Small ruminant Flashcards
For self-replacing flocks, there is a critical lambing percentage below which the flock does not generate sufficient replacement lambs to sustain the flock. What is it?
60-65%
What are some major factors affecting ewe oestrus?
- age (puberty at 165-483d)
- season
- body wgt
- nutrition/ management
- coumestan
What is the ovulation rate?
= # follicles ovulated by ewe in a cycle
What is current recommended BCS for ewes and rams at joining?
Ewes: 3
Rams: 3.5-4
What is Knob rot? How is it spread? Does it affect ewes?
Balanoposthitis (due to herpesvirus or mycoplasmas? Not really understood)
Between rams at joining (after mating a ewe that has recently be joined with an infected ram)
Ewes can get vulvitis/ vaginitis from it
What is an ideal scrotal size in a ram BSE?
<31cm
What is brucellosis? How is it spread?
How might you manage it?
- Testicular disease caused by brucella ovis-> granulomatous epipidymitis -> restricted sperm output and testicular atrophy
- Mating recently joined ewes and homosexual activity
- Sell or slaughter and replace; two flock system, test and slaughter
What is clover disease? What are the two types of disease it causes?
Failure of fertilization of female ewes with increased returns to service. Observed in sheep grazing pastures with high concentrations of plant isoflavone compounds which have oestrogenic activity.
- Temp clover disease: temp infertility. mucus in crevix and uterus become more fluid and impede sperm movement
- Perm clover disease: cystic glandular hyperplasia/ mucus change
What are some strategies to consider when dealing with clover disease?
Graze cattle instead
graze wethers instead of breeding ewes
reduce age of breeding flock (this has implications for fecundity though)
reduce stocking rate
avoid exposing ewes at joining time
pasture renovation/ improve soil fertility
What are the four most common causes of abortion outbreaks in ewes in southern Aust?
- onion grass poisoning
- campylobacter (fetus ssp fetus and jejuni)= vibriosis
- toxoplasma gondii
- listeriosis
How do ewes get campylobacter and what does it cause? Can it be treated/ managed?
Oral infection. Causes abortion in mid-late preg (>3months). Target lesions on liver.
Yes. Can try a/b (oxytetracycline). Also subdivide into smaller groups to minimise spread. There are also vaccines which cause long lasting immunity
What does toxoplasma gondii cause in pregnant ewes? How can it be managed?
If infected early, causes foetal death, resorption/ mummification
If infected later in gestation, possibly abortion or weak full term lambs or immune healthy lambs. Most commonly abortion in mid-late preg
- expose non-pregnant ewes to get long-lasting immunity
- coccidiostats in feed for susceptible ewes
- manage cat pop (keep the oldies around)
How might you manage listeriosis in breeding ewes?
Avoid grazing of severely water affected pastures, rotting vegetation
When is a BSE of a ram usually conducted with relation to breeding?
1 month prior
What is sperm motility?
Percentage of sperm actively moving forward
Rams fed on high protein diets are at risk of what in terms of reproductive abilities?
Ulceration caused by C. renale
What two bacteria are most often responsible for swelling/ inflammation of the scrotum?
Br.ovis and A. seminis
What breed of rams appear to be more resistant to infection with Brucella ovis?
Merino (cff. British breeds)
How might rams be infected with Br. ovis?
- Serving ewe at the same heat period as another infected ram
- Homosexual activity between rams
What is the incubation period of brucellosis?
8-12 weeks
How might brucellosis be controlled or eradicated from a flock?
Serological testing
Clinical examination +/- semen exam
hygiene
- in infected flocks, separate younger rams and mate them first. Make sure all rams entering flock are tested and are serologically negative
Hypoplastic testes may be due to what??
- Disturbances of descent
- An abnormal sex chromosome constitution
- Hormonal imbalance in the embryo
- Segmental aplasia of the mesonephric duct
- Chromosomal translocations causing misshapen testicles
- Inguinal hernia
- Poor nutrition and parasitism during dvpt.
What are two of the most common causes of testicular degeneration in rams?
Overheating and reduced efficiency of testicular cooling
arsenic poisoning and Vit A def also
At what age do sheep and goats reach puberty? What is the length of their respective oestrus cycles?
Sheep: 165-483d, 17d
Goats: 90-240d, 21d
How does oestrus activity get influenced by day length in seasonal breeders?
Increasing darkness ->increased melatnin from pineal gland -> increased GnRH from hyp ->increased FSH from ant pit
What is Ovastin?
Synthesized compounds used to increase number of twins and triplets. It induces antibodies to prevent negative feedback loop on hypothalamus
How do you administer Ovastin?
