Repro Flashcards
Are heterozygotes or homozygotes more fertile?
Heterozygotes
Homozygotes less fertile or infertile
Name 3 repro conditions overweight ewes may be prone to
Dystocia
Pregnancy toxaemia
Prolapse
How is AI done in sheep?
Via laparoscope (due to cervix)
When manipulating seasonality in sheep, you can give Regulin. What is this and after how long should you introduce the ram?
Melatonin implant in ear
Introduce ram after 1 month
What is chronogest? How long is it intravaginal for and when should tupping occur?
Synthetic progesterone sponge
Intravaginal for 12-14 days
Tupping 48 hours after removal
Prostaglandin is not authorised in sheep for oestrus manipulation, but may be used. How many days apart should the injections be and when does oestrus occur?
2 injections 7-11 days apart
Oestrus occurs within 40 hours
Which drug can induce lambing and from how many days pregnancy?
Dexamethasone
140d + (last 2 weeks)
Is dexamethasone licensed to induce parturition in sheep? When can it be used?
No
Can only be used if service date know
When can scanning for PD occur in ewes?
70-120d after ram in
Or 28d after ram out
How does BCS and liveweight affect ovulation rate? (‘the static and dynamic effect’)
Higher BCS and higher liveweight = higher ovulation rate
What BCS should a ram be prior to tupping season?
3.5+
What scrotal circumference should a ram have prior to tupping?
30cm
What is Pizzle rot and what pathogen causes it?
Balanoposthitis - inflm of penis and prepuce
Due to urination inside prepuce
Corynebacterium renale
What is the biggest risk factor for developing Pizzle rot/balanoposthitis?
Castration at young age
Balanoposthitis/pizzle rot may cause ulcers, discharge, scabbig and blockage or even flystrike. Name some risk factors for this condition
Castration at a young age!!!
High protein concentration diet
Lush grass
Acidic urine - access to water, salt or ammonium chloride
What is the treatment for balanoposthitis/pizzle rot?
Isolate
Clean and clip
Systemic ABs
+/- fly treatment
What is a ‘rig’? Can they be used?
Cryptorchid ram
May be less fertile - put with fewer ewes or castrate - hereditary?
Inguinal hernias in rams are usually unilateral. How are they treated?
Surgical repair and castration (hereditary)
What mite causes scrotal mange? Where else may it occur?
Chorioptes bovis
Lower leggs and poll
Does Chorioptes (scrotal mange) affect fertility?
Yes if extensive
How is scrotal mange/Chorioptes diagnosed and treated?
Dx: skin scrape
Tx: doramectin (longer lasting than ivermectin) or diazinon
What triggers testicular degeneration in sheep?
Stress
Inflammation
High BCS
High temperature
Is testicular degeneration permanent?
No - causes poor fertility in first year
Return to soundness in 3 months as new sperm develop
How long does spermatogenesis take in a ram?
49 days
What is the average ewe cycle length?
17 days
Give 2 examples of what may cause testicular hypoplasia
Cryptorchidism
Hereditary disorder - XXY chromosome
What are the 3 most common abortive agents in sheep?
Chlamydophila abortus
Toxoplasmosis
Campylobacter
