Ovine Flashcards
When does puberty occur?
6-9 months at 60% of mature bodyweight
Describe the placenta
Caruncles and cotyledons - epitheliochorial
Name the 6 types of cervix
Duck bill Slit Rose Papilla Flap Spiral
Name the 4 types of AI
- Shot in the dark
- Intracervical
- Laproscopic (intrauterine)
- Over the rail
What types of breeders are sheep?
Short day
Seasonally polyoestrus
How long is the oestrus cycle?
14-19 (16) days
How long is oestrus?
24 hours average - shorter in maidens and longer in older years
When does ovulation occur?
24-30 horus after onset of oestrus (the end)
How long is the luteal phase?
13d
How many follicular waves per cycle?
3-4 per cycle
Oestrus behaviour examples
Seeking service
Stands for mounting
Sexually active groups seek the ram not other females
What is the gestation length in sheep?
145-150 days
When is IFN tau released?
Before 14 days - prevents PGF2a
When is the CL responsive?
50 days - only present for this long in the sheep (PGF2a use in sheep before this can abort pregnancy)
Name 2 substances released during maternal recognition of pregnancy and how do they do cause MRP?
- IFN tau (trophoblast)
- Ovine trophoblastic protein
Inhibit expression of oxytocin receptors -> no PGF2a -> CL remains
When can we diagnose pregnancy with ultrasound?
reliably >40d gestation
Where does pregnancy specific protein B come from and when?
Comes from binucleate giant cells in placenta
Can identify this from 14 days
What is the ratio for adult paddock matings?
1:50
What is the ratio for synchronised females in season?
1:10
What is the purpose of CIDR?
Produce progesterone and extend luteal phase
What is the purpose of sponges?
Progesterone release
How long are sponges or CIDRs inserted for and what is the process after their removal?
12-14 days
Inseminate 55 hours after removal
Spring joining -> inject 400IU eCG after removal
Frozen AI -> 400IU eCG and do laproscopic AI 55 hours after removal
Name 2 prostaglandin oestrus synchronisers
Lutalyse
Estrumate
What must be present in order for prostaglandin oestrus synchronisers to work?
A 5 day CL
What is the process of using Lutalyse and Estrumate?
2 injections 9-12 days apart
Oestrus occurs 2-4 days after second injection
What is the ram effect and when can it occur?
If ewes isolated for 1 month they respond to ram introduction with LH surge within 48 hours and ovulation 3-5 days after rams put in
First ovulation = silent -> will be in standing heat next time
When would you breed after using ram effect?
21d after ram introduction
Do remainder 28 days if some were silent
Is the ram effect suitable for fixed time AI?
No -> synchrony not right enough
Can use alonside drugs to enhance LH surge (when CIDRs are removed for example)
How much does the ram effect advance the season?
3-6 weeks
Example Ram Effect schedule
Day 0 -> teasers in 3-5 -> silent heat 14 -> teasers out rams in 21 -> early mating group 28 -> late mating group
How do we prepare teaser rams for the ram effect?
3 injections 2ml testosterone weekly
Last injection when turned in with the ewes
what are the conception rates for the shot in the dark method?
50% (vaginal AI)
What are the conception rates for over the rail?
65%
What are the conception rates for laparoscopy?
65%
What difference does increasing the sperm number make if we inseminate deeper than 1cm into the cervix?
3% difference in conception rates between 50 and 400 million sperm -> no point using a larger dose if we inseminate like this
If we are using fresh sperm, is there an ideal place to inseminate it?
No - vaginal, cervical and uterine yield the same conception rates with fresh sperm
When do rams go through puberty and what are 2 factors that affect this?
6 months -> birth time and breed
What age does a buck hit puberty?
3 months
What type of scrotum do rams have?
Pendulous
What accessory glands do rams have?
All
Name 5 factors affecting ram reproductive performace
- Nutrition
- Libido
- Sperm production (scrotal C.)
- Season effects
- Reproductive disease
What does obesity or anorexia cause in rams?
Loss of libido
Reduced sperm production
Reduced stamina
Which testis is larger in the ram?
The right is larger
Name 6 things we look for in scrotal pathology
- Scabies
- Photosensitisation
- Scrotal dermatitis
- Insect bites
- Allergic reactions
- Ectoparasites
Name 6 things that would cause us to cull a ram
- Epididymitis
- Pizzle rot
- Penile adhesions
- Cryptochidism
- Scrotal abcess
- Penile deviations
Name 2 testicular conditions in the ram
Brucellosis
Epididymitis
What is brucellosis and how do we test for it?
A venereal disease causing epididymitis in rams and thick necrotic placentitis in ewes
Reduced fertility/sterility
Test semen/blood
How do we diagnose epididymitis and what is it usually caused by?
