Small Ruminant Repro Flashcards
What is meant by the seasonaility of ewe breeding?
Length of breeding season depends on intrinsic circannual rhythm & photoperiod
Photoperiod affects via retinal photoreceptors in eye = nerves = pineal gland = melatonin secretion. Lamb in spring after the sun has kicked in the cycle.
The more developed breeds e.g. texel or Suffolk have less of a tight window unlike the hill breeds e.g. swaledale
How long is the sheep oestrus cycle?
•Oestrus cycle is 17 days (range 14-18) but <12d common as go from anoestrus to season
How long is the sheep luteal and follicular phase?
•Luteal phase is 13 days & Follicular phase 3-4 days
When is sheep ovulation and how long does it last?
•Ovulation is spontaneous at the end of oestrus which lasts ~30h
What is meant about the sheep year and what may the effect be of a cold lambing?
What are the 5 key performance indicators?
- Conception rates of ewes is very high (>90% to first service)
- With sufficient ‘ram power’, there should be <2% barren ewes after two cycles. 5% tink something is happening. 8%+ you have a problem – too many ewes? Poor ram?
- Abortion rates of up to 2% are acceptable? A bump or knock may account for 2%. Over 2% you have an infectious cause! If they start aborting a few weeks before lambing – huge problems. Enozootic, salmonella, toxo, border
- Infectious abortion very important, structural/functional & management factors of limited importance
- Individual non-pedigree sheep that don’t breed as shearlings should be culled as many don’t breed the following year. It is more about floc/population medicine
What are the zoonotic risks of lambing? (6)
include: Source, route and conequence
What are the risk facotrs for acute mastitis? (4)
Teat lesions - lamb teeth damage, Orf infection or S aureus lesions, Poor udder anatomy & teat placement
Chilling of the udder (windy weather, lack of shelter, excessive crutching, short tail docking)
Mismatch of supply and demand of milk. Poor nutrition leads to poor milk supply and udder bruising from lamb competition. More common in ewes with triplets or shearlings with twins.
4-5% incidence in lowland, <1% on hill. Usually in 6 weeks post lambing
What is seen with acute mastitis?
Often rapid onset gangrenous ‘black bag’ showing as hind leg lameness, depression, inappetence.
Udder painful & swollen, red®purple®black & cold
If the ewe survives, the black necrotic bag will slough off with lengthy healing (euthanasia?)
Milk changes (watery, flakes, clots)
Depressed, inappetant & lame ewe.
How do we treat acute mastitis?
Rapid treatment with antibiotic and NSAID may save ewe’s life (rarely save the udder)
Rapid treatment with antibiotic (tilmicosin amoxycillin, oxytetracycline) & NSAID required.
Why does mastitis preent so acutely in sheep?
Seem severe in sheep – they are a pray animal. Also we aren’t doing the milking everyday like cows so will miss the mild mastitis.
What is the prevelance of chronic mastitis?
When is it found?
Flock prevalence = 1%-15%
Major cause of culling ewes
Found at weaning, culling or even next lambing – abscesses in bag or thick fibrous cord in teat canal
Probably a result of undetected mastitis in lactation
What do we look at in the ram repro exam? (9)
- Body condition score - What is ideal? Not too fat, not too thin 3-4 out of 5
- Conformation- How does he stand? Fleece Brisket sore, Limb soundness
- Eyes, Teeth, Neck for lumps & bumps, Lympadenitis
- Ability of scrotum to keep testes cool
- Neck of scrotum
Testes & epididymes
- Must get ram to sit squarely to fully extrude penis
- Check for vasectomy scars, prepuce for injuries, ulcers, deformities
- Examine glans & vermiform appendage for injuries, ulcers etc & to prove penis can be fully extended
How do we measure scrotal size and what is normal?
Measure at the widest point
with consistent tension
Smaller doesn’t mean less quality. But it does mean he cannot serve as many! = more expense on ram power
Minimum acceptable scrotal circumference within 3 weeks of breeding season:
What is the pre breeding exam of a ram?
Post ram exam, what are the three outcomes?
What are the clincal signs of urolithiasis? (9)
Abdominal pain & anorexia
Teeth-grinding or bleating
Inability to pass urine
Crystals around preputial orifice
Swollen prepuce (urine leakage)
Wide-based stance, hind legs back, frequent stretching
Blockage at ischial arch or vermiform appendage on penis
Bladder rarely ruptures but urine leaks out into peritoneum
What is seen on ultrasound with urolithiasis? (2)
Distended bladder (>10cm beyond pelvis)
Urine in peritoneum & hydronephrosis of right kidney
What is this?
Swelling, blood-stained urine & crystals on preputial hairs Photo
What are uroliths?
Precipitation of insoluble salts of magnesium, ammonium & phosphates (calculi) which form a sludge with protein in urinary tract
What are the risk factors for urolithiasis? (7)
Wether lambs more likely than rams
High concentrate feeding levels (high P availability)
Low forage intake (forage reduces P availability)
High P in diet (>4.6g/kg DM) or high Mg (>2.3g/kg DM)
Low ratio of Ca:P (<1.5:1) (this increases P absorption)
Low water intake (increases urine concentration)
Genetics (Texels v efficient absorb dietary P & excreting in urine.)
What is this?
Swelling & necrosis of vermiform appendage
How do you treat urolithiasis? (4)
Muscle relaxants.Retrograde catheterisn
Excision of vermiform appendage
Surgery rarely useful as salvage
If they are fattening lambs you wil not be doing surgery. Can put things in the feed to encourage drinking and flushing e.g. ammonium or NaCl
How do you prevent calculi forming? (6)
Feed less concentrate & more forage
Ensure adequate water intake
Feed low P (<4.6g/kg DM) & low Mg (<2.3g/kg DM)
Ensure ratio of Ca:P is at least 2:1 (pref 3:1)
Include 1.5% salt in diet to increase water intake (total Na content at 6g/kg DM)
Include 1.5% ammonium chloride in diet to acidify urine
What can be seen here?
Hydronephrosis caused by back pressure; enlarged renal pelvis & ureter. Cf normal kidney.
What causes Balanoposthitis in the ram?
Caused by Corynebacterium renale & associated with high dietary protein (C renale produces enzyme urease which hydrolyses urea Þ ammonia)
Where is Balanoposthitis in the ram more common?
More common in wethers as penis less developed so likely to urinate into prepuce. Esp if fed on high protein pasture or barley & maize gluten concentrate
What is seen with Balanoposthitis in the ram?
Initially small necrotic ulcers at sheath margin Þ Painful, swollen lesions of sheath. Strong smell of ammonia. Sheep recumbent & inappetant. Risk of fly strike
What is this?
Posthitis with ulceration & necrosis of prepuce
How do you treat/control Balanoposthitis in the ram? (4)
Reduce protein in diet
Reduce feed intake but encourage intake of plenty of water
Aim to acidify urine (Ammonium chloride per os)
Give topical antiseptic & systemic antibiotics
What is this?
Scab formation and bleeding of
prepuce following orf infection
