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117 Cards in this Set
- Front
- Back
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what is the overall aim of GIT nematode control in cattle?
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"the main aim is to avoid [L3] ingestion. If treating clinically affected cattle is it too late.
- mainly ML-resistant cooperia |
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describe the preventive drenching system in spring-born dairy calves
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"- similar approach to sheep
- aim to avoid autumn/early winter peak - prevent the early season contamination - treat regularly from weaning (5-6 months) - interval varies depending on product and its persistent activity - ML kills Ostertagia for 5-6months, but must give every month for Cooperia (no refugee of ostertagia) - if using short acting anthelmintic such as BZ or BZ+Lev combo then every 4w |
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what are the (dis)advantages of preventive drenching system?
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"advantages
- minimises subclinical effects - increase growth before winter - relatively low cost and reliable outcome - benefits > cost - independent of management - reduces parasite challenge for older cattle disadvantages - total reliance on anthelmintics - neglect of other factors e.g. good nutrition |
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how does protective drenching compare to protective drenching?
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"protective drenching occurs later to animals considered to “need a drench”
the peak of larvae count on grass is higher it is better to use preventative drench until immune response kicks in, then use protective drenching strategically when you need to. |
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describe and explain the different systems of rotational grazing to manage parasites in dairy calves:
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"“Ruakura system”
- aim: avoid drenching cattle - shifts calves every 1-2 days over the whole farm - not always possible - effective: frequent moving avoids reinfection from shed eggs —> L3 Irregular system - shifts at varying intervals - probably creates hotspots - parasite problems - need drenching programme. excessive challenge to cows. |
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describe and explain other grazing systems in cattle to manage parasites:
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"set stocked 2-4 calves per paddock
- cows move through leaving calves - usually from when vaccination complete - minimal drenching required (drench before dividing) - need to keep adequate feed but usually not a problem “Run-off” - grazing area away from main farm - most commonly used to take calves in May (9months) and return in-calf heifers at about 21months - many variations - sometimes used for dry cows and to conserve feed on main farm - potential problems - usually young stock only: can get heavily contaminated so may be dangerous all year - out of sight, out of mind - good drenching programme required + good nutrition Spelling pasture - timing: how long is enough? - dung pat excellent reservoir of [L3] - moist inside - usually not feasible in NZ as grass will get out of control - hay/silage aftermath is the best option - safe but not worm free - risk of overgrazing |
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what are the main issues with and how can parasites be managed in bull/beef contract-rearing dairy heifers?
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"- bringing in successive groups of young stock
- heavy reliance on drenching: need regular programme - preventive scheme - endeavour to utilise other classes of stock but often none available - widespread ML-resistant C.oncophora - use BZ+Lev combination: less convenient than pour-on ML - important to drench calves/older cattle on arrival - quarantine drench, then triple drench and put on “dirty” pasture to dilute/compete resistant worms - transportation, diet change may trigger Type 2 ostertagiosis |
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describe and explain the cow-calf system to manage parasites in cattle:
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"- calves weaned at 4-8 months (Feb-May)
- not normally drenched until weaning - can be significant parasitism before - while on mum, cows help keep down [larvae] on pasture. should still do regular treatments. - 3-4 treatments after weaning advised - interval affected by drug and formulaton |
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what is some evidence supporting worm treatment impacting production?
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"MSD field trial:
treated with 1x ivermectin injection: 0.2kg/day treated with 4x ivermectin injection: 0.4kg.day treated with 6x ivermectin injection: 0.5kg/day |
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what factors need to be considered when choosing a drench?
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"- consider anthelmintic resistance status on that farm
- early drenches: effective against Cooper - late winter: effective against Ostertagia |
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what is the current situation of anthelmintic resistance in cattle?
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"- beef certainly. Dairy possibly worse
- Cooperia oncophora main problem - BZ and ML resistance - so far LEV is working - Ostertagia - BZ resistance - ML resistance first few reports - LEV dose limiting species. Poor, especially against inhibited L4 - T.axei and T.longispicularis - some resistance |
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mode of delivery (anthelmintics): pour on vs oral or injectable?
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"- MLs and LEV
- available as pour-ons - ML dose rates: - pour on: 0.5mg/kg - injectable: 0.2mg/kg - pour ons: - farmers favour - issue: cattle licking product off back; penetrating into skin |
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what is the management protocol against Type 2 Ostertagiosis?
