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Reproduction > Sheep > Flashcards

Sheep Flashcards

1
Q

What is special about the sheep cervix?

A

There is wide variation- there is at least 6 different types. Both the external os and the cartilaginous rings can look completely different in each individual

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2
Q

Sperm travel in the cervix through “privlidged pathways” in little channels. How does this facilitate their movement?

A

There is retrograde flow of mucous through the cervix, and this is much faster in the lumen than in these channels.

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3
Q

What age do sheep hit puberty?

A

6-9 months

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4
Q

What is the target weight at puberty?

A

60% of mature BW

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5
Q

What is the mature weight of a Merino?

A

50-60kg

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6
Q

When is the natural breeding season for sheep?

A

During autumn (decreasing day lengths), mid-Feb to June

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7
Q

Ewes in oestrus will actively seek out the ram. T/F

A

TRUE

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8
Q

How long is the oestrus cycle in sheep?

A

14-19 days, mean 16.5

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9
Q

How many follicular waves are in an oestrus interval in a sheep?

A

3-4

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10
Q

How long does oestrus last for?

A

Approx a day- longer and more overt in the middle of breeding season

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11
Q

How long after onset of oestrus does ovulation occur?

A

25-30 hours- near the end of oestrus. Occurs around the same time as the LH surge, similar to cows

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12
Q

How long does the luteal phase last?

A

About 13 days- from like day 2 to day 14

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13
Q

When is the CL susceptible to PG?

A

From day 5 to day 55

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14
Q

Is the CL needed after 55 days?

A

No, from then on the pregnancy is maintained by feto-placental P4 production. So after this time to abort you need to use corticosteroids.

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15
Q

How long are goats dependent on the CL for?

A

The entire pregnancy

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16
Q

How can we synchronise ewes without drugs?

A

Using biostimulation, AKA the ram effect.
Ewes need to be isolated from a ram for at least a month. Then, when rams are reintroduced they have an LH sugre within 48 hours and aan ovulation about 30 hours later. Wethers treated with T4 and vasectomised rams have the same effect- to do with pheromones.

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17
Q

Using this ram stimulation, you will get two peaks in ovulation in ewes, when?

A

One peak at about 20 days and the other at about 25 days after you remove the ram. So about 3 weeks after removal a group will cycle, then a week later the 2nd group will cycle.

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18
Q

When should we use the ram effect?

A
  • When most or all ewes are not yet cycling
  • Within a few weeks of normal breeding season
  • When doing fresh insemination after raddling by a teaser
  • Can be used in association with drug induced synchronisation programs, introduce teasers when CIDRs are removed to enhance LH surge
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19
Q

When should we not use ram effect?

A
  • When doing fixed-time insemination because synchrony of ovulation is not “tight” enough
  • Effectiveness is also breed-dependent
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20
Q

How long prior to collection should the rams be trained with the AV?

A

AT least 3 weeks. The ram may also need to be quietened by hand feeding, which may take 1-2 weeks. Collect using AV during 3rd or 4th session. Let him serve a restrained ewe (on heat if possible) in the presence of an attendant.

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21
Q

In what stage of their cycle are they in if clear, sparse and runny mucous is observed?

A

Early oestrus

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22
Q

After 12-18 hours, the mucous changes and becomes….

A

Cloudy, copious and stringy.

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23
Q

25-30 hours after this second, stringy mucous, it changes and becomes….

A

Creamy, less copious and thick.

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24
Q

If the mucus is creamy when the ewes presents, what are the chances of a successful insemination?

A

POOR. Ovulation nromally occurs 25-30 hours after the onset of oestrus, and the oocyte degenerates within about 6 hours of ovulation, so if they present with creamy mucus it has likely already been too long.

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25
Q

What happens to CRs as you compromise the sperm, e.g. by freezing?

A

They decrease.

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26
Q

The highest pregnancy rates occur when semen is deposited…

A

Directly into the uterus

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27
Q

How much of the flock do we expect to be marked in the first 14 days, with the ram wearing a harness?

A

70% or more-> if this is not the case suspect anoestrus

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28
Q

How many rams are needed?

A

Generally 1.5%, so 2 for every 300 sheep. 2% for maidens. This needs to be more if the geography is difficult, e.g. hills, sparse watering points, bigger paddock. It also gets higher of breeding out of season, doing synchronisation.

29
Q

How do we tell if the ram has failed to inseminate the ewe?

A

Large number of ewes return to service

30
Q

What conditions does brucella ovis cause in the male?

A

It causes brucellosis. This can cause occlusion of the epididymus (which is only one tube) so the sperm can’t escape, causing epididymitis.

31
Q

Not all epididymitis is caused by brucella ovis. What else can cause it?

A

A. seminis, also Histophilus ovis and Corynebacterium spp. It can also have traumatic causes, e.g. grass sees, fighting, shearing cuts

32
Q

How does brucella ovis spread?

A

This is a venereal pathogen. It is spread in semen, from ram to the ewe and then to another ram. It can also spread ram to ram. It causes a decrease in semen quality, and therefore subfertility.

33
Q

What can cause low ovulation rates?

A

Season- peak ovulation rate occurs in Autumn
Breed/genotype, e.g. Booroola (2.7) vs Merino (1.1)
Low bodyweight or CS
Age- adults have a greater ov rate cf to maidens
Coumestans (lucerne) decreases multiple ovulation
Nutrition- protein/energy supplement, e.g. Lupins, increases ov rate. Flushing effect- grazing conditions just before joining which is independent of bodyweight

34
Q

What are signs of a low ovulation rate?

