Small Rum 1 Flashcards
(101 cards)
1
Q
In terms of reproductive performance in sheep flocks at what 7 stages do you measure
A
1) pre-joining
2) gestation
3) ferilisation
4) early gestation
5) later gestation
6) birth -0-3 days
7) lamb marking
2
Q
How do you measure reproductive performance on a farm during pre-joining, gestation and fertilisation and common issues
A
1) Pre-joining - Enter oestrus but not as much ovulation - fewer multiples
- One of the most important ones in sheep industry
2) Gestation - failure of insemination -> ram unable or unwilling to inseminate the ewe
- Now get increase in returns to service and fat rams (not as much activity)
3) Fertilisation - If ram the issue -> less maiden ewes (about 2 years old) pregnant
- Toxic problem and accumulative generally problem in older ewes (decrease pregnancy)
3
Q
How do you measure reproductive performance on farm during early gestation and what is important about this stage
A
pregnancy diagnosis in second trimester so will come up then
- Few pregnant and aborted foetuses (generally don’t find aborted foetuses)
PRENGNANCY SCANNING -> first time can check for losses from ovulation to early gestation
- Unsure on when reproductive failure has occurred
4
Q
How do you measure reproductive performance in late gestation, birth 0-3 days and lamb marking. which is most important
A
1) Later gestation - aborted foetuses are the clinical signs - again don’t see often
2) Birth + 0-3 days - due to perinatal ability of the mother (colostrum, weather etc), will see via dead newborns and low marking %
3) LAMB MARKING -> 1-2 weeks after lambing marking occurs - second time can check for reproductive failure
5
Q
What are the 4 main reasons ewes might be in anoestrus in pre-joining
A
- Haven’t reached puberty yet
- Too young
- Too lightweight - want them to be 75% of their adult standard weight - Have reached puberty but are currently low bodyweight/CS
- Wrong time of year
- Short-day breeders (extent varies with breed)
- Less seasonal breeds can be induced with ‘ram effect’ - Some toxins affect reproductive hormones & suppress oestrus
- e.g. coumestans from lucerne/white clover
6
Q
How to tell that ewes are in anoestrus at pre-joining and what influences anostreous if ewes old enough what is the main determinant of anoestrus
A
Anoestrus ewes show no mating activity
- Won’t be observed standing to be mated by rams
- Won’t be marked by rams wearing mating harnesses
If ewes are old enough, right and no toxins still depends on CONDITION SCORE
- Aim at condition score 3 mating and lambing
○ Increasing condition score = fewer dry ewes, more twins
- Short-term increased protein intake pre-mating (flushing) also increases conception rate
- 1 extra CS = extra 10-20% lambs born
7
Q
What are the 4 main reasons rams may not inseminate ewes
A
- Poor libido
○ Merino - high libido 1 ram per 100 ewes
○ Suffix - 2-3% - Balanoposthitis (‘knob rot’)
○ Treat symptomatically/ topically (antibiotics if severe) - Musculoskeletal problems discourage/prevent mounting
- ‘5 Ts’
– Teeth - need to be able to eat
– Torso - condition score 3.5 prior to mating -> will lose some weight
– Toes - not lame
– Tossle - penis and prepuce
Top 3 failure of insemination
– (Testes) - failure of conception (Fertilisation)
8
Q
What are the 2 reasons rams may mount ewes but not fertilise and how to prevent this
A
- Poor sperm output
- Not enough testis (size, no. rams) for ewes! - Poor semen quality
- Heat: fever, scrotal mange
- Orchitis e.g. brucellosis
Diagnosis, treatment, prevention:
- Use ‘1%+1’ fit, healthy rams
- Always use pre-mating Breeding Soundness Examination (5 Ts)
9
Q
What is a common disease cause of failed fertilisation in male, why does it lead to this, what lead to in females and transmission
A
Ovine Brucellosis (Brucella ovis)
- Mainly male infertility
○ Epididymis & testicular granulomas (shrink) after inflammation (swelling) -> asymmetry of testicle
○ Ewe abortions rare(?)
- Spreads male to male
○ ± mechanical transmission via served ewes -> 1 day to a week the bacteria can last in the vagina
Homosexual behaviour between rams -> transmission
10
Q
Ovine Brucellosis (Brucella ovis) how present and treat
A
- Lifelong infection, refractory to treatment
○ Acute phase - fertility 0% but chronic infection -> regains some fertility
§ Clinical presentation -> initially large decrease then years of suboptimal fertility in rams
○ Need to eradicate
○ Accreditation schemes exist
11
Q
Ovine Brucellosis (Brucella ovis) what are the 3 main options for eradicating and which recommended with pros and cons, also what diseases look like this and therefore should be tested for
A
- Cull all rams & replace from accredited flock
○ High changeover cost - OR test & slaughter - most common (described below)
○ Palpate & serology q 14- 21 d.