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"- prevention
- good parasite control to limit (L3) on pasture - late winter/early spring: preventative Rx to kill EL4 - MLs best anthelmintic - pour-ons no WHT for milk - most problems: younger animals, 12 months - can still see in older, but less common - routine treatment older dairy: small response - Eprinomectin and Moxidectin: increase milk volume, MS (fat, protein); 2yo in calf sooner - 0.03kgMS/day ~7.5kg MS —> 10 fold return - anti-ostertagia Ab levels in milk suggests we are losing production to worms. - overall: no significant effect. |
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main causes of poor growth in lambs:
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"- poor nutrition
- quality and or quantity - internal parasites - trace element deficiencies - cobalt, selenium - disease; pneumonia - enzooitc pneumonia in sheep common in NZ esp warmer regions - December-May |
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"- chronic “non-progressive” pneumonia |
- >20% lung affected - decreased growth are - pleurisy: inflammation of pleurae - would normally only affect growth rates of smallish proportion of the mob
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pneumonia: microorganisms associated with ovine pneumonia
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"bacteria
- Manneheimia haemolytica - Pasteurella multocida - Pasteurella trehalosi - Bordetella parapertussis Mycoplasmas - Mycoplasma ovipneumoniae - Mycoplasma arginini Viruses - Parainfluenza Virus Type 3 - Respiratory Syncytial Virus - Ovine adenovirus type 6 - Bovine adenovirus type 7 - unidentified cell associated agent |
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pneumonia: Suggested pathogenesis
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"Pasteurella?Manneheimia commensals in upper respiratory tract
lung defences compromised by viruses, Mycoplasma heat stress induced open mouth panting combination of young sheep, open mouth panting, dust lung damage from viruses/Mycoplasma allows Pasteurella/Mannheimia to colonise |
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what might cause stress and open mouthed panting in young sheep?
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"docking
mustering yarding - drenching, vaccinations weaning shearing |
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pneumonia: Risk factors ID’d at slaughter
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"difficult to define as the condition is only identified at slaughter
- shearing lambs on day of weaning - shearing lambs twice - frequent yarding post-weaning - motorised mustering - increased age of lambs at slaughter |
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pneumonia: Diagnosis
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"- history esp management
- range of clinical expression - mild: nothing seen - moderate: coughing, ill thrift, some deaths - severe: sudden deaths - observation at a distance - coughing - clinical examination of affected lambs - auscultation - necropsy - slaughter-house surveillance - report pleurisy |
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pneumonia: treatment
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"- antibiotics may suppress development and give partial recovery
- generally unsatisfactory - chronic lung abscesses may result |
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Pneumonia: prevention
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"- yard in the morning: cooler
- wet yards: reduce dust - cull bad animals: more likely to pick it up and spread through the flock - reduce yarding frequency: multiple procedures at one time - enough labour to minimise animals’ time in yards |
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Pinkeye: proper term, cause, morbidity
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"- Ovine infectious keratoconjunctivitis
- bacterial cause - Chlamydophilia - associated with dust, wind, flies - more common in summer and autumn - Mycoplasma - probably carrier sheep - not seasonal - transmission: direct contact and fomites - can be severe, can get recurrence - 10-20% morbidity, |
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pinkeye treatment
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"chlamydophilia
- may resolve spontaneously mycoplasma - oxytetracyclin SC/IM - oxytet in solution: in eyes - may recur |
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entropion
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"inversion of the eyelid
common in new-born lambs thought to be inherited |
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entropion: treatment
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"evert eyelid
- mild: manually - inject antibiotic in lower eyelid - remove elliptical section of skin under lower eyelid - Michele clip under lower eyelid - cull carrier ran (if identifiable) |
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what are the health challenges facing NZ pastoral livestock?
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"- Primary food source is pasture, so it is at risk of:
- under nutrition - trace element deficiencies - internal parasites and soil bacteria - toxic plants - management: rotational grazing and strip-grazing. Meaning there are high stocking densities - potential rapid transmission of infectious diseases - large flock/herd sizes - easy for problems in individuals to go un-noticed - periods of acute severe stress - mustering, yarding, shearing, trucking - other than that, a “relaxed” lifestyle - Outdoors all year round: exposed to extremes of weather - mortality of new-born lambs during storms - warm, moist, climate - fungal diseases in pasture - rapid development and good survival of parasites - fleece provides a warm moist micro-climate - flies, bacterial conditions - generally fed monoculture, often exposed to sudden ∆ - subject to wounds and abrasions which may predispose to infection/disease - deliberate: tail-docking. deep anaerobic wound where ring is placed —> increased susc. to tetanus - accidental: sharp object |
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where should the focus be when dealing with flock/herds?
