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Y4 Farm Reproduction > Principle causes of infertility in the male > Flashcards

Principle causes of infertility in the male Flashcards

Male infertility and BSE

1
Q

History qs

A
  • Has he ever been used successfully? How long ago?
  • How old is he?
  • How many females has he been with and when?
  • Were they in good breeding condition?
  • Did females breed successfully with other males or A.I.?
  • Is he home-bred or bought/hired in? When?
  • Has he had febrile disease or treatment recently?
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2
Q

Clinical examination

A

Physical ailment may result in sub-fertility and infertility. Injury or disease may cause an infertility which appears as a subfertility if it affects the male part way through a breeding cycle.

  • Whole animal clinical exam not just the reproductive system
  • Observe from a distance – lameness, posture, demeanour
  • TPR and BCS
  • Teeth to check age/alignment
  • Eyes check for cataracts
  • Brisket – check for sores – will not mount with sore brisket
  • Legs check range of movement and any indication of pain in legs as well as feet
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3
Q

Body Condition Score (BCS)

A
  • On the 5 point plan
  • Bulls and rams that are in BCS 2 or less should be deemed unsatisfactory in this section as they are unlikely to be able to perform adequately during an intensive breeding period
  • Bulls and rams that are obese (>4) may suffer from poor semen quality due to deposition of fat in the scrotum leading to thermo-regulation problems
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4
Q

Legs - post-legged

A
  • increased risk of lameness due to hock, stifle or hip joint pathology
  • young bulls showing this conformation should be avoided
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5
Q

Legs - puffy hocks

A
  • Swollen hocks due to excessive synovial fluid are not uncommon in intensively reared young bulls less than 2 years old.
  • Distension of the hock joint may be caused by osteochondrosis which if mild may not be causing any lameness. Progression to osteochondritis dissecans (OCD) is possible in some bulls so bulls with swollen hocks and lameness are not suitable for breeding
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6
Q

Feet

A
  • a study showed that feet and leg abnormalities that didn’t cause lameness weren’t significantly associated with semen quality but may affect libido
  • only 4/17 lame bulls in the same study had satisfactory semen
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7
Q

Scrotal examination

A
  • Scrotal shape: straight sided, normal (pendulous), wedge-shaped
  • Testis should move easily within the scrotum, if not then adhesions are indicators of previous infection and inflammation
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8
Q

Conditions of the scrotum

A
  • Orchitis
  • Dermatitis
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9
Q

Conditions of the testicles

A
  • Hypoplasia (bilateral/unilateral, congenital can be due to abnormality of blood supply (Belgian Blue bulls)
  • Hard and possibly small due to post-traumatic scarring or fibrosis/calcification with age
  • Soft due to tubular atrophy (including non- breeding season)
  • Absent – cryptorchid
  • Rotated – stallion. Not significant.
  • Enlarged – neoplasia, especially older dogs
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10
Q

Cause of orchitis & how does the scrotum feel?

A
  • firm/painful
  • Brucella Ovis in rams causes orchitis as a primary symptom (NOTIFIABLE)
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11
Q

Cause of scrotal dermatitis

A
  • Chorioptic mange is the most common cause in rams
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12
Q

Why is scrotal circumference a critical component of PBE in bulls?

A
  • SC measurement is highly correlated to paired testes weight, daily sperm production and semen quality
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13
Q

How heritable is the SC measurement at 1-2ys of age in bulls?

A
  • moderately to highly heritable
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14
Q

Do bulls with above average SC reach puberty earlier or later than those with average or below?