○ Two negative tests 30 & 90 days after last cull -> takes a while to seroconvert - Two flock system - not recommended
○ Keep existing rams
○ Buy new clean rams and keep separate
○ Slowly cull existing infected rams
§ Pros - not high changeover cost, may not be able to get all new rams in time for breeding season
§ Cons - need to keep them COMPLETELY SEPARATE -> high risk
Disease ○ Histophilus ovis, actinobacillus seminis, haemophilus somnus -> LOOK LIKE BRUCELLOSIS SO WORTH TESTING FOR IF ACCREDIATED BUT HAVING EPIDIDYMITIS
12
Q
Ovine Brucellosis (Brucella ovis) diagnosis and intervention timeline what are the 8 steps
A
- Suspect -> low/variable %, testicular abnormalities found during BSE
- Test rams - palpation, serology: some/all rams
- B. ovis positive
- Put rams in small groups - minimise the spread while get test and cull programme going
- Test and cull -> repeat for 2-3 weeks
- All negative test result
- Final ‘free’ test 1-3 months after all-clear
- Other considerations -> assess biosecurity, enter a state accreditation program (not for commercial flocks)
13
Q
What are some causes of failure of fertilisation of the ewe with return to service or without return to service
A
- With return to service
○ Something impairs sperm fertilising egg but doesn’t disrupt normal oestrus cycle
○ EG - oestrogenic clover, mating young ewes (ovulation not well timed with oestrus behaviour) - Without return to service
○ Ewes not pregnant but no longer cycle
○ EG - if mating period coincides with beginning or end of normal breeding season
§ OR oestrous may cease if ewes are under severe nutritional stress
○ Pregnancy loss after maternal recognition of pregnancy looks the same as this
14
Q
Oestrogenic clover what is the disease caused by, what occurs and clinical signs
A
Clover disease caused by phytoestrogens
- Impaired sperm transport or chronic uterine change
Clinical Signs
○ More older dry ewes - decrease fertility in older ewes
§ Accumulative effect -> longer exposure in older ewes so permanent infertility
○ Increased teat length, precocious lactation, enlarged genitalia in wethers & dry ewes
○ Vaginal, uterine prolapse (& ewe & lamb mortality)
15
Q
Oestrogenic clover disease diagnosis and treatment
A
Diagnosis ○ Identify clover ○ Wether teat length assay ○ Uterine histopathology -> cystic endometrial hyperplasia - not common Treatment ○ Avoid risk pastures near joining ○ Cull at younger age(?) ○ Graze cattle ○ Reduce stocking rate (to ↑ grass & ↓ clover) ○ Pasture renovation
16
Q
Embryonic or foetal loss clinical signs and causes d12
A
- Early embryonic loss looks like failed fertilisation with no return to service
- May miss abortus if in early pregnancy (<3 months)
- Ewes often OK
- May see prematurely born lambs if late abortion
d. 12
1. Selenium deficiency (NZ)
2. Onion grass poisoning - toxin fron fungus, can also cause neurological signs
3. Pestivirus
4. Listeria monocytogenes
5. Toxoplasma gondii
6. Campylobacter
17
Q
List the 3 main infectious causes of foetal loss and what do they all have in common
A
1) campylobacter
2) toxoplasma
3) listeria
- all zoonotic
- all oral
18
Q
Campylobacter how transmit, what occurs with infection, diagnosis and treatment
A
- when give birth shed organism and ewes that become exposed to environmental
○ If pregnant will abort and then will get lifelong immunity - ALSO - leads to target lesions on the liver
§ Main issue in maiden ewes with abortions -> just vaccinate these
○ If not pregnant then just get lifelong immunity - Culture - very hard to culture but SMEAR - will see the typical shape -> important diagnosis
- a/bs - antibiotics -> generally resistant to broad spectrum antibiotics -> HARD TO MANAGE OUTBREAK WITH THESE
19
Q
Toxoplasma how transmit, what occurs with infection, diagnosis, treatment and prevention
A
oral exposure to oocyst in cat faeces (generally younger cat)
- Protective immunity again important - so abortion depends on if pregnant when first exposed
○ Again main issue with maiden ewes -> so just vaccinate these (only in NZ)
- Foetal brain - good to find histology signs, maternal serology also important
- Treatment -> may not work as well if foetuses are already dying -> not 100% effective
- Prevention -> manage contact between ewes and cats -> exposure BEFORE PREGNANT
20
Q
Listeria transmission, what age occur, diagnosis, treatment and prevention
A
- ubiquitous in the environment -> delivery of infection through a source - predisposing factors are important
- Exposure doesn’t lead to immunity therefore can occur at ANY AGE GROUP
- Organs for histology, culture foetal brain membranes
- Treatment - antibiotics (penicillin or oxytetracycline)
- Prevention - manage feed sources and general ewe health
21
Q
Define pregnancy rate and conception rate, possible value, normal range, when measured and how to increase
A
Pregnancy rate
- No. ewes detected pregnant/ No. ewes mated x 100
- 0-100%
- >95%
Conception rate
- No. foetuses detected/
No. ewes mated x 100
- 0-200%+ (triplets)
- 95% (single lambing merinos) 150+% - fecund breed
- Measured at pregnancy scanning - later than bovine or equine
INCREASE - via nutrition (body condition score) at mating
22
Q
Define lambing rate and marking rate, possible value, normal range, when measure and how
A
Lambing rate - No lambs born/ No. ewe mated x 100 - 0-150+% - 95-150+% - Could be measured in the post-lambing period by regular counting of lambs, must include detection of dead lambs (hard to count)
23
Q
Define marking rate and weaning rate, possible value, normal range, when measure and how
A
Marking rate
- No. lambs marked/
No. ewes mated x 100
- 0-100+%
- 70 (merinos) - 150%
If <65% flock won’t breed enough to be self-replacing
- Count from lamb marking (2 weeks after end of lambing)
Large loss generally between lambing and marking - due to hypothermia, bad mothering etc.