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"Big flocks/herds mean low’ish profitability
- focus on flock/herd health rather than individual - focus on prevention of poor production/disease rather than treatment - focus on subclinical as well as clinical - integrate animal health with husbandry and consideration of the farm business |
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where is usually the issue in a production/poor health pastoral livestock system?
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most production or poor health issues in a pastoral livestock have a large management or husbandry component
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define the 7 steps in the herd/flock investigation
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"- Define the problem
- History taking - a.) environmental examination b.) distance exam 4. a.) Individual animal exam b.) +/- post mortem exam 5. ancillary aids/further diagnostic tests 6. Data analysis and decision making - short and long term 7. reporting back and future monitoring |
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explain the 1st step to the herd/flock investigation
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"1. define the problem
What what where when why use data if available, be specific |
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explain the 2nd step to the herd/flock investigation
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"2. History taking
on-going throughout investigation most important part!! Asks “How” for the 5 w’s differential diagnoses |
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explain the 3rd step to the herd/flock investigation
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"3. a) Environment examination
observational skills v.v imp begins as soon as you drive onto the farm 3. b) distance examination RR, hunger, BCS, behaviour, scouring, discharge, coughing, obvious cuts/injuries/swellings, variation in size |
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explain the 4th step to the herd/flock investigation
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"4. a) individual animal exam
- individuals that are clearly sick or badly affected - can undertake some procedures on large number relatively quick - eg MM, BCS, weighing 4. b) +/- PME - read animals +/- euthanasia of severely affected - large numbers, low individual value - consider sample size - “on the spot” diagnoses for many diseases - collect samples for further analysis |
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explain the 5th step to the herd/flock investigation
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"5. ancillary aids/further diagnostic tests
- collect correct, appropriate number of samples - compromise between cost and quality information Note: “i’ll do bloods” insufficient answer |
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explain the 6th step to the herd/flock investigation
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"6. Data analysis and decision making
Decide: - is an abnormality present? - if so, what? - is treatment possible or warranted? - may be better to focus the attention/funds on control and prevention - how can the problem be prevented/minimised? - short/long term - many production problems related t management: - intervention or change to management required for long term prevention |
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explain the 7th step to the herd/flock investigation
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"Reports are useful:
- clarify thoughts (for you and farmer) - written document that can be referred back to - poor record keeping often a problem in LA practice Future monitoring - correct course of action in many cases - on-going contact with farmer - may lead to further work/greater involvement |
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what issues can arise in the mating area that affect reproduction?
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"- long WOI (interval from weaning to service) due to:
- poor nutrition during lactation - cycling before weaning - mycotoxins - Poor farrowing rate due to: - EED —> infertility, delayed returns - disease: parvovirus - small litter size, infertility - poor timing of matings - overusing boars - poor semen handling - post-service discharge syndrome - mating late |
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what issues can arise in the dry sow area that affect reproduction?
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"- poor FR due to:
- early pregnancy stress - (embryo loss —> small litters, delayed return) - later pregnancy stress - (abortion) - disease (—> abortion) - eg lepto - long farrowing interval - failure to detect returns —> high NPDs, NIPs - low weaning weight - poor nutrition —> poor lactation - high stillborn - overfeeding sows —> fat sows —> farrowing problems |
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what issues can arise in the farrowing area that affect reproduction?
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"- low weaning weights
- farrow in poor condition - poor nutrition (lactation) - disease - high PWM (—> low numbers weaned —> loose $$) - starving piglets - mastitis - overfeeding sows - poor fostering - scours - poor hygiene and management - disease - high stillborns - farrowing difficulties |
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summarise the reproductive disorders of pigs into 5 failures:
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"- failure of sows and gilts to show heat
- failure of sows and gilts to be bred - failure to conceive when bred - failure to maintain pregnancy - failure to produce good litters |
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common health issues in pigs that affect reproduction?
