CS: Underperformance and Infectious Dz Flashcards
1
Q
Measures of beef performance?
A
- daily live weight gain (0.8kg/d, 1kg/d when weaning?)
- % in calf (>95%)
- more qualitative d/t block calving cf. dairy
- live calfs /no. cows put to bull (aim >95%, slightly cows cf. heifers)
- muscle: fat ration for grading carcasse
- involuntary culls
2
Q
Measures dairy performance?
A
- calving interval (aim 365 or 400d ish)
- growth rate (0.7kg/d)
- milk yield (~7,500l/cow/year average)
3
Q
Diseases affecting performance?
A
> biggest - mastitis - lameness > also - lepto - IBR - BVD - Neospora - Salmonella - Campy - Endometritis - TB - E. Coli - Johnes (^ prevalence) - SARA - Fatty liver/pregnany toxaemia
4
Q
Assessnig presence endemic dz
A
- Bulk milk tank sampling (Brucellosis serology also, mastitis cell count, low fat for SARA)
- CMT
- observation (lameness etc.)
- intradermal (eg. TB)
> check different age groups (if + serology only present older cows likely historic infection rather than active)
-
5
Q
How can disease be avoided?
A
- vax and isolate new stock
6
Q
How do different Johnes tests differ in sense and spec?
A
- milk higher sensitivity as threshold for + outcome lowered (cf blood)
7
Q
Effects of Neospora caninum ?
A
> losses d/t - v post weaning weight - v milk yield - premature culling - ABORTION > signs - often none - early embreyonic death (if infected
8
Q
How is neospora caninum transmitted?
A
- vertical and horizontal
> vertical - parasite migration during pregnancy to foetus from PI dams
- will affect several generations and successive pregnancies
> horizontal - dogs IH, cows ingest oocysts from feaces
- CAN BECOME pi
9
Q
Dx neospora caninum?
A
- histopath on aborted foetuses
- serology of dam or calf (if calf + assume dam also +, but PI animals Ab levels fluctuate so can get false -ves: Better test needed if trying to eradicate dz or maintain free herd
- PCR/IHC to differentiate from other protozoa on histo
10
Q
Is there a vax for neospora? Control/prevention?
A
- not currently
- cull infected cattle
- breed seronegative stock
- consider embryo transfer for infected stock high genetic merit
- dogs away from farm
- biosecurity at calving, dispose of placentas and aborted material
11
Q
Clinical effects of BVDV
A
- infertility (abortions/stillbirths/mummification)
- birth defects (weak sickly calves, neuro signs)
- ill thrift and stunted growth
- poor condition
- IMMUNOCOMPROMISE -> 2* infection; esp scours and pneumonia
- v milk yield
- mucosal dz if cytopathic form mutates (6-18mo)
- Better groups list **
- Naïve, non-pregnant, immunocompetent: no CS in 70-90%
- Acute: fever, lethargy, anorexic, ocular discharge, nasal discharge, oral lesions, diarrhoea, reduced milk yield
- Chronic: mucosal disease.
- In-utero infection: abortions, congenital defects (cerebellar hypoplasia) weak, small calves, unthrifty PI calves.
12
Q
Tests for IDing presence BVDV?
A
- Ab ELISA to see exposure of herd (bulk milk or bloods)
- PIs Antigen/viral RNA/virus isolation hunt: bulk milk or young stock bloods or ear notch 2 samples 3wks apart
13
Q
How can BVD potentially be eradicated on farm?
A
- eradicate PI reservoir
- vax all breeding females to prevent new PIs born (killed vax so 2 jabs needed, ensure well before 1st service eg. yearlings)
- booster each service
- with active infection may need to vax other stages +- dam few weeks before calving to ^ colostrol abs
- continue bloodm onitoring 12mo after last PI identified
- purchase animals from BVDV free herds or quarantine 1m and blood test
- isolate cows bought in calf until parturition then screen calves PI (trojan mother poss with variable ab titre but no active infection despite PI calf)
- prevent contact with neighbouring farms using double perimeter fence
14
Q
What can interfere with testing calves?
A
- MDA
- blood sample pre-colostrum or >4mo
15
Q
How else may BVDV be spread
A
semen
- PI bulls
- check semen before AI (not allowed to sell AI semen from BVD+ bulls but if DIY be careful)