Weaning rate
- No. lambs weaned/
No. ewes mated x 100
- 0-100+%
- 70-150%
- Usually little change from marking to weaning, except if outbreak of infectious disease eg tetanus
24
Q
What are the 4 ways to influence the oestrous cycle
A
1) melatonin
2) ovastim vaccination
3) PGF2 alpha
4) glucocorticoids
25
What does melatonin and ovastim vaccination do to the oestrus cycle, is it recommended and when use
1. Melatonin
○ Increase GnRH -> starts cycling and more follicles in the wrong season
○ Trade name: Regulin
2. Ovastim vaccination
○ Protein specific to negative feedback mechanism is in vaccination -> immune system destroys theses
○ Reduces androgen via -ve feedback -> more follicles -> increase amount of ovulation per cycle
○ Not recommended -> can improve the fertility but without increases nutrition -> results in increase undernourished and dead lambs
§ ONLY USE IF CONDITION SCORE IF PERFECT
§ Better in cross-breeds as generally larger lactation so can provide for the increase in number of lambs
26
PGF2alpha and glucocorticoids what do they do to the oestrous cycle and when use
3. PGF2alpha
○ Luteolytic (day 5-50/150 - end of first trimester or up to first half of pregnancy)
§ Regression on corpus luteum and at this point of cycle only source of progestagens so abortion
○ Goats -> don't have placental take over for production of progestagens so give PGF2alpha ANYTIME in cycle and will result in abortion
4. Glucocorticoids
○ Induce parturition in the last 10 days of pregnancy
§ Cattle: GCs work for longer time before normal calving
○ Only do to save the ewe under strict
27
What are some breed differences that help with breeding outside season
- ALL breeds naturally in oestrus in winter APRIL - JULY - GENERALLY MOST FARMS ARE HAPPY
- Merinos aren't as seasonal so higher percentage in oestrus during other months
○ Depth of anoestrus reflects how easy it is to induce cycling at these times
§ MERINO is the easiest
28
What are the 2 main techniques for getting merinos to breed all year round
1) exposure to males can induce oestrus
| 2) regulin - increases out of season cycling and ovulation rate
29
Exposure to males to induce oestrus what is needed from males, and how to perform - when come into oestrus and therefore when to mate and AI
- Males showing sexual behaviour and secreting pheromones
- Males and females needed to have been separated for >500m for 3-4 weeks
1. Most ewes ovulate after ram intro BUT NO OSTREUS (won't allow mating) - don't have progesterone primed brain
2. About half of the sheep CL regresses quickly and have normal cycle 17 days later - in oestrus
- Other half of sheep CL regresses normally and have normal cycle 19 days later - in oestrus
- THEREFORE -> 3 weeks after introduction of rams will see sheep in signs of oestrus
- Not good to synchronise animals -> 1 week spread of variation of ovulation THEREFORE GOOD ENOUGH FOR NATURAL MATING NOT GOOD ENOUGH FOR ARTICFICAL INSEMINATION
30
What are the 2 main types of teaser ram/bucks should you use with exposing ewes to males to induce oestrus and which shouldn't you use
a. Surgical vasectomy
§ Not fertile but still producing testosterone so still showing sexual behaviour
b. Testosterone-treated wethers
§ Long-acting testosterone and will induce male sexual behaviour
§ RESTRICTION ON THE USE -> only registered for use in AI programs or pizzle rot prevention
- Shouldn't use fertile rams because will then get a very long mating period -> BAD FOR MANAGEMENT
31
Regulin how given to the ewes, what does it do and what need to ensure
- Subcutaneous implant that slowly releases melatonin
- Stimulates out-of-season oestrus cycles
○ Premium prices for autumn lambs
○ Still works best in less seasonal breeds - merino
- Still must separate ewes and rams before
- Reduced ovulation rate afterwards if missed joining
32
Feed kgDM needed for late pregnancy grazing or triplets and at lambing CS
```
- Late pregnancy
○ Grazing 900-1000kgDM/ha FOO (-3cm+)
○ Triplets: 1100-1200kgDM/ha (4cm)
- At lambing
○ Ewe CS 3.2
○ Grazing > 1800kgDM/ha FOO (6cm)
```
33
Pregnancy diagnosis how done, what day, what looking for and cost
- Ultrasonography
- Day 50-100
○ Empty/single/twin -> looking for cotyledons
- Lay contractor: 50-80 cents/ewe
34
What are 6 important background influences on male reproduction
```
1. Age
○ Puberty, Sexual maturity
○ fertility - bell shaped curve -> generally 12 months of age
○ Senescence - old age
2. Season
○ Remember rams short day breeders!
3. Social interacting rearing
4. Environmental factors
○ Pastures - oestrogenic pastures
○ Pollutants - heavy metals and fracking
○ Predators
5. Nutrition
○ Bodyweight effects
6. Management factors
○ Time of joining, length of joining
○ Handling at mating
○ Male to female ratio
○ Factors around semen handling, storage and insemination in AI programs
```
35
what examining in a ram for scrotum and contents, what is important and what do you what the consistency of the testicles to be
- Scrotal skin
- Cords
- Symmetry
- Testicular size
- Testicular consistency
- Epididymis: head body and tail
Size of testicles
- Scrotal circumference
- Ranges Adult >32cms, lambs >30cm
Consistency of testicles - FIRM AND RESILIENT
36
what is a common what to collect semen, what useful for, discomfort levels
electroejaculation
- Rectal probe delivers electrical stimulus to nerves and tissues controlling ejaculation
- Useful/practical for collection in large numbers of rams (assess ram teams, pre-sale)
- Level of discomfort/pain comparable to that of handling alone
37
Examination of semen in field what are the important aspects and which stain used
- Volume.