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"- parvovirus
- enterovirus - original cause of SMEDI - no vaccines available - leptospirosis - encephalomyocarditis - toxoplasmosis - mycotoxicosis - seasonal infertility - Discharge: - vulvar discharge - cystitis - uterine infection discharge - vaginal infection |
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parvovirus in pigs: transmission, clinical signs, diagnosis, prevention/control
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"- Oral-nasal infection
- clinical signs: - males + non-pregnant females = none - SMEDI (stillbirth, Mummification, Embryonic Death, Infertility): spreads slowly from foetus to foetus - <30d = I, ED - 30-70d = M, ED - >70d = S, WP - Diagnosis: - clinical signs - detection of viral Ag’s in foetus - sow serology = little value - Immune sows pass on high levels of Abs to piglets that last for 3-6m - prevents infection and seroconversion of young pigs - interferes with vaccine in young pigs - prevention/control - natural infection (= lifelong protection) - vaccination (protection only 1-2y) |
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leptospirosis in pigs: transmission, clinical signs, diagnosis, treatment
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"- spread in urine (long term shedding), reproductive discharges
- infection via MM or broken skin - Clinical signs - reproductive disease: - abortions (+2-4w), stillbirths, weak piglets - sow: usually sub-clinical, sometime pyrexia and anorexia - diagnosis: - serology (MAT) - titres 1:1600+ (diff from vaccine titre) - culture not routinely done - Treatment: - Antibiotics, isolation - streptomycin , oxytetracycline |
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Mycotoxicosis
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"- effect depends upon stage of exposure, toxin level
- Zearalenone - “reproductive failure syndrome” - M, irregular returns to service, reduced litter size, deaths - rectal prolapse, swollen vulvas on newborn gilts, splay-legged piglets |
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Mycoplasma suis: transmission, clinical signs, treatment
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"- spread by direct exposure, blood components and blood sucking parasites
- clinical signs: - causes anaemia - associated with illness in periparturient sows - hyperaemia, oedema, swelling of vulva around farrowing - sub-optimal reproductive performance - treatment: - oxytetracycline |
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Discharge: types, differentiating, treatments
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"most common bug: E.coli
- cystitis: - discharge at end of urination - small volume (<20mL) - no systemic illness (unless ascends to kidneys) - urine pH >8 - blood and pus in urine - treat: - amoxicillin - clean living conditions - uterine infection: - discharge unrelated to urination - large volume (>100ml) - w/i 6d of oestrus - no systemic illness - treatment: - cull - vaginal - moderate volume ~50ml - unrelated to oestrus and reproduction - common in gilts |
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why do breeding soundness in bulls?
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"management
- reducing the risk of having fertilisation failure - risk of exacerbating infertility with poor quality sires |
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what does a breeding sounds examination entail?
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"- ID
- service testin/ observation of coitus and penis - scrotal circumference - palpation of genitalia - semen examination |
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which is more favourable: service testing or clinical/semen evaluation?
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"depends on aim of farmer.
service testing: - usually more appropriate for beef industry - most concerned whether bull can serve clinical/semen evaulation - usually most appropriate for dairy industry - most concerned about conception rates opposed to breeding bahaviour |
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list the steps of completing a bull soundness examination:
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"- general inspection, feet, legs, BCS
- scrotal circumference - clinical examination of genital - scrotal contents, accessory sex glands (vesicular glands) - behaviour, locomotor system - service test - semen examination - final assesments |
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what are some abnormalities of the locomotor system leading to “unsound” BSE?
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"impaired mounting or service behaviour
- foot - temporary: abscess, overgrown - permanent or congenital: malformed claws - back: - spondylitis: excess Ca2+ leads to increase bone deposition across vertebral bodies - upper limb: - less common |
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what are the penile lesions affecting service due to impaired mounting?
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"- ruptured penis
- oedema and pre-scrotal swelling - compromised vascular drainage - pain in genitalia BoHV-1, orchitis, seminal vesiculitis - temporarily unsound - inability to achieve intromission |
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what are the penile lesions affecting service due to mounting without intromission?
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"- Vascular defects:
- abnormal venous drainage - bv’s drain to corpus cavernosum - age: occlude. drain via root of penis - can’t get erect - blockage of longitudinal canals - penile deviations - frendulum fails to break down, pulls penis down - temporarily unsound - spiral deviations of the penis - corkscrew upon ejaculation = normal - corkscrew upon touching cow = abnormal - adhesions: - post BoHV-1, post trauma, penile neoplasia (fibropappilomata) - papillomas (can be temporary —> unsound) |
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what are issues that affect service by achieving intromission but failure to ejaculate
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"- neural damage: sensory nerves of the penis, spinal sensory nerve roots
- seminal vesiculitis (acute stages) - back pain (spondylitis) in mature bulls. usually progressively worsens, with acute episodes |
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what are the major syndromes causing lowered semen quality?
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"- testicular degeneration
- immaturity and overuse - young bulls: small production capability. immature sperm ejaculated - sperm defects - knobbed, dags, diadem, tail stump |
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what characteristics are attributed to a “sound ram”?