Need 2 initial doses 2 months and 1month pre-joining and a 12 monthly booster
What is regulin?
slow-release SC melatonin to bring seasonal breeds into oestrus
What are prostaglandins used for in small ruminants?
To return to oestrus (2-3 d later) Preg termination (used off label). Up to day 50 in sheep, and for entire pregnancy in goats (bc no placental prog)
What percentage of body weight should ewes reach by first breeding?
Merinos- 75%
Sheep meat breeds- 65%
Lamb neonatal mortality can be very high in pasture based systems. What are approximate percentages for singles and twins?
What is the most common cause of such deaths?
Singles: 10-20%
Twins: 20-30%
Starvation/ exposure / mismothering complex
Is seasonality in goats more pronounced at higher or lower altitudes?
Higher latitudes
What is the Ram/Buck effect?
Introduction of sexually active males to females after complete segregation to induce ovulation within 2-10 days.
Note: there is no oestrus with these early ovulations because the brain hasn’t been progesterone primed. Oestrus from male effect seen 19-23 days later
What is the ideal joining weight of an alpaca?
Should aim for 65% of mature body weight
~45kg at 1 year -> 70kg mature body weight
Describe the basics of follicular waves in alpacas and why this is of significance (3 main points).
- Follicular wave growth involves synchronous emergence of several follicles (waves every 12-22d)
- Consecutive follicular waves do not necessarily alternate between ovaries.
- A follicular wave emerges as soon as the dominant follicle starts to regress. Therefore, both regressing and emerging dominant follicles can be seen on the ovaries at the same time -> there is a DF considered capable of ovulation in either ovary most of the time -> repeated US need to establish phase of growth
What size does an alpaca ovary need to be to be considered cystic?
Over 12mm (7-12mm is the “sweet spot”)
Behavioural oestrus in alpacas is dependent on what?
Lack of progesterone (rather than presence of oestrogen)
What are some methods of pregnancy testing in alpacas?
- spit off test (reject male by spitting if they have a CL and elevated prog)
- elevated blood/milk prog (greater than 2ng/ml)
- transrectal/transabdominal US (foetal heartbeat form 25d)
- manual rectal palpation (35d onwards)
- transabdominal ballottement (8mo onwards)
What are the stages of gestation in an alpaca?
Stage 1: 1.5-2 hours
Stage 2: delivery of foetus (takes 30-45 mins, dam remains standing)
Stage 3: delivery of foetal membranes (1-4 hours)
***cria usually sits up in 10 mins
What is the interval from parturition to the resumption of ovarian follicular activity?
Usually 5-7 days (may be ready to ovulate by 10d post partum)
What is footrot in sheep?
A contagious disease caused by Dichelobacter nodosus. Requires warm, wet conditions and cannot survive for more than 7 days off a sheep. All strains infect sheep.
How do strains of footrot affect goats cf sheep?
Both species are affected by all strains, however in goats, benign starins look virulent, and virulent strains look benign.
What are some reqs for footrot to spread?
Interdigital skin must be disrupted. It must be wet and have an average daily temp of >10 degrees
Why is footrot so costly?
Decreases wool production and feeding, decreased stock sales and higher health costs all contribute to high cost.
How is footrot diagnosed?
Based on clinical expression. Smears are of no real value. Other lab tests are available including Gelatin gel test, elastase test, Int A or PCR
What factors affect the clinical expression of footrot in sheep
- Environment (moisture and temp)
- Virulence (several strains)
- Type of sheep
- SR
- Control strategies adopted (footbathing, vacc)
- Pasture quality (species, fertility, length of growing season)
What score lesions would you expect with benign footrot?
1-3a
intermediate score 2-4, virulent score 3-4
Can footrot be eradicated?
Virulent footrot can, and it is is cost -effective to do so. Opposite is true for benign footrot
What is footrot weather and when should it be controlled with regards to this?
Spread period is mostly Spring? Autumn (warm, moist weather). This is when it should be controlled. The non-spread period is usually Summer when it is hot and dry. this is the time to eradicate
What are some control options for footrot?
- Footbathing (8m +)
- Vaccination (virulent strains)- not that useful because of the antigenic variation
- Do nothing
What are footbath solutions options for footrot control? When should they be stopped?
Walk through: -Formalin (makes feet hard) -10% zinc sulphate weekly Stand in (15 mins every 2 weeks): -10-20% zinc sulphate -Footrite -Radicate
Should be stopped a month before inspections bc they can mask lesions
What is the problem with the newly registered vacc for footrot in sheep?
Restricted release. High efficacy but very costly if more than 1-2 serogroups (majority of places have more than 2 serogroups)
What bacteria in normally involved in foot/heel abscesses? What are some risk factors for this occurring?