- Concentration,
- Morphology
○ Small amount of abnormalities is normal
- Estimate “Wave motion”
-> RAPID SWIRLING WAVES - in low power
- MOTILITY= % moving actively forward
○ Want minimum of 30%
- Examination of semen in the laboratory - we now send it off
○ Sample for concentration:
§ Nigrosin eosin stained smear
□ Estimates % live sperm (no stain - dead sperm takes up the stain)
38
What are the 2 main congenital abnormalities that lead to reproductive disorder, uni or bilateral and what result in
1. Testicular hypoplasia - bilateral or unilateral
○ Smaller testes results in lower concertation of semen, lowered motility, not as firm or resilient
○ Could have normal head morphology or abnormal midpiece/tail morphology
2. Cryptorchidism - unilateral
○ Can still be fertile in the other testicle - difficult to tell by looking at the sperm
39
What is the main acquired abnomrlaities that is a reproductive disorder, result of infection and treatment
1. Scrotal mange - chorioptes bovis
○ Local increase in scrotal skin temperature resulting from inflammation
○ Exudative inflammation, thickening of scrotal skin, scaly, crumbly
○ Impairment of heat loss cause of testicular degeneration
○ Treatment: MLS - moxidectin, Ivermectin - repeated treatment
40
What are 2 reproductive disorders that can be acquired or congenital, causes, result from infection and types if applicable
1. Testicular degeneration
○ Acquired or congenital - thermoregulation failure to occur
§ Can be due to pyrexia or local inflammatory process, wool covered scrotum (reduces evaporative cooling)
○ Abnormal sperm and decreased scrotal circumference
○ Reduced fertility often infertile if severe
2. Spermatic granulomas
○ May result from acquired injury (nothing last year) or congenital defect (more likely in younger rams)
○ Any condition that causes leakage of spermatozoa or Spermatozoal antigens into the extratubular compartment is potentially complicated by this reaction
○ Spermatozoa incite - a granulomatous/pyogranulomatous response
○ Spermiostasis -> may result if granuloma blocks the efferent tubules in the ram
§ If bilateral -> will see semen but no sperm within
41
List the 3 main abnormalities in mesonephric derived structures
1) mesonephric duct development
2) seminal vasculities - bacterial
3) ovine brucellosis infection
42
Mesonephric duct development what species common in, what are the 2 abnormalities that can occur, clinical significance
Seminal vasculitis what leads to
○ Two disturbances in rams more common in bulls
a. Segmental aplasia - involving epididymides, vasa deferentia, ampullae and seminal vesicles
b. Fusion of pelvic mesonephric duct structures +/-aplasia
○ Variation in clinical significance
○ May be secondarily inflamed/infected
Seminal vasculitis - bacterial
○ Abscessation, fibrosis and inflammatory cells
Thickened septa, Leukocytes in lumen and epithelial cells mostly in tact
43
What are 7 important reasons to use artificial breeding
1. IMPROVE GENETIC MERIT of FLOCK
○ Spread proven ram over many ewes
○ Lower cost of genetic material esp. small studs
2. DISEASE CONTROL
○ No lice, footrot bacteria or drench resistant worms in semen
○ Lower risk for OJD, Brucellosis
3. STATUS SYMBOL
○ “The thing to Do”
○ ? Cost/benefit
○ Often used for less ewes than the ram could mate naturally
4. NEW BREEDS
○ Importing “new” breeds eg Texel, Ramboullet, Finn, Charollais, Isle de France etc. by embryo transfer
5. TRANSPORT
○ Easier to transport semen than rams
6. INSURANCE
○ Stored semen can be used even if ram dies
7. CENTRAL TEST EVALUATIONS
○ Only practical way to conduct large scale progeny tests and link these tests to others in other states
44
List the 5 steps in the semen collection and processing
1) check ram health - testes
2) collect semen - artifical vagina and elctro-ejaculator
3) examination and assessment
4) dilution
5) cooling and freezing
45
What are the 2 main ones of collecting semen, how works and which better
a. Artificial vagina
§ Training of rams needed
§ Individual ram variation
b. Electro-ejaculator
§ Vary pulse/frequency combinations for individuals rams
§ Generally poorer quality semen than AV (but much semen is now collected this way)
46
Describe the dilution process of semen processing and cooling and freezing - how done
4. Dilution
○ Tris or citrate buffer, glucose or fructose, egg yolk, UHT milk, cow's milk, commercial preps, etc.
○ Rate varies - quality of semen and purpose eg for laparoscopy - minimum of 20 million viable sperm in each ewe
5. Cooling and Freezing
○ Chilled semen
§ Cooled to 40C over 3-6 hrs, held at 50degrees C for max 24 hrs before use
○ Frozen semen
§ Pellets - diluted semen cooled then dropped onto dry ice then stored in liquid nitrogen
§ Straws – diluted semen sealed into straws, cooled then dunked in liquid nitrogen and stored
47
how to synchronise oestrus in ewes
- Progestogen containing vaginal implants
○ Inserted for 11-14 days
○ Oestrous occurs 48-56hours after removal
1. Sponges eg chronogest
2. CIDRs
§ Less vaginal mucus pooling, easier to use, preferred by producers, lower loss rate, slightly more expensive than sponges
48
List the 4 artifical breeding methods
1) synchronised mating
2) shot in the dark or cervical AI
3) laparoscopic artifical insemination
4) embryo transfer
49
Cervical AI pros and cons and how need to perform
○ Cheap but time consuming – usually done by owner
○ Detect cycling ewes – teaser ram with harness
○ Collect semen from ram and AI oestrous ewes daily
○ Frozen semen now used in Norway
50
Laparoscopic artificial insemination how is the semen given, what ewes used with and what needed to work
○ Frozen, chilled or fresh semen
○ Generally only used with synchronized ewes - only in Australia
○ Needs planning to get good results
§ Check nutrition of ewes
§ Availability of semen if being purchased
§ Staff availability on property to handle sheep
51
What are the 5 steps within laparoscopic artificial insemination
1) anaglesia - xyalzine - works in 10min and lasts 30min, cradle loading, cradle operating
2) skin preparation
§ Usual site - 10 cm anterior to teats on bare skin at the skin wool junction inside the flank on both sides
§ Clean puncture site with hibitane swab
3. Thawing frozen semen
§ Thaw semen in 370C water bath (20 -30 seconds)
§ Hold in 300C water bath
§ Check each batch for motility post thawing
4. Laparoscopy
§ Double puncture laparoscopy
§ CO2 used to provide working space
§ Semen injected into greater curvature of BOTH horns
5. Aftercare
§ Bleeders – suture
§ Wound treatment – Cetrigen or Alamycin aerosol - spray on
§ Minimal disturbance for first 2-3 weeks -> period of greatest embryo lost
§ Backup ram in at 14 days as never get 100% conception rate
52
With laparoscopy artificial insemination what are the 4 things that can go wrong
§ Perforate bladder – drain bladder – antibiotics?