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"the ability to:
- successfully locate ewes - perform the act of mating - fertilise the ova with a net result of achieving pregnancy in the ewe actual mating behaviour rarely a problem - exception: young rams raised away from ewes |
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How do soundness exams test for fertility
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"they don’t.
eg monorchids are fertile but permanently unsound |
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what does a ram breeding soundness exam involve?
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"- palpate with both hands from behind the ram
check for: - anatomy of all structures within the scrotal sac - testis, epididymis (head, body, tail), spermatic cord - testicular symmetry - testicular tone - 29-35cm - testicular freedom from scrotal adhesions/ abscesses - spermatic cord - scrotal skin - heat releaser: should be think skin and small wool length - chorioptic mange - presence of abscesses or shearing cuts |
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when are ram soundness exams performed?
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"- pre-mating (Feb). 8w prior to PSM
- Pre-Sale (Oct) - Ram lambs at weaning to detect genetic trends from sires + can cyll non-suitable stud rams at premium abs prices rather than as 2t - Pre-purchase examination of a single sire = full individual fertility check - Failure of a ram(s) detected at next seasons lambing - detection of ram epididymitis lesions by client or by yourself following a fertility investigation |
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what is the aim of a ram soundness exam?
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"to determine the rams Category of Soundness and whether it should be used for this seasons mating
A genitally sound ram: - one that has no congenital, physical or genital abnormalities or any condition that will lead to this ram becoming incapable of service A fertile ram: - Is a ram that is capable of service and able to impregnate ewes mated to him can only be classed “At time of examination"" |
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what are the categories of soundness?
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"Sound:
- free from all defects of the genitalia and can be judged at time of clinical examination as fit for mating and able to be sold Temporarily unsound: - has a defect that can be treated returning the ram to full soundness for mating and sale Unsound: - has an untreatable defect that will impair his mating performance |
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what are the cases of testis degeneration (testis atrophy)?
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"- Seasonal atrophy
- out of season can be 1/3rd size due to decreased testosterone and decreased spermatogenesis - malnutrition - stocking rates/feet/teeth - Parasitism - —> poor BCS and atrophy - Heat - decreases spermatogenesis —> atrophy - excess wool length (>10mm) - dags - environmental temp: over yarding/transportation in summer - Chorioptic Mange causes exudative dermatitis of scrotal wall - diseases: fly strike, pnuemonia - fever - Disease of scrotal contents - Epididymitis - Anatomical - segmental aplasia - short scrotum lambs - vasectomised rams |
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what are examples of anatomical irregularities?
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"- asymmetry
- segmental aplasia - hypospadia - incomplete closure of the urethra: scrotal, mid-penis, end-penis - high riding scrotum - inguinal hernia - monorchid - micro-orchis - cryptorchid |
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what are the main 4 diseases of testis?
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"epididymitis
- Brucella ovis - Gram -ve Pleomorphs Chorioptic Mange - Chorioptes bovis CLA Abscesses - Corynebacterium pseudotuberculosis Trauma to scrotum - shearing cuts |
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what are the further examinations that can be done to investigate ram soundness?
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"- penis and prepuce examination
- for individual animals for sale or purchase - or animals with question to performance history NOT routine Anatomy: - sigmoid flexure, body of penis, glans penis, urethral process, - smooth and even - prepuce entire with no ulceration/wound preventing penile extrusion |
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what are some prepucial conditions that should be documented?
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"Posthitis
- infection limited to exterior of prepuce Balanoposthitis - Infection penetrated deep into prepuce (lay term = puzzle rot) - From Corynebacterium renale - transmitted by direct contact - ulcerated prepuce orifice becomes scabbed over and ultimately blocked - treament: - acidify urine by removing access to high protein diets or Ammunium Chloride TID |
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how would you categorise a ram affected with mange?
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"most often temporary unsoundness as the lesions disappear after treatment.
Severe infestations can result in permanent unsoundness if >50% scrotum affected - results in scrotal wall thickening which affects heat loss and is detrimental to spermatogenesis |
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what are the 3 methods of semen collection?
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"AV
Electro-ejaculator Collection from ewes vagina post service (morphology only) |
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What can semen be used for?
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"fertility indicator and culture for disease diagnosis
look at: semen density total volume (variable) wave motion morphology |
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what is the sperm quality?
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"normal sperm
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why is epididymitis always classified as permanently unsound?
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"infection causes inflammation of the seminiferous tubules in the epididymis resulting in obstruction and occlusion
the buildup of sperm results in rupture and spermatozoa flow out into the surrounding interstitial space sperm are haploid so are immunogenic resulting in a sperm granuloma sperm antibodies are produced further decreasing the viability of any semen produced |
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how is Brucella ovis diagnosed?
