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