§ Perforate rumen – release gas – antibiotics?
§ Inflate omentum – degas - reinsert trochar and cannula
§ Perforate vena cava …..
53
Embryo transfer what is the main issue and the 4 steps within
Selection of donor ewes - main problem with this
§ How? Most studs select on RAM performance -> ewe performance generally not much information on
1. Synchronisation and Superovulation
2. artifical insemination
3. embryo collection
4. embryo transfer
54
Describe the 4 steps of the embryo transfer
1. Synchronisation and Superovulation
§ Sponge/CIDR and then boost with PMSG/HCG/FSH
2. Artificial Insemination
§ Double AI - 48 & 56 hrs -> cover early and later oestrus ewes
3. Embryo Collection
§ 5-7 days post AI
1. Surgical – Laparotomy (scarring of fimbria etc)
2. Transcervical – Difficult to pass a catheter in sheep
3. Surgical transcervical – Better Collection
4. Embryo Transfer
§ Recipients synchronised to donors within 24 hrs
§ Embryo(s) inserted into uterine horn on same side as ovary with CL
55
What are the 3 main lice of sheep
1. Body louse: Bovicola (Damalinia) ovis
2. Foot louse: Linognathus pedalis
3. Face louse: Linognathus ovillus
56
Body lice how long, what feeds on, lives and lifecycle
- 2mm long, tan colour
- Surface feeder
- Lives only in woolly areas
35 day lifecycle
- Egg attached to wool fibre -> impervious to chemical treatment for 10 days until hatch
- Need to treat after 10 days again to kill these emerging nymphs
57
Body lice how host specific, how survives in environment, movement, whee found, transmission and survivial off sheep
- Host-specific – but has been shown to survive on goats
- Poor survival in the environment: sensitive to sunlight, water, temperature and humidity changes
○ Long fleece is a louse’s best friend!
○ Shearing greatly reduces numbers
- Limited movement except up and down the staple
- Population build-up tends to be faster after autumn shearing
- Lice are difficult find in short wool - JUST BECAUSE DON'T FIND DOESN'T MEAN LICE FREE
- Transmission requires direct contact: yarding, sheep camps, ewe / lamb
- Survival off-sheep is poor – but 3-week spell for shearing sheds suggested
○ Fences are no risk
- Essentially…louse problems always start with the introduction of lousy sheep
58
Body lice what are the 3 main clinical signs and differential diagnosis for these
1. Rubbing
2. Fleece derangement – cotting, tassels (pulled bits of wool), colour (more yellow), wool on fences
3. Losses of fleece weight (up to 1kg clean), discounts due to cotting and colour – can decrease fleece value by 20%
Differential diagnosis - IMPORTANT EXAMS - HOW WOULD YOU DIFFERENTIATE AND DIAGNOSE LICE
- Grass seeds: find seeds in affected sheep, typically autumn-shorn, examine pastures
- Itchmite: slower spread, prevalence low, generally older sheep in poorer condition – skin scrapings
- Dermo, fleece rot: not usually rubbing
- Photosensitisation
- Exotics: scrapie, sheep pox, Aujeszky’s disease
59
Body lice what are the steps in diagnosis and what does and doesn't constitute a lice diagnosis
- Yard one or more suspect mobs
- Select badly affected sheep
- May have to inspect several sheep
○ At least 10 sheep x 5 partings
○ Neck, shoulders and flank
○ Make partings in the wool in bright sunlight
○ Good vision is needed!