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"blood test (after 6 weeks)
- CFT and ELISA semen (after 3w) |
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how is Brucella vis treated?
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"palpate ALL rams
any with lesions isolate and CFT blood test cull all positives repeat palpations at monthly intervals once celar test wait 60 days and repeat palpation 2x clear tests 60d apart = Brucella ovis free flock |
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how is gram -ve epididymitis transmitted? what are the clinical signs? how is it diagnosed?
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"transmission:
- retrograde infection up the urethra into the accessory sex glands and epididymis from the environment clinical signs: - usually young rams - may become systemically ill - abscess may burst and thick pus drain outside - remnant epididymitis lesion, atrophied testis diagnosis: - can carry bacteria is sex glands for up to 2y - pus and inflammatory cells in semen samples - palpation and semen culture - BT no use |
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what are the factors that affect lambing percentage that we cannot influence? what impact do these factors have
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"- Weather and topography
- topography: can influence to a degree - choose where to mate ewes, lambing paddock, fertilisers - impact: - topography: ram tupping capacity, ewe feeding level via quantity and quality of pasture, neonate survival immediately post-birth |
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what (11) factors influencing lambing percentage can be altered by good management?
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"- Oestrus
- mature ewes stay in oestrus for 12-36hr - 2t 1-24hr - breeding season in ewes - ovulation rates - mating - fertilisation - embryo development and survival - foetal development and survival - birth - ewe survival rates - perinatal survival - growth of lamb |
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what effects do delaying the ewe joining mate have?
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"- high first cycle submission rate
- less ewes returning - shorter mating period - shorter lambing period - lambs born later = more grass for ewes = better lactation = faster lamb growth and survival rate HOWEVER advancing the mating date does NOT guarantee an advancement of mean lambing date due to lower ovulation rates earlier on (ewes are seasonal breeders) |
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why is the mating not delayed?
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"- premium lamb prices
- set lambing date that matches grass growth rate |
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what are the factors affecting the ewes breeding season?
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"- breed of sheep
- all short day breeders (Romneys < merinos) - latitude - closer to equator = sooner PSM - altitude - higher altitude = shorter breeding season - age of ewe - younger ewes are more difficult to get pregnant - ram effect - photoperiod control and melatonin - stress - eg shearing. should not be done 3 weeks before, during or after mating - hormonal induction of oestrus - CIDR/sponges (12-14d) - PMSG: injection. oestrus 24-72hr later |
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what impact does age have on ewe breeding season and why?
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"younger ewes are more difficult to get pregnant
(hoggets and maiden 2t) why: - cycle later - have shorter heats - have less cycles with lower ovulation rates - have lower conception rates - have higher EED rates |
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how can young ewes’ conception rate be increased?
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"- mate separately to main mob of ewes
- mate on easy rolling to flat paddocks so rams can find them - use more rams per 100 ewes - 1:50 - use experienced rams not young rams target hogged weight PSM = 39-42kg |
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write up a plan to synchronise ewe hoggets:
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"- ewes must not have contact with rams for at least 3w prior to PSM
- flush hoggets on good quality feed on a rising plane of diet >1250kgDM/ha (5cm) - Mate hoggets in small flat paddock so rams can find them - Put teasers out for 17 prior to PSM (tease hoggets for a long time = better response). - rams go out at day 17 at 1:50 ratio - hoggets should have 70% pregnancy rate post synchrony |
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what is the sequence of hormonal events occurring when between the teasers and rams being put out?
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"- within 10mins after teasers in: LH pulses. main pulse 27-36hr after.
- within 3d most ewes have silent ovulation (no ∆behaviour) - 60% of these ewes develop CL which maintains the cycle with a repeat ovulation occurring 18-20d after initial ram introduction - in 40% the CL regresses and at 6-8 days after ram introduction these ewes have a 2nd silent heat which is then maintained for a normal cycle length |
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what are the factors (11) affecting ovulation rates?
