Infertility in the ewe and doe Flashcards
what % of ewes conceive in each mating
90% (much lower in lambs)
If PD sheep, when do you scan
70 days
How is reproductive performance measured in sheep?
Using the lambing or rearing percentage
Fertility definition
Whether the ewes become pregnant and go on to lamb
Fecundity definition
the number of lambs that are born per pregnancy
Non infectious causes of infertility
- stress
- large litter size
- drugs (PGF2a, steroids in late pregnancy)
- toxins
- diet (energy, iodine, mangnese)
- concurrent disease
- hyperadrenocorticism
Structural defects leading to infertility
Defects of the ovine genital tract are uncommon, with less than 1% showing macroscopic abnormalities.
Freemartinism is likely to be rare in sheep.
Management factors leading to infertility in sheep
These may include oestrus detection where AI is practiced, the correct use of teaser rams, the ram to ewe ratio and nutrition.
Functional factors leading to infertility
Except in unthrifty ewes anoestrus is uncommon (0.3%).
Embryonic death, or resorption, is an apparent feature of sheep infertility associated with multiple conception.
Early embryonic death is usually associated with infectious disease such as toxoplasmosis and Border disease.
Target body conditions for ewes at weaning
Hil: 2
Upland: 2
Lowland: 2.5
Target body conditions for ewes at tupping
Hill: 2.5
U
Target body conditions for ewes in mid-pregnancy
Hill: 2
Upland: 3
Lowland: 3.5
What will be the effect on fertility of low bodyweight and poor condition
Delays cyclicity and the onset of breeding
Target body conditions for ewes at lambing
Hill: 2
Upland: 2.5
Lowland: 3
Do younger ewes have higher or lower ovulation rates
lower
What is flushing?
Increasing nutrition with forage or concentrates before breeding increases both ovulation rate in ewes and sperm production in rams.
It is most effective when body condition is on target.
Improved nutrition is needed for at least one cycle (2–3 weeks) to influence ovaries to release more eggs.
What nutritional factor can increase ovulation rate?
High protein supply
How many ewes can one teaser ram run with?
100
Following conception when does implantation occur?
Does not occur for another 15 days
How long is a teaser ram in with the ewes before being replaced with entire males?
15-16 days
What is the effect of selenium deficiency or excessive phosphorus on fertility?
Increases embryo loss
when does 70% of foetal growth occur
last 8 weeks
Most frequent infectious cause of abortion
Enzootic abortion of ewes (EAE)
Main infectious causes of abortion
Enzootic abortion
Toxoplasmosis
Campylobacter
Salmonella
Listeriosis
Other
Aetiology of enzootic abortion of ewes
Chlamydia abortus
Is EAE zoonotic
yes
Clinical signs of EAE
Abortion with no premonitory signs
In the last 2 weeks of gestation
Lamb usually fresh with no autolytic changes
Ewes not usually ill
May show vaginal discharge
May retain foetal membranes
Some develop metritis post abortion
PM of EAE
Placenta acutely inflamed
Inter-cotyledonary allantochorion is oedematous, thickened and leathery
Degeneration and necrosis of the foetal cotyledons
Thick yellow deposits on the chorion
When during gestation does EAE cause abortion
If early in gestation it will cause abortion, if later it will lie dormant until the next pregnancy and then cause abortion
Diagnosis of EAE
Smears from infected inter-cotyledonary area and wet skin of foetus
Stained with ZN to detect intracellular inclusion bodies
Serology
Treatment of EAE
Antibiotics reduce but dont eliminate abortions
Long acting oxytetracycline repeated every 10-14 days until lambing
Control of EAE
Isolate and mark all infected ewes to help stop the spread
Keep a clean flock
Vaccinate (Enzovac)- usually 1-4 mo before tupping
What makes a flock high risk for EAE
> 5% abortion
Purchased animals from non-accredited flocks
Aetiology of toxoplasmosis
Toxoplasma gondii
Is toxoplasma zoonotic
yes
Effects at different stages of gestation of Toxoplasma
Early (60-70 days): foetal resorption
Mid gestation: abortion or death and mummification
After 120 days: stillbirth, weak, or normal lambs
PM of toxoplasmosis
Cotyledons are bright to dark red in colour with small white nodules (frosted stawberries)
Intercotyledonary areas appear normal
Diagnosis of toxoplasma
Clinical signs of barren ewes, abortion, stillbirths, and mummified or weak lambs