- One louse constitutes an infestation
- Failure to detect lice does not rule out an infestation
60
What is the important management decision for lice in short wool and long wool
- If lice in short wool -> shorn within the last 6 weeks - can eradicate
→ treat
- If lice in long wool - can only control
→ do nothing + treat at shearing, or
→ treat all or some of the mob now + treat at
§ shearing, or
→ shear early + treat at shearing - can be problematic
61
Competing treatment considerations with management of lice in wool
- Eradication is only possible in short wool (< 6 weeks)
- An unchecked infestation will reduce fleece weight and increase cotting
○ Also welfare issues if not treated
- Chemical and labour incur a cost when treating
- Short (prem) wool may incur a price penalty
- Shearers may not be available
- Pesticide residues may incur a price penalty
62
What are the 2 main treatment options and the 7 chemical groups
- Two broad treatment types:
a. Saturation (dipping and jetting)
b. Backliners/pour-ons
Seven chemical groups:
1. Insect growth regulators (IGRs)
2. Organophosphates (OPs)
3. Synthetic pyrethroids (SPs)
4. Magnesium fluorosilicate
5. Macrocyclic lactones (MLs)
6. Spinosyns (spinosad)
7. Neonicotins (imidacloprid, thiacloprid)
63
List the 9 factors affecting product choice for treatment of lice
1. Length of wool
2. Availability of water, plant, labour
3. Possible resistance (especially SPs but also IGRs) - hard to test for in sheep lice
4. Ability to re-muster after shearing
5. Management calendar esp time between treatment and lambing
6. Withholding periods (meat, milk)
7. quarantine periods
8. Flexibility in treatment time off-shears, e.g. up to 24 hours or up to 7 days
9. Other constraints e.g. Maverick® not on lambs <6 weeks old
64
What is important to consider with withhold period and quarantine period for lice treatment
- Withholding periods (meat, milk), wool harvesting interval, sheep rehandling interval (not allowed to be handled after being treated with certain chemicals for certain period of time, OP toxicity prevention) , export slaughter interval (ESI) - not on the label
- Quarantine periods: - not lambs or contact with any other sheep during this time
○ Triflumuron (Zapp®) 4 weeks - insect growth regulators -> still be infested for 4 weeks after treatment, takes this long to kill
65
Dipping treatment for lice what are the 2 types and how to prepare the dip
Types
1. Plunge dip
2. Shower dip
Dipping preparation
○ It is critical that the dip works properly and the chemical mixing is done correctly
○ Check:
§ Sump size for calculations
§ No arsenic - old dippers used arsenic which creates residues
§ Pump pressure is adequate (it usually isn’t)
§ Booms and nozzles of shower dip (pointed the right way, not blocked)
66
Dipping treatment for lice what need to consider when running the dip and important disease risks
○ Mix chemical well
○ Check first batch wet to skin level
○ Re-dip first two pens (shower) - swint from sheep skin hasn't been present to increase wetting or 30 sheep (plunge)
○ Don’t pack too tightly
○ Dunk each sheep twice (plunge)
○ Follow label on topping up etc
○ Don’t hold in draining pens - spread via certain parasites
Disease risk
1. Post-dipping lameness
2. Cheesy gland - caseous lymphadenitis
3. Malignant oedema
4. Dermatophilosis - wetting and proliferation of bacteria
5. Fleece rot - wetting and proliferative of bacteria
6. Hypothermia
7. Pregnancy toxaemia
67
Dipping treatment for lice what are the 5 considerations fr hygiene
1. Dip between 10 days and 4 weeks off-shears (shearing cuts have healed)
2. Use a disinfectant (e.g. Hibitane®)
3. Use zinc sulphate heptahydrate 1% - PREVENT DERMATOPHILOSIS (only thing)
4. Vaccinate with 6-in-1 - protect against cheesy gland and malignant oedema
5. Dip young sheep first
68
Pour-on for short wool (backliners) what are good princoples for backliners practice and eradication
○ Cleanly shorn sheep
○ Weigh sheep and dose to heaviest
○ Apply along midline from poll to rump
○ Avoid SPs (or IGRs) where resistance suspected
Principles of eradication - common to have to treat a few years in a row
- All sheep must be treated, including killers, rams, pets – and sucking lambs
- Sheep must be treated at the same time or strictly quarantined
○ Issue if shearing at different times
- Apply chemicals properly according to label directions – equipment must be in good working order
69
Backlines vs dips
- Quicker, less labour-intensive, less stress on sheep
- No water or plant needed
- No need for re-muster
- No waste wash to dispose of
- Fewer OHS concerns
- Sheep are marked - easy to tell which if any have been missed
- No dipping diseases
- …but not foolproof, questions over efficacy and more expensive
70
Long-wool lice treatment options what are the 2 main techniques and benefits/cons of each
1) Hand-jetting - saturation
○ Slow, arduous job but automatic jetting races, firefighters etc are not effective
○ Handpiece attached to pump unit
○ 0.5L fluid per month of wool
○ Should run around the body to the dripline
○ Check pressures
2) Spray-ons - back-liners
○ Easier and quicker than hand jetting but expensive and residues are a concern - can also be unpleasant to use
71
What are 4 principles for prevention of lice in sheep
- Inspect and quarantine all introductions (for footrot and other diseases as well) - for 1 year if possible
- Treat new sheep if suspect
- Stock-proof fences - biosecurity
- Routine inspections
72
Foot lice what called, what feed on, location and lifecycle
- Linognathus pedalis
- Larger than B. ovis, blue-grey colour
- Blood feeder (sucking louse)
- Inhabits hairy parts: lower legs, scrotum, belly, face
- Similar life cycle to B. ovis but 43 days
73
Foot lice how survives in environment, transmission, when populations peak and clinical signs
- Survives well in environment (18 days)
- Transmission by infested pastures, direct contact
- Populations peak late winter to early summer