A
  • Low lamb marking percentage
  • Low % of twins- commonly 10-20% in Merinos
35
Q

What are two important abortifacient agents for small ruminants in Aus? (Hint… campy…)

A

Campylobacter fetus fetus and Campylobacter jejuni

36
Q

What are some examples of viruses that cause abortion in sheep?

A

Border Disease- similar to BVDV
Arboviruses- e.g. Akabane, Cache Valley Virus

37
Q

What is the Brucella agent that affects goats?

A

B. melitensis

38
Q

What are 8 things that can cause non-infectious abortions in sheep?

A
  • Stressors and/or trauma (peri-mating and -parturient)
  • Hyper or hypothermia-> this is a big problems in lambs
  • PCM (Protein calorie malnutrition= energy)
  • Overfeeding adolescent ewes (fatty liver) –> preg tox. Underfeeding is also a problem
  • Toxic plants
  • I deficiency
  • Se seficiency
  • Other nutrient imbalances
39
Q

The “reasonable/normal” level of neonatal losses is quite high in Aus. What is it?

A

Up to 30%

40
Q

Why does Aus have such high neonatal mortality rates?

A
  • We tend to breed them out of season, really harsh cold conditions. Lambs get cold, mismothering, lack of colostrum for whatever reason
  • A lot of farmers will not observe lambing so as not to “disrupt the lambing bond”
  • Selection pressure not necessarily the same for breeding good wool and good mothering- we might sacrifice some of the mothering skills in favour of breeding for good wool or meat
41
Q

Freemartinism only occurs in cattle. T/F

A

FALSE- it can occur in ALL species, just not necessarily at the same rates

42
Q

Around what age do rams reach puberty?

A

About 6 months

43
Q

Around what age do bucks reach puberty?

A

Around 4-5 months, and about 2-3 months in pygmy breeds

44
Q

What factors can affect the age at which rams reach puberty?

A
  • Breed and DOB (cause they’re seasonal animals, it depends on when they’re born)
  • Faster if exposed to oestrus ewes
45
Q

At 6 months, rams have high capability for high pregnancy rates. T/F

A

FALSE. At this point they’ve only just reached puberty, and sperm quantity and quality are still low.

46
Q

Ruminants have a fibroelastic penis. Does this increase in length during ejaculation?

A

NO

47
Q

What is the function of the glans penis?

A

This is a worm-like appendage that sprays semen around the female repro tract. Rams can be fertile without it.

48
Q

What things are assessed in the physical exam as part of the ram breeding soundness evaluation?

A

General- how does he walk? Conformation? BCS?
The 4 Ts- Teeth, Toes, Testes (and scrotum) and Tossle

49
Q

What affect does obesity have on fertility of rams?

A
  • Loss of libido/reduced stamina
  • Reduced sperm production
  • Physical mating problems
    –> SEXUAL ATHLETES
50
Q

What affect does being underweight have on fertility of rams?

A
  • Loss of libido/reduced stamina
  • Reduced sperm production
51
Q

Why is it bad if rams have lameness?

A
  • Can’t keep up- esp. in extensive pastures
  • Can’t support body weight
  • Can’t graze
52
Q

Why is lameness often exacerbated for rams and pregnant ewes?

A
  • Because they’re heavier- e.g. interdigital dermatitis will affect the ewe more when she’s more heavily pregnant cause she weighs more
53
Q

What are 5 causes of lameness in sheep?

A
  • Footrot
  • Abscess
  • Muscle strain
  • Fracture
  • Overgrown hooves
    It is often debatable for rams whether you fix these or just cull them, cause they may pass these issue into their offspring.
54
Q

Why are conditions such as varicocoele, spermatocoele, funiculitis (inflammation of spermatic cord), scrotal dermatitis etc bad for sperm production?

A

They adversely affect thermoregulation of testes because of compromised epithelium and buildup of fluid etc, which adversely affects sperm production.

55
Q

In rams, which teste is NORMALLY bigger than the other?

A

The right is usually larger than the left. BUT it shouldn’t be a big discrepancy.

56
Q

Tone of testes should be assessed in a BSE. What should they feel like?

A
  • Not hard, not soft, not spongy, should feel like pushing on the pad of your thumb
57
Q

There are 6 conditions which if present we would cull the ram. What are they?

A
  • Cryptorchidism
  • Herniation
  • Epididymitis
  • Scrotal abscess
  • SEVERE pizzle rot
  • Penile adhesion/deviations
58
Q

What causes pizzle rot?

A
  • Corynebacterium spp, such as corynebacterium renale. Also increases in protein in feed which causes increased urea in urine.
59
Q

How can we diagnose brucellosis?

A

Bacteriology test of semen/blood

60
Q

Is brucella ovis a zoonosis?

A

NO, not typically

61
Q

How long after rams becomes infected with B. ovis does the disease begin to shed in the semen?

A

4 weeks. They generally develop immunity about 2 weeks after that.

62
Q

What is balanitis?

A

Inflammation of penis

63
Q

What is posthitis?

A

Inflammation of prepuce

64
Q

What is balanoposthitis?

A

Concurrent inflammation of penis and prepuce- these do very often occur together.

65
Q

What is a good scrotal circumference?

A

Typically >32 cm means it’s likely to be good to use. Less than 32cm means either too young or questionable.

66
Q

How long does spermatogenesis take in a ram?

A

49 days

67
Q

What is the epididymal transit time in rams?

A

13-17 days

68
Q

What vol of semen is generally needed?

A

0.5-1.5mL

Reproduction (10 decks)

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