Giemsa or leishman stained smears of affected cotyledons
Treatment of Toxoplasma
Monensin in feed during pregnancy
Decoquinate
Sulphonamides during acute phase
Control of toxoplasma
Biocontainment measures
Vaccination with the S48 strain (Toxovac)
Aetiology of Campylobacteriosis
Campylobacter fetus subsp fetus and C. jejuni
Is Campylobacter zoonotic
Yes
Clinical signs of Campylobacter
Commonest in young or old ewes
Abortion in last 6 weeks
Rarely show other signs except for vulval swelling and reddish coloured vulval discharge
PM of campylobacter
Placentitis with oedema and necrosis or foetal cotyledons
Aborted foetus looks fresh, may have necrotic foci in liver
Main sources of C jejuni and C fetus subsp fetus respectively
Wildlife
Sheep
Diagnosis of campylobacter
Gram or modified ZN stained smears from placenta or foetal stomach contents
Treatment and control of campylobacter
Treat with antibiotic
Mix aborted ewes with those who have already lambed to build immunity
Prevent birds accessing feeding troughs
Keep flocks closed
Aetiology of salmonellosis
S. abortusovis
S. typhimurium
S. Dublin
S. montevideo
S. diarizonae
Occasionally exotic strains
Is salmonella zoonotic
Yes, except S. abortusovis
Disease profile at different stages of gestation of salmonella
Early gestation: barren ewes
Late pregnancy: abortion and the birth weak lambs
Affected ewes often ill, can recover to become symptomless carriers
Clinical signs of S. abortusovis
Few signs in ewes except abortion, usually in last 6 weeks
In lambs either: born weak and die in a few hours, or born healthy and suddenly become ill and die in first 10 days
Clinical signs for S. montevideo and S. diarizonae
Little systemic illness
Not as severe as S. dublin and S. typhurmurium
Abortion
Clinical signs of S. typhimurium
Ewes: anorexia, pyrexia, profuse scour, foul smelling discharge, death (septicaemia or dehydration)
lambs: may be born dead, or alive with signs of severe illness
Clinical signs of S. dublin
Not normally as severe as S. typhimurium
Death usually from septicaemia or dehydration
Mortality rates much lower
Diagnosis of Salmonella
Clinical signs
Culture from foetal stomach contents
FAT and serological tests
Treatment and control of salmonella
Isolate
Treat with antibiotic (C&S)
Regularly change feeding area
Avoid stressful situations arising in flock
Aetiology of Listeriosis
L. monocytogenes and occasionally L. ivanovii
Clinical signs of listeriosis
Encephalitis, abortion, diarrhoea with septicaemia, keratoconjunctivitis, mastitis, septicaemia ad death of young lambs.
Abortion can occur at any stage, more frequent in late pregnancy
May be pyrexic before abortion
Weak lambs often born
Ewe often has heavy brown discharge
PM of listeriosis
Grey/white focal necrosis in foetal liver
Placental villi are necrotic
Chorion covered with brownish red exudate
Likely exposure of listeria
Soil contaminated silage
Diagnosis of listeriosis
Isolation of organism
FAT
Treatment and control of listeria
Antibiotics
Do not feed poor silage to pregnant ewes
Aetiology or border disease
Pestivirus
‘hairy shaker disease’
Clinical signs of border disease
Lambs born with neurological disease and coarse fleece
Adults: mild pyrexia, abortion at any stage of gestation - brown mummified or swollen anasacous foetus
Common source of infection with border disease
Persistently infected animals - chronic shedders
Diagnosis of border disease
Clinical signs, histopathological examination of the brain and spinal cord
FAT and serology
Treatment and control of border disease
No treatment or vaccination available
Maintain a closed flock
Ensure non-pregnant ewes develop immunity
Aetiology of lepto
Leptospira spp. serovar hardjo
Disease in late gestation (abortion) and immediate post partum period in lambs
Clinical signs of lepto
Reproductive wastage, late abortion, stillbirths, and birth of weak lambs
Diagnosis of lepto
Isolation of organism from foetus or membranes using FAT
Paired serology
Treatment and control of lepto
If abortion storm treat ewes with dihydrostreptomycin as single dose
control attempted by vaccination
Minimise contact between sheep and cattle
Aetiology of brucellosis
Brucella melitensis and B. ovis
Is Brucellosis notifiable
Yes (malta fever in humans)
Clinical signs of brucellosis
Abortion, still birth, weak lambs
B. ovis causes epididymitis and subsequent infertility and sterility
