Increase in MAP antibodies near TB test also
How can transmission to young stock be reduced?
- Reduce risk factors
- Cull animals likely to be shedding the infection
What risk factors can be reduced for Johne’s control?
- Avoid faeces
- Calving area- snatch
- Clean calving pens
- Calf pens/hutches
- Keep young stock seperate
- No pooled colostrum
- No waste milk feeding
- Slurry and manure on grazing
- Water courses- stagnant ponds
- Other hosts- sheep, deer
What are the different options when purchasing animals?
From low risk herds
* No history
* Test negative on at least 3 occassions
* ELISA test result for whole herd of origin
* ELISA individual- false confidence
* Faecal culture- better then ELISA
Can MAP be vaccinated against?
- Guidair- authorised in sheep
- Need APHA to use
- Administered in 2nd week of lfe
- Does not prevent infection
- Reduces incidence of clinical disease
- 2nd week of life
