Small Ruminant Repro

Question 1

What is meant by the seasonaility of ewe breeding?

Answer 1

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

Question 2

How long is the sheep oestrus cycle?

Answer 2

•Oestrus cycle is 17 days (range 14-18) but <12d common as go from anoestrus to season

Question 3

How long is the sheep luteal and follicular phase?

Answer 3

•Luteal phase is 13 days & Follicular phase 3-4 days

Question 4

When is sheep ovulation and how long does it last?

Answer 4

•Ovulation is spontaneous at the end of oestrus which lasts ~30h

Question 5

What is meant about the sheep year and what may the effect be of a cold lambing?

Answer 5

Question 6

What are the 5 key performance indicators?

Answer 6

1. Conception rates of ewes is very high (>90% to first service)
2. 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?
3. 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
4. Infectious abortion very important, structural/functional & management factors of limited importance
5. 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

Question 7

What are the zoonotic risks of lambing? (6)

include: Source, route and conequence

Answer 7

Question 8

What are the risk facotrs for acute mastitis? (4)

Answer 8

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

Question 9

What is seen with acute mastitis?

Answer 9

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.

Question 10

How do we treat acute mastitis?

Answer 10

Rapid treatment with antibiotic and NSAID may save ewe’s life (rarely save the udder)

Rapid treatment with antibiotic (tilmicosin amoxycillin, oxytetracycline) & NSAID required.

Question 11

Why does mastitis preent so acutely in sheep?

Answer 11

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.

Question 12

What is the prevelance of chronic mastitis?

When is it found?

Answer 12

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

Question 13

What do we look at in the ram repro exam? (9)

Answer 13

• 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

Question 14

How do we measure scrotal size and what is normal?

Answer 14

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:

Question 15

What is the pre breeding exam of a ram?

Answer 15

Question 16

Post ram exam, what are the three outcomes?

Answer 16

Question 17

What are the clincal signs of urolithiasis? (9)

Answer 17

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

Question 18

What is seen on ultrasound with urolithiasis? (2)

Answer 18

Distended bladder (>10cm beyond pelvis)

Urine in peritoneum & hydronephrosis of right kidney

Question 19

What is this?

Answer 19

Swelling, blood-stained urine & crystals on preputial hairs Photo

Question 20

What are uroliths?

Answer 20

Precipitation of insoluble salts of magnesium, ammonium & phosphates (calculi) which form a sludge with protein in urinary tract

Question 21

What are the risk factors for urolithiasis? (7)

Answer 21

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.)

Question 22

What is this?

Answer 22

Swelling & necrosis of vermiform appendage

Question 23

How do you treat urolithiasis? (4)

Answer 23

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

Question 24

How do you prevent calculi forming? (6)

Answer 24

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

Question 25

What can be seen here?

Answer 25

Hydronephrosis caused by back pressure; enlarged renal pelvis & ureter. Cf normal kidney.

Question 26

What causes Balanoposthitis in the ram?

Answer 26

Caused by Corynebacterium renale & associated with high dietary protein (C renale produces enzyme urease which hydrolyses urea Þ ammonia)

Question 27

Where is Balanoposthitis in the ram more common?

Answer 27

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

Question 28

What is seen with Balanoposthitis in the ram?

Answer 28

Initially small necrotic ulcers at sheath margin Þ Painful, swollen lesions of sheath. Strong smell of ammonia. Sheep recumbent & inappetant. Risk of fly strike

Question 29

What is this?

Answer 29

Posthitis with ulceration & necrosis of prepuce

Question 30

How do you treat/control Balanoposthitis in the ram? (4)

Answer 30

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

Question 31

What is this?

Answer 31

Scab formation and bleeding of

prepuce following orf infection