Epidemiology of brucellosis
Direct ingestion of products of abortion
Diagnosis of brucellosis
Examination or culture of placental smears, foetal stomach contents or vaginal discharge
serology
Q-fever
rickettsia Coxiella burnetti
Not that significant in sheep farming but some outbreaks, important for public health
spread by aerosols from fleece or dust in lambing area (placenta and vaginal discharges are heavily contaminated
Ureaplasmas
Granular vulvaginitis
Infertility and abortion in cattle, maybe same in sheep
Ram often a major distributor of infection
Aetiology of tick borne fever
Cytoecetes phagocytophilia, limited to areas with Ixodes ricinus ticks
Clinical signs of tick borne fever
Abortion in adult sheep if infected in late pregnancy
Reabsorption if infected in early pregnancy
Clinical signs of tick borne fever
Abortion in adult sheep if infected in late pregnancy
Reabsorption if infected in early pregnancy
Diagnosis of tick borne fever
Identifying the organism in leucocytes of ewes that have aborted
Treatment and control of tickborne fever
Oxytetracycline for naive flock
Control ticks by dipping
Aetiology of bluetongue virus
Orbivirus infection, notifiable. Current outbreak is BTV-12 and BTV-3.
Clinical signs of bluetongue virus
Vascular damage leading to pyrexia, damage to the coronary band, salivation due to oedema and hyperaemia of the muzzle tongue and buccal mucosa
Abortion, early embryonic death, or the birth of dummy lambs
Epidemiology of bluetongue virus
Transmitted by culicoides midges, risk decreases as temp drops
Diagnosis of bluetongue virus
Antibodies using serology
Virus isolation or PCR
Treatment and control of bluetongue virus
Notifiable
Vaccination available
Aetiology of schmallenburg virus
Orthobunyavirus, endemic in UK now
Clinical signs of schmallenburg
No signs in infected ewes
1st half of gestation: resorption or mummification of foetus, maybe abortion
Malformed animals and stillbirths occur with congenital abnormalities
Diagnosis of schmallenburg
Serology or virus isolation
Control of schmallenburg
Control of vectors- try and keep midges out
Vaccines available
What should the barren rate of a flock be below
2% (greater than 4% warrants investigation)
Reasons for high barren rate
Poor conception rates due to females not cycling at beginning of the mating period or fertilisation failure
Early embryonic death (EED) due to infectious causes or related to nutrition
Ewe factors that can lead to poor conception rates
Appropriate mating time
Timing of synchronisation
Appropriate BCS
Trace element status
Stressors around tupping time
Size of replacement ewes
Lameness
GI parasites
Fluke
Brassicas
When should trace element status be tested in ewes?
Sample and supplement as required 6 weeks prior to tupping
What size should replacement ewes be?
Two thirds of their expected mature weight at tupping
What is the effect of brassicas on ewe fertility?
E.g. rape or kale
Antioestrogenic effect
Ram factors that can cause low fertility rates
BCS at tupping
Disease/infection/lameness in 6 weeks prior to and throughout tupping
BSE
Sufficient ram-power
Main causes of early embryonic death (7)
- Border disease
- Toxoplasmosis
- Subacute fluke
- Schmallenburg
- Selenium deficiency
- Iodine deficiency
- Tick borne fever
Testing for Border disease
Serology on barren ewes for antibody to BDV - remove PI animals
Testing for toxoplasmosis
Serology indicates past-infection – a single positive is not diagnostic for Toxoplasmosis; it only confirms that the animal has been exposed.
Serology on younger stock may be more sensitive.
Testing for subacute fluke
Faecal coproantigen testing, faecal worm egg counts and serology can be useful to detect infection.
Testing for schmallenburg
Serology indicates previous exposure.
Testing for selenium deficiency
Biochemistry can be used to assess selenium levels (by measuring GSH-Px) and should drive the need for pre-breeding trace element assessment next season.
Testing for iodine deficiency
Biochemistry can be used to assess plasma inorganic iodine levels.
Testing for tick borne fever
PCR indicates if animals are infected
Actions to take in cases of infertility
- BCS affected ewes and proportion of rest of flock
- Blood sample 6-10 affected animals for toxoplasma, EAE, Border disease
- If doubt over ram’s fertility have full fertility examination carried out and semen sample collected and assessed.