Fusobacterium necrophorum, Arcanobacter pyogenes
Wet, muddy condition, heavy pregnant ewes/ rams, breed (merino, crossbreeds), older sheep.
What are the relative prevalences of toe and foot abscesses in sheep?
Toe: rarely more than 5%
Foot: Usually less than 5%
What is scabby mouth? How might it be managed?
=zoonotic disease caused by Orf virus. Occurs in lush condition in young sheep and lambs. Vacc is available but not always used. Causes mouth and foot lesions
What is strawberry footrot?
Dermatophilosis congolensis. Same bacterium that causes lumpy wool. Occurs in extremely wet humid conditions
What causes laminitis/ founder in sheep?
Introduction of grain feeding
What bacteria may be involved with arthritis in sheep? How would you treat?
Chlamydia (oxytet), Erysipelothrix rhusiopathiae (penicillin)
If purulent arthritis may also be caused by A. pyogenes, F. necrophorum, staph, trep, H. ovis
What is caprine arthritis encephalitis virus?
Notifiable disease in goats caused by a lentivirus. Cause arthritis, hard udder, chronic interstitial pneumonia, chronic weight loss and leukoencephalomyelitis
How is caprine arthritis encephalitis virus diagnosed and controlled?
Dx: Css,, hitopath, serology
Cx: Prevent transmission (snatch rearing), ongoing testing and culling
When does sexual activity begin in camels? What weight do they need to obtain to have a good chance of conception?
2-3 years of age
60-66% of their mature weight
In alpacas, the ovary is approximately what size?
The size of a peanut!
1 x 1 x 1.5cm
How often do camelids exhibit new waves of ovarian follicular growth?
Every 12-20 days
What is an important consideration with camelid follicular dynamics with regards to mating management?
Follicular waves emerge as soon as dominant follicles start to regress and don’t necessarily alternate between ovaries. This means that repeated ultrasonography is needed in order to establish whether a relatively large follicle is in the growing, static or regressing phase.
In camelids, behavioural oestrus is associated with what hormonal profile?
Lack of progesterone rather than a presence of oestrogen
In terms of the sizing of the camelid reproductive tract, what is important to remember?
Their vagina is 15-20cm long so a long narrow speculum is needed (SA speculum won’t suffice)
What are the 3 main stages of camelid reproduction?
- The unmated non-ovulatory female
- The mated, ovulatory but non pregnant female (mated but failed to conceive)
- The pregnant female (mated, ovulated and pregnant)
Describe the first stage of camelid reproduction.
=the unmated non-ovulatory female
- induced ovulators, non-seasonal follicle activity
- ovarian follicle waves occur q. 12-22 days, waves overlap by 1-4 days
- plasma oestradiol peaks 8 days after new wave emergence
- ideal mating time is in late growing/ early mature phases of growth (~10d)
- females are receptive most of the time with intermittent periods of non-receptivity lasting 1-2 days as new wave develops (long periods of receptivity regardless of follicle size)
Describe the second stage of camelid reproduction.
=the mated, ovulatory but non-pregnant female
- a mating that occurs in the absence of an ovulatable-size follicle (7-12mm) will not induce ovulation and conception will not occur
- an LH surge occurs 30-60mins after mating in response to an ovulation inducing factor
- 10-25% of females with an ovulatable-size follicle fail to ovulate
- 3 days post mating (2 days post ovulation) a CL develops
- when conception fails, prostaglandin is released from uterus and luteolysis occurs 9-11d after mating
- females are receptive again 12-14 days after mating if conception fails
What behavioural and physiological signs will be present in a female camelid when a CL is present on her ovary?
Circulating plasma progesterone levels are greater than 2ng/ml
When placed in a pen with a macho, she will strongly reject the male by spitting, kicking, squealing and running away.
How frequently do multiple ovulations in camelids occur?
In up to 10% of natural matings
How long after mating, is the egg released in camelids?
How long after unpacking does ovarian activity resume?
26 hours post coitus
5-7 days post unpacking
How common in cryptorchidism in alpacas?
Not really a thing because the testes are present in the scrotum from birth
How are the testes positioned in alpacas? What type of penis do they have?
Cranioventral/ craniodorsal axis
Fibroelastic penis with a pre-scrotal sigmoid flexure (note: penis cannot be normally exteriorised)
From what age to male camelids exhibit mating behaviour? From what age does testosterone production occur? By what age should all males be fertile?
Mating behaviour from 1 month old.
Testosterone production from 12 months old
Fertile by 3yo
What are the accessory sex glands present in the male alpaca/ camelid?