Usually brucella ovis or A seminis infection
Palpate testis and epididymis
How does brucella ovis infect?
Enters systemic circulation via mucous membranes (vaginal, prepucial or conjunctival)
When does seroconversion occur with brucella ovis infection?
1-2 weeks post infection
When does shedding of brucella ovis occur in semen?
4-6 weeks post infection
List clinical signs in ewes of brucella ovis
Return to oestrus
25-35% abortions in affected flocks
Thick necrotic placentitis
No permanent infection
List 4 clinical signs of brucella ovis in the ram
Enlargement + fibrosis of epididymis
Reduced volume of testis
Semen culture and serology positive
Detached heads on spermiogram
How do we control brucella ovis?
palpate + cull
vaccinate
ELISA
Name 5 less common issues causing sub or infertility in the ram
- Developmental defects (wollfian duct issues)
- Spermiostasis (blind duct ends)
- Spermatocoele (cystic dilation of epididymal duct - sperm accumulation)
- Sperm granuloma - inflammatory reaction to sperm products
- Spermatic cord issues - abscess, hernia, tortion
What is a “good” scrotal circumference rating for an animal <14 months and >14 months old?
<14 months - 36cm
>14 months - 40cm
What is the duration of spermatogenesis and epididymal transit time in rams?
49 days
13-17 days transit
What is a ram’s daily sperm production?
10 x 10^9
What is the ideal volume, motility, morphology and concentration for a ram?
Volume - 0.5-1.5ml
Motility - 70-90%
Concentration - 2-5 x 10^9/ml
Morphology 70-90%
What is “satisfactory” motility and morphology for a ram?
> 30% motile
>50% morphology
what are 3 influences of the ram on the ram effect?
Age
Libido
depth of anestrum
Name 6 factors contributing to reproductive wastage in sheep
- Ram infertility
- failure to conceive
- abortion
- perinatal mortality
- ewe mortality
- embryonic mortality
What is the number 1 criteria of reproductive performance?
Lambs weaned per ewe joined
Name 5 things to consider in flock history/observation
- Rams working
- Concentration of lambing
- Pasture condition
- time of joining
- parasite control
4 factors reducing fertility at joining
- Anoestrus
- Failure of insemination
- Low ovulation rates
- Embryonic mortality
How to diagnose anoestrus (3)
- Ram harnesses should have 70% marked in first 14 days
- Long lambing season
- Non-pregnant ewes at lambing
5 reasons for failure of fertilisation
- Joining maidens + adults together
- Paddock topography (hills)
- Disease - B. ovis, A. seminis
- Oestrogenic pastures
- poor libido - lameness?
Signs of failure of fertilisation
- return to service
- drawn out lambing
- poor lambing %
Reasons for fertilisation failure with no return to service
Coming into season late in season
Lapsing back into anoestrus after ram effect
Signs -> poor lambing % with few returns to service
When does peak ovulation rate occur?
Autumn
What do phytooestrogens do and what produces them?
decrease multiple ovulation
Lucerne and clover pastures
What is “flushing” a ewe?
Grazing protein/energy supplements (lupins) that increases ovulation rate before joining
5 factors decreasing % lambs at marking
Abortion Dystocia Predation Starving, mismothering and exposure (MSE complex) Neonatal infection
Name 4 bacteria/protozoa causing abortion
- Campylobacteriosis
- Listeriosis
- Chlamydia
- Streptococcus
What does chlamydia do to sheep
Soil borne - get into placental tissues
vaginal and faecal swabs positive
When is listeriosis a risk?
on high pH silage
How is toxoplasmosis spread in sheep?
Cats are hosts - faeces eaten by ewe resulting in mid-late abortion and placental infection
Name 4 viral abortion pathogens
- Bluetongue
- Border disease
- Arboviruses
- Brucella ovis
When does bluetongue cause abortions?
Late gestation
When does border disease (similar to pestivirus) cause abortion?
<85 days gestation
Name 5 non-infectious causes of abortions
- Stressors and trauma
- Hyper/hypothermia
- protein calorie malnutrition
- Toxic plants
- Iodine or selenium deficiency
Name 5 causes of dystocia in sheep
- Hypocalcaemia
- Postural abnormalities
- Multiple births
- Parity (maidens)
- Fetal anasarca
Explain the SME complex
Starvation -> failure to suck (competition, weakness)
Mismothering -> multiple births, disturbance, inexperience
Exposure -> adverse lambing conditions, extreme temperatures, hypothermia
Name causes of neonatal infection
High stocking density
Umbilical, oronasal or transplacental infection