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"- bodyweight and nutrition level at mating
- aim: 55-60kg . draft out light ewes and priorities feed. - flushing 3w prior PSM >1250kgDM/ha - time of mating (early season vs Late) - ewe age - older ewes = more ovulations - genetics - finish landrace very fecund - Booroola gene : additive effect ( Merinos ) - Inverdale gene : very small increase. Rams —> daughters. ewes —> 50% offspring - homozygous = ovarian hypoplasia = infertile - diet : mating on lucerne and phyto-oestrogens in clovers - high OE —> inhibit LH —> inhibit ovulation - mycotoxins - reproductive depression - Pithomyces chartarum (FE) - liver damage —> low BCS —> low fertility - Zearalenone - level of feeding when younger - pre mating shearing - immunisation against ovarian steroids: Androvax - Androvax: immunisation against ovarian androgen Androstenedione (OE precursor) - 2x dose before PSM (8w, >4w prior) + annual booster >4w prior PSM - trace elements: Selenium |
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what effect does Oestrogen have on ovulation?
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"non breeding season:
- low level estradiol released from ovaries has negative feedback , inhibiting LH breeding season: - hypothalamus loses sensitivity to low dose OE, releases GnRH - stimulates pituitary to release LH and FSH - FSH stim’s follicles to mature - high OE —> LH surge —> ovulation oestradiol controls the number of follicles selected for ovulation |
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what factors affect fertilisation?
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"- length of mating
- ram harness + coloured crayon - detect mating patterns. aids in feed budgeting - embryonic mortality - fertilisation - 30d pregnant - >12d, affects cycle (CL doesn’t regress as fast) |
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what are the common causes of Abortion in NZ?
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"Camplyobacter fetus fetus
Toxoplasma gondii Salmonella brandenberg (South Island) |
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what part of gestation are Campy losses associated with?
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"ONLY associated with late gestation losses
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what is the epidemiology of Campy?
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"- introduced by carrier sheep to naive flock
- transmitted by - ingestion in feed or water - direct contact with aborted foetuses/membranes - scavengers eatting aborted foetuses - NO veneral transmission - can survive in envt for ~20d |
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what is the pathogenesis of Campy?
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"- bacteraemia
- bacteria invades and localises in the placenta and foetus - bacterial growth enhanced by placental blood supply and nutrients - placentitis: areas of necrosis in placenta and foetal tissues - foetal liver, lungs - Foetal death - infected ewes may become carriers - ewe post infection become immune |
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what are the clinical features of Campy infection?
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"- abortion storm
- last 6w pregnancy - may see ewes with blood on perineum or membranes protruding - most often in maiden ewes - ewes healthy (rarely metritis) - early neonatal loss - birth of weak lambs, reduced lamb viability - often outbreaks after ewes have been stressed - high stocking rate (high density winter grazing) - ewes remain immune for years afterwards |
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how would you diagnose Campy?
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"look at placenta:
- gross lesions - +/- oedematous, opaque placentae - +/- foteal liver lesions - foetus usually fresh - PM= microscopy of foetal stomach contents - culture |
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how do you control a campy outbreak?
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"- prevent/reduce exposure to infected pasture
- decrease stock density - shift u’s - remove/dispose of aborted material - quarantine affected cows - personal hygiene: fomites - antibiotics - not practical, but can be used - Streptomycin, penicillin, tetracycline - vaccinate for prevention, too late once broken out (3w prior. takes 10 days for effect) |
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how is toxoplasma gondii transmitted?
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"- reservoir: mice —> cats
- young cats shed > older cats - resistant oocytes contaminate hay , bedding , concentrate feeds where the faecal oral route occurs in the ewe - ram semen - Once infected immunity is lifelong so see abortions in completely naive flocks (rare) or mostly maiden ewes |
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what is the time from infection to abortion for T. gondii?
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"40 days
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what are the clinical signs of T. gondii?
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"EED (early embryonic death)
- resorption - late return to oestrus or increased Dry/Dry at end of scanning Mid-pregnancy (60-120d) - undeveloped foetal immune system - foetal death/ mummification/ abortion 120+ gestation - immune competency in lambs - born normal no systemic signs in ewes |
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how would you diagnose T. gondii?
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"- gross lesions +/- mummified foetus
- “strawberry cotyledons” - cotyledons with white/grey areas of necrosis - clear intercotyledon area - histopathology or cotyledons, foetal lungs, liver, brain - IFAT - sera from ewe: too late |
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how do you control T. gondii?
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"limit breeding cat population, especially litters in hay barns
vaccination: Toxovax - fragile - single dose to maiden ewes - ≥4w prior PSM |
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how is salmonella brandenburg transmitted
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"- introduced by:
- carrier sheep (up to 6m) - mechanical vectors: gulls - dust fomites - environmental survival ~ >4m - high stock density —> increased stress —> increased shedding of carriers - both MA ewes and 2t susceptible and often multiple bearing ewes |
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what are the clinical features of salmonella?