2x bulbourethral glands
1x prostate gland (dorsolat to urethra)
NO seminal vesicles
What is the max number of matings a male camelid is capable of per day?
2 (small testes!!! Low sperm numbers)
How does copulation occur in camelids?
Sitting position
Intracornual deposition of semen
Multiple ejaculations over 15-20 minutes
Only ~1ml semen delivered
Approximately what percentage of matings result in conception in camelids?
50%
Describe the third stage of the reproduction cycle in camelids?
Hatched blastocyst enters uterus 6-7d after mating. Implantation day 18-20
8-10d for MRP
CL required throughout pregnancy.
98% of pregnancies in LEFT uterine horn
What is the average gestation length of an alpaca?
342d (range 300-380d)
*Longer in Spring, shorter in Autumn. Warn owners that date could vary +/- 6 weeks
What type of placenta does a female alpaca have?
Epitheliochorial, diffuse placentation
In what ways can pregnancy be diagnosed in an alpaca?
Indirectly: sexual behaviour, blood/ milk progesterone levels.
Directly: US (foetal heartbeat at d25), manual rectal palpation (35d) and transabdominal ballottement (8m)
How long do each of the stages of parturition take in alpacas?
Stage I: 1.5-4 hours
Stage II: 30-45 mins
Stage III: 1-4 hours, RFM >6h
- most births occur between 7am and 2pm and they do not often show signs of impending delivery
- *uterine involution takes 20d
What are 5 breeding recommendations for alpaca breeding?
- Males should be mated at 12+ months old if reached 65% of mature bodyweight
- Spit-off at 7 days to check for ovulation
- Spit-off at 14 d to check for preg
- Spit-off regularly until US preg test (at 30 and 60d)
- Spit-off intermittently throughout gestation
What is the recommended joining ratio for alpacas?
What days will most matings occur?
3-4% (1:25-33)
Days 0-4, 12-16, 24-28
What are some reasons for wanting to uses AI in small ruminant reproduction?
- Improve genetic merit of flock
- Disease control
- Status symbol
- New breeds
- Ease of transport
- Insurance
- Central test evaluations
Can an electro-ejaculator be used in rams?
Yes but it generally produces poorer quality semen
What factors need to be assessed in semen collection and processing?
Colour, volume, wave motion, motility
Dilution (tris or citrate buffer, glucose/ fructose, egg yolk etc)
What is the difference between pelleted frozen semen and straws?
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
What are some methods for oestrus synchronisation in ewes?
- Progestagen containing vaginal implants (inserted for 11-14d. Oestrus occurs 48-56 hours after removal)
- Sponges (eg. CHronogest)
- CIDRs
What are some methods for follicle stimulation in ewes?
PMSG
hCG and FSH (for super ovulation)
What are some artificial breeding methods used in sheep?
- Synchronized mating
- Shot in the dark or cervical AI
- Laparoscopic AI (in synched ewes)
Where is semen placed in laparoscopic AI in sheep? What things may go wrong with this procedure?
Greater curvature of both uterine horns
- Perforation of bladder, rumen or even vena cava
- Inflation of omentum
What are the principles of embryo transfer in ewes?
- Selection of donor ewes- mostly selected on ram performance
- Synch and superov- sponge/ CIDR, PMSG,hCG/FSH
- AI- at 48 and 56 hours
- Embryo collection at 5-7d post AI
- Embryo transfer- recipients synched to donors within 24 hours. Embryos inserted into uterine horn on same side as ovary with CL
What factors affect product choice when treating body lice in sheep?
- Length of wool
- Availability of water, plant, labour
- Possible resistance
- Ability to re-muster after shearing
- Management calendar
- WHPs
- Quarantine periods
- Flexibility in tx time off-shears
- Other
What are some classes of ectoparasitic drugs that may be appropriate for tx of body lice in short wool sheep? What sort of treatments are suitable for short wool vs long wool sheep?
IGRs, OPs, Spinosyns, Neonicotin, Mg fluorosilicate
Short wool: shower/ plunge dips, pour-on backliners
Long wool: Hand jetting or spray-on backliner
What 3 things must be followed to have any chance of eradicating body lice in sheep?
- All sheep must be treated
- Sheep must be treated at the same time
- Apply chemicals properly, according to label instructions
What time period should you be dipping short wool sheep in?
Between 10d and 4w off-shears
Compare backliners to dips for tx of bodylice in sheep?
Backliners are:
- quicker, less labour intensive, less stressful
- No water or plant needed
- no need for remuster
- no waste wash to dispose of
- fewer OHS concerns
- sheep are marked
- no dipping diseases
- may not be as effective
- more costly