- Following year check body condition score of ewes two to four weeks pre-tupping and again post-tupping. (Rams should be body condition score of 3.5-4 at tupping).
- Blood sample four ewes for copper, vitamin B12 and selenium
Samples to submit for abortion testing
Section of placenta including more than 1 cotyledon, with large margins of inter-cotyledonary membranes
Foetal fluid collected from the thorax or abdomen
Foetal stomach contents collected aseptically
Fresh spleen
Steps to take after an abortion
Isolate the ewe
Initiate antibiotic therapy if indicated by ill health or RFM
Do not foster lambs onto ewes that have aborted
Mark ewes for management purposes
Submit material for investigation
Good hygiene and biosecurity
Cycle length of a doe
18-21 days
Oestrus duration doe
12-36 hours
Timing of ovulation of doe
24-36 hours after beginning of oestrus
Seaonality of goat breeding
February to June: Anoestrus.
July to August: Transitory period. September to February: Breeding season.
Can try out-of-season breeding with the help of artificial lighting, melatonin and progesterone sponges (need higher concentrations and apply for longer than in the ewe).
Signs of oestrus in does
Flagging of tail, bleating, slight temperament changes, vulval hyperaemia, little vaginal discharge, interest in male and male scent (e.g. scent using cloth).
Note: Mounting of other females is rarely seen.
Fertility of goats
Highly fertile: Pregnancy rates greater than 90% are possible.
Pregnancy diagnosis in goats
Methods include: Trans-abdominal ultrasonography from 30-50 days, oestrone sulphate in blood or milk from 45 days; radiography of foetal skeleton from 70-80 days.
Indirect methods: Non-return to oestrus, progesterone in milk or blood
Stages of parturition in goats
First stage: 6-12 hours.
Second stage: 0.5-1 hour.
Third stage: 3-4 hours.
Causes of anoestrus in maiden animals
Poor growth rate
Intersex
Anatomical abnormalities
Causes of anoestrus in any aged doe
Breeding out of season
Pregnancy
Lactational inhibition
Nutrition (NEB)
Ovarian malfunction (cystic ovarian disease)
Poor heat detection
Causes of infertility in does
Failure to stand (not in oestrus or fear of buck)
Herd problem (concurrent disease, nutrition, stress, sex ratios)
Uterine pathology (neoplasia, endometritis, aquired abnormalities)
Pseudopregnancy incidence
9%, up to 30% in some herds
Signs of pseudopregnancy
Abdominal distension
Udder development if non lactating
Sudden loss of fluid
Diagnose with ultrasound
Treatment of pseudopregnancy
PGF2a
Abortion in Angora goats
Syndrome linked with environmental stress and chronic energy deficiency
Endometritis
Inflammation of the endometrium only
Metritis
Inflammation of all layers of the uterus wall
Perimetritis
Inflammation of the serosal surface only
Pyometritis
Metritis and free purulent material in the lumen of the uterus
Bacterial causes of abortion (7)
Chlamydophila abortus
Campylobacter fetus
Salmonella
Listeria monocytogenes
Coxiella burnetti (Q fever)
Leptospira
Brucella melitensis
Parasitic causes of abortion
Toxoplasma gondii
What causes of abortion can a sample of placenta (multiple cotyledons and inter-cotyledonary membrane) be used to test for?
Gross examination for placentitis and stained smear:
- Chlamydia (EAE)
- Coxiella (Q-fever)
- Brucella
PCR: Toxoplasma gondii
What causes of abortion can a sample of foetal stomach contents (aseptically collected) be used to test for?
Bacteriology:
Any bacterial cause e.g. Campylobacter, Salmonella
What causes of abortion can a sample of foetal fluid (thoracic or abdominal) be used to test for?
Indirect fluorescent antibody test (iFAT):
- Toxoplasma gondii
What causes of abortion can a sample of foetal spleen be used to test for?
PCR:
- Border disease
What causes of abortion can a sample of foetal liver be used to test for?
Additional bacteriology:
- bacterial causes e.g. campylobacter
What causes of abortion can a sample of foetal brain be used to test for?
PCR:
- Schmallenburg
What causes of abortion can a sample of maternal serum be used to test for?
Antibody ELISA:
- Chlamydophila abortus
Latex agglutination test (LAT):
- Toxoplasma gondii
Antibody ELISA, PCR:
- Border disease