- Burdens usually light and confined to one limb
- Heavier burdens may cause irritation with biting and stamping
74
Foot lice treatment
- Pour-ons not effective
- Most wet dips should be effective but none registered (cyhalothrin (Grenade®) was)
○ Need to dip twice 2-3 weeks apart as chemical not retained
- Closantel and macrocyclic lactone drenches (ivermectin, moxidectin) probably effective
- Move to clean paddock after treatment
75
Face lice what called, size, lifecyce, transmission, location and treatment
- Linognathus ovillus
- Larger than B. ovis or L. pedalis
- Life cycle assumed to be the same as other species
- Transmission thought to be by direct contact – poor survival offhost (4 days)
- Wool /hair junction on face – heavy burdens cause irritation
- Treatment as for L. pedalis
76
What are the 3 mites of sheep
1. Itchmite: Psorobia ovis
2. Chorioptic (scrotal) mange: Chorioptes bovis
3. Sheep scab: Psoroptes ovis
77
Itchmite what called, lifecycle, location, sensitive to, peak population, transmission
- Psorobia (formerly Psorergates) ovis
Lifecycle
- 5-6 week life cycle entirely on the sheep
- Eggs laid on skin surface, hatch after 11 days
- 3 larval stages in stratum corneum
- Adults on surface of skin
Epidemiology
- Flock prevalence is unknown
- Found on shoulders, flanks, back
- Sensitive to high temperatures and desiccation but not rainfall
- Peak population in late winter / spring
- Transmission is best off-shears, ewe-lamb
- Spread is slow
78
Itchmite what are the 3 main clinical signs, how common, which sheep most affected and economic impact
1. Biting and chewing due to hypersensitivity
2. Pulled wool, cotting on flanks and thighs
3. Excess scurf
- Rare for more than 5-10% of flock to be affected
- Poor and older sheep most affected - DIFFERENT WITH LICE (affect all equally)
- No correlation between burden and severity of signs
- Economic impact minimal
79
Ithcmite diagnosis and treatment
Diagnosis
- Differential diagnosis lice, grass seeds, tender wool
- Flock picture is different to lice: plateau of spread (older), small number affected
- Scrapings from midside flank to confirm
Treatment
- ML drenches (ivermectin, moxidectin)
- Dip with a product containing amitraz or rotenone – not worth doing unless also dipping for lice
80
Chorioptic (scrotal) mange what called, lifecycle, location, transmission and 5 main clinical signs
- Chorioptes bovis
- Similar life cycle to itchmite but shorter (3 weeks)
- Affects lower legs, scrotum, udder, poll
- Transmission by direct contact (joining, suckling) and pick up from pasture
Clinical signs
1. Pustules, yellowish crusts
2. Skin thickening
3. Irritation leading to rubbing and biting
4. May affect fertility (look for mange as part of pre-joining exam) - IMPORTANT ECONOMIC AFFECT
5. Unusual gait
81
Chorioptic (scrotal) mange diagnosis and treatment
- Confirm diagnosis with scraping
Treatment
- Not usually justified unless affecting scrotum
- OP dipping / jetting will control
- Ivermectin / abamectin (cattle) 1-1.5ml/50kg injectable, 2 doses 10 days apart - RECOMMENDED TREATMENT
- Oral ML drenches will also control
- None of these are registered – moxidectin (Cydectin® registered?)
82
Sheep scab what is it, is it present, lifecycle, species affected, location, environment it likes and transmission
- Psoroptes ovis
- Exotic to Australia and New Zealand
- Related to itchmite (Psorobia) but with much more damaging mouthparts
- Life cycle similar to Psorobia but 11-12 days
- Affects sheep, cattle, horses, goats
- Lives all over the body especially infra-orbital, perineal, inguinal, scrotal and interdigital areas
- Favours a cool moist environment and will survive up to 3 weeks off the sheep
- Transmission via direct contact, via the environment (e.g. sheep camps), via mechanical vectors (e.g. birds)
83
Sheep scab clinical signs and diagnosis
Clinical signs
- Similar to chorioptic mange but more severe
- Mites puncture epidermis and feed on lymph
- Papules / pustules with yellow exudate, leading to large scabs
- Irritation leading to rubbing and biting, bleeding, more scabs
- Fleece damage and shedding -> looks like flystrike
- Sheep may lose condition and die
Diagnosis
- Differential includes lice, ked, itchmite, other mites, flystrike, grass seeds, dermo, fleece rot, tender wool, scrapie, Aujeszky’s disease
- Scrapings to confirm
84
Sheep scab treatment/ how eradicated and principles need to use
- Can be eradicated by:
○ Dipping with OPs (diazinon=dimpylate)
○ Injectable moxidectin / doramectin / ivermectin – moxidectin preferred because it persists beyond 17 days
- Principles similar to those of lice control in Australia, with added problem of environmental survival
○ Treat everything at the same time
○ Spell paddocks, buildings, yards for 17 days
○ Stop strays
○ Follow label directions carefully
85
Ked what is its name, what feed on, how common, what climates, location, transmission and what sheep mostly affect
- Melophagus ovinus, a wingless fly
- Blood-sucking
- Very rare if not eradicated
- Cool, wet climates - Gippsland
- Poor environmental survival (few days)
- Shearing time determines population curve
- Persist in protected areas like neck folds after shearing
- Transmission by direct contact
- Numbers highest in young sheep
86
Ked clinical signs, diagnosis and treatment
1. Fleece derangement due to irritation
2. Anaemia, ill-thrift
Diagnosis - Look for keds, pupal cases, faeces, musty odour of wool especially in neck, shoulder, belly and crutch wool
Treatment is never an issue – susceptible to OPs, SPs, rotenone, ivermectin
87
Blow flies list some primary and secondary strike flies
1. Primary strike flies: initiate strikes – Lucilia cuprina by far the most important, several Calliphora spp. (brown blowflies) cause 5-10% of primary strikes
2. Secondary strike flies: attack strikes initiated by other flies – Calliphora spp. and Chrysomya rufifacies (hairy maggot blowfly)
88