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"- abortion in late pregnancy
- foetus autolysed, smelly (dead>1d) - ewe often has difficulty expelling lambs - ewe sick. - necrotising metritis - ~50% aborting ewes die |
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how do you diagnose salmonella?
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"- location: south island
- history - clinical features - samples - culture of foetal stomach contents or liver, placenta, vaginal swabs - histopathology of placenta |
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how do you treat salmonella?
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"- guarded prognosis
- early and aggressive treatment of placentitis may prevent ewe death but not abortion - LA oxytetracycline - potentiated sulphonamides - NSAID - fluid therapy: not practical flock: - spread ewes out to decrease stocking rate and drop faecal/oral contamination - ensure plenty of clean, fresh water and adequate feed - avoid stressing ewes |
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how do you control salmonella?
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"vaccination “salvexin”
- incomplete protection, but pre-tup vax in face of outbreak recommended management: - avoid high stocking rate late pregnancy - minimise pre-lamb yarding and other stressors - purchasing - hygiene - disposal, quarantine, control gulls, personal/vehicle hygiene - Zoonotic |
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how is Hairy shaker disease/ Border disease transmitted?
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"via MM
introduced to flock by clinically normal sheep - persistently infected are source of infection |
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what are the clinical signs of hairy shaker/ border disease?
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"depends on when infection occurred:
- early gestation: - EED —> late return to oestrus, increased dry/dry at scanning - 60-120d: - mummies/abortion - +120d: - birth of hairy shakers - hairy, stunted lambs |
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how do you diagnose hairy shakers?
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"the presence of the lambs
- hairy, stunted, discoloured path of hair on back of neck ELISA |
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how do you control hairy shaker/border disease?
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"- avoid exposure of pregnant ewes to infection
- especially young naive ewes - mix new stock months before tupping ≥4w - cull affected lambs - call infected ewes who drop HS lambs |
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what are some other causes for abortion?
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"infectious:
- Bacillus spp - Fusobacterium spp - Brucella ovis (rare) - Listeria (silage) - Yersinia non-infectious: rare - high nitrate |
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in a PM on an aborted lamb, what samples should be taken?
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"take all samples as can have duel infections:
- foetal stomach contents - culture + microscopy - foetal liver/ lungs/ heart blood - culture/IFAT - foetal brain/ heart/ liver/ lungs - histology - placenta - fixed and fresh for culture and histology |
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what determines value of production animals:
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"how much output you can generate from a given set of inputs
inputs (costs) - feed/pasture - vet care - farm labour - housing/utilities Outputs (market value) - milk - meat - eggs - offspring - fibre - labour |
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your role as a farm consultant includes:
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"correcting problems
- developing treatment protocols identifying opportunities - reproduction, nutrition, management - improve herd performance preventing problems - vaccination, biosecurity |
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interventions that can be used to address health issues:
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"diagnostic tests
procedures mediactions vaccinations management culling decisions should be made that takes into account: - knowledge about disease - epidemiological consqeuences, available interventions, effects on production - knowledge about farm - cost of intervention, farmer objective, available resources - knowledge about externalities - animal welfare, environmental, and public health consequences |
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"“road map"""
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"- define the problem
- list alternative interventions - enumerate the costs and benefits - select a decision framework - decision tree analysis - partial budget analysis - cost-benefit analysis - choose course of action - monitor response |
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What are the main 3 species of concern regarding GIT parasites in cattle?
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"- Ostertagia ostertagi
- Trichostrongylus axei - Cooperia oncophora 2º importance - intestinal Trichostronglyus spp - other Ostertagia app - Oesophagostomum radiatum - Nematodirus |
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how quickly does immunity develop in cattle and sheep?
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"sheep:
- most disease in stock <18months - especially <12mnths development of immunity similar to sheep - apparent by 6mnths - starts to have impact - fully mature by 18mnths - still recognising parasite as foreign: will have protein losing enteropathy note: no PPR in cattle |
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describe the seasonal pattern of FEC and larvae in cattle:
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"- Winter/spring:
- larvae population declines - spring flush (grass growth) provides dilution factor - neglible FEC - Aug—> Nov - FEC increases before larvae - Oct—> Dec - conditions for larval development improves - increase population - calves reinfect calves - summer: - dry period limits FEC and larvae survival - dungpats: eggs survive more than in sheep pellets - peak larvae end of summer/spring - Autumn - conditions for good larval development: peak (partially winter) - immune response kicks in: FEC peaks and begins decline - Autumn/Winter - FEC dropped (immune response) - last wave of eggs develop into larvae - lag behind FEC in larval drop |