Blowflies lifecycle, what required to begin
- Protein meal required before laying
- Clusters of 50-250 eggs, 12-36 hours to hatch
- 3 larval instars feed on the sheep for 3-4 days
- Pupate in soil, emerge as adults
- Minimum time for life cycle is 2-3 weeks
- In winter, many pupae die, others ‘over-winter’, emerge in spring as a fly-wave
- Covert strikes multiply the population
89
Blowflies when need to breed, when sheep are susceptible, what rainfall needed, what prediposes, where live
- Flystrike requires flies and susceptible sheep
- Flies breed when temps >17oC and <38oC and wind speed <30km/hr, i.e. usually late spring – autumn
- Sheep are susceptible due to moisture: from excreta, exudate, rain, dip
- Often medium-strong wool sheep in high rainfall areas
- Dermo, fleece rot predispose for flystrike
○ Fleece rot precursor for body strike (moisture and protein)
- Long wool in the fly season increases risk
- Flies generally live within a 2km radius
- Brown blowflies cope well with the cold and are the first to emerge in spring
90
Blowfly strike what are the 7 locations and clinical signs with different types
```
Location of strike
1. Body
2. Breech
3. Pizzle
4. Poll
5. Foot
6. Udder
7. Wound
Clinical signs
1. Moisture, discolouration, bad odour
2. Twitching, irritation, stamping
3. May result in sepsis and death
4. Wool break in surviving sheep
- Overt vs covert
○ Covert generally early in the season -> harder to see the clinical signs
○ Overt -> more obvious clinical signs
- Severity and progression vary
```
91
Blowfly strike what are the principles to treat the sheep and what if repeatedly struck
- Treatment should be carried out as soon as possible to reduce suffering and avoid death, and to reduce buildup of fly numbers
- Clip the area thoroughly – very important – at least 5cm margin
- Collect maggoty wool in a plastic bag and leave in the sun to kill maggots
- Apply a chemical dressing
- Remove to a hospital paddock
- Cull ewes that are repeatedly struck - GENETIC PREDISPOSITION
92
Blowflies what are the 2 purposes for chemical treatment of struck sheep and the registered chemicals
1. Kill remaining maggots
2. Prevent re-strike as area is drying and healing
- Registered dressings are either:
○ OPs (diazinon, propetamphos, chlorfenvinphos) – but resistance
○ IGRs (cyromazine) – does not kill maggots
○ MLs (ivermectin), or
○ Spinosyns (spinosad)
- Effective wound clipping is probably more important than choice of chemical
93
What are the 2 main ways to prevent blowfly strike and things within
1. Blowfly prevention relies on reducing the number of flies -> harder to do
1. Flytraps – no longer available as not really effective
2. Early jetting - before the expected build-up of flies, e.g. September rather than November) can reduce or prevent waves – similar to summer drench theory
2. Making sheep less susceptible
1. Surgical modification -> tail docking, mulesing, crutching, treat for nematodes (decrease scours)
2. Husbandry
3. Breeding
4. Chemical
94
Surgical modification to prevent blowfly strike what are the 4 things can do
1) tail docking
2) mulesing
3) clips
4) pizzle dropping
95
tail docking what used for, what does it do and how to perform
Surgical modification to prevent blowfly strike
○ Tail docking has a huge impact on the incidence of breech flystrike
○ Tails should be docked at the third palpable joint, just covering the vulva of ewes and equivalent in males
96
Mulesing what used for, what regulations surround it and what should use
Surgical modification to prevent blowfly strike
○ Mulesing has a huge impact on the incidence of flystrike, but is a major welfare concern in its own right
○ The Animal Welfare Standards and Guidelines for Sheep stipulate that:
§ Sheep may not be mulesed less than 24 hours old or more than 12 months old
§ Sheep that are 6-12 months old may only be mulesed using appropriate pain relief
○ Tri-Solfen®
§ Topical spray -> aftercare
§ Combination local anaesthetic / vasoconstrictor / disinfectant
§ Requires vet prescription
§ 50-60c/dose
97
Clips what used for, how apply, what occurs, how effective
Surgical modification to prevent blowfly strike
○ Four clips required for each lamb
§ Two breech clips
§ Two tail clips (different style)
○ Avascular necrosis of the skin, falls off leading to hairless/smooth breech
○ Must be applied by an accredited contractor NOT FARMER
○ Clips are removed after 8-14 days and can be re-used at least once
○ Not as effective as mulesing, but some effect
98
PIzzle dropping what is it and how to perform
Surgical modification to prevent blowfly strike
○ Not permitted anymore
○ Cut the sheath that holds the pizzle (prevent urination into own wool as now hangs down)
99
What are 5 husbandry procedures to prevent blowfly strike
1. Time of shearing – spring vs autumn - spring reduce susceptibility to flystrike
2. Crutching – late autumn for spring shearers, spring/summer for autumn shearers
3. Ringing – remove wool around prepuce
4. Worm control
5. Controlling footrot / abscess
100
Breeding to prevent blowfly strike what is involved and focus on
○ Run an appropriate strain (e.g. finer wool types in high rainfall country)
○ Select against fleece rot (body strike)
○ Focus now on breech traits to manage flystrike:
§ Breech wrinkle
§ Size of bare area
§ Dag
101
Chemical prevention for blowfly strike when can't you treat, what are the main technqiues and chemicals used
○ Same basic groups as for lice but with some important differences (no magnesium fluorosilicate, some IGRs not for flies)
○ Eradication is not an option
○ No critical short / long wool distinction as with lice
○ As for lice, two broad treatment types: saturation (jetting) and backliners
○ Fly control from dipping or short-wool backlining is usually a bonus rather than a primary objective – fly control is not as important in short wool - unlike lice where need to treat all
Dicylanil -> most commonly used due to large window of protection