A
  • earlier
  • this trait can be passed to female offspring
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15
Q

SC of rams

A
  • should be >33cm
  • should be >30cm for a ram lamb
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16
Q

UK BCVA SC standards

A
  • BCVA Bull PBE certificate bulls can pass SC standards for certification if they achieve the relevant breed standards for age
  • For most breeds this will be similar or indeed greater than the SFT standards but for others, SC standards may be lower (eg British Blue, Limousin).
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17
Q

Conditions of the epididymis

A
  • Lumpy, esp. ascending infection (mainly ram-epididymitis), blockage (spermatocoele)
  • Floppy, small, possibly displaced cauda
  • Absence (segmental aplasia of mesonephric duct)
  • Don’t just measure; palpate
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18
Q

Conditions of the prepuce

A
  • Penile rupture/haematoma
  • Preputial laceration/avulsion
  • Prolapse of prepuce
  • Urolithiasisis – crystals on preapical hair
  • Absent musculature in bulls/Too tight
    musculature can prevent intromission – hard to
    palpate
  • Phimosis and paraphimosis
  • Infectious balanitis
  • Trauma and foreign bodies
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19
Q

Conditions of the penis

A
  • Corkscrew penis in bulls
  • Trauma (all species, but especially stallion)
  • Rupture at the sigmoid flexure (ruminants)
  • Papillomas and other tumours
  • Persistent frenulum
  • ‘Pizzle rot’ (Rams)
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20
Q

What is ‘Pizzle rot’?

A
  • Corynebacterium renale
  • grows in the alkaline environment caused by the high urinary urea content of rams on high protein diets (posthitis)
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21
Q

Papillomas & other tumours of the penis

A
  • sometimes self- cure
  • can often be ligated in bulls
  • Squamous cell carcinoma at urethral orifice in stallions
  • fibroblastic sarcoids on penile/preputial skin
  • Transmissible Venereal Granuloma in dogs.
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22
Q

Examination of the accessory sex glands

A
  • Digital in Ram
  • Rectal in bull/stallion
  • Ultrasound
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23
Q

Conditions of the accessory sex glands - Seminal vesiculitis

A
  • typically yearling bulls;
    can become refractory to treatment; diagnose & treat early.
  • Tulathromycin weekly for 6 weeks;
  • Meloxicam by injection alternate days for
    first 2 weeks.
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24
Q

Infectious causes of male infertility in cattle

A

Viral
* IBR, BVD, EBL, Bluetongue

Bacterial
* Campylobacter, Brucella, TB, Lepto, Johne’s, Mycoplasma, Ureaplasma
* Protozoal
* Trichomonas

Anything resulting in pyrexia

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25
Q

Infectious causes of male infertility in sheep

A

Viral
* Bluetongue and possible Schmallenberg.

Bacterial
* Brucella ovis (notifiable), possible Johne’s, Mycoplasma, Ureaplasma

Anything resulting in pyrexia

26
Q

How long does any febrile condition or corticosteroid tx likely result in reduced semen quality?

A

4-6w after fever/tx

27
Q

Semen collection

A
  • Artificial vagina – Ruminants, stallions, boars
  • Digital manipulation – Boars
  • Electro-ejaculation – Most common method in Rams and Bulls
28
Q

Rams vs Bulls semen collection

A
  • Rams are seasonal, bulls are not
  • Rams have higher ‘workload’ ewe:ram ratio (up to 120 ewes per ram for some breeds)
  • Most infertility in rams can be detected from the physical exam, with bulls, semen examination almost always required
  • Rams - Semen collection by electro-ejaculator is painful in rams and must only be used when absolutely necessary not as a routine test. Analgesia is recommended and collection via artificial vagina is recommended to provide a more representative sample without the welfare concerns
29
Q

AI & Biosecurity

A
  • Regular testing of bulls on stud (often monthly while producing)
  • All semen must be frozen and is subject to 28-day quarantine
    period before distribution BUT
  • For domestic use, bulls can be collected on farm and only bTB, Brucella and EBL tests are required by law
30
Q

Semen analysis - gross examination

A
  • Good microscope
  • Warm stage – essential to
    avoid cold shock to sperm - Warm slides
  • Good smears
31
Q

Semen analysis - Ram - volume

A
  • Volume = 0.5-2.5ml relate to ram age, size and breed, testicle size
32
Q

Semen analysis - Ram - colour/concentration

A

Colour = Concentration + Contamination
* white – yellow = normal.
* brownish = blood,
* greenish = Pseudomonas aeruginosa,
* clots or mucus = pus and inflammation.

33
Q

Semen analysis - Ram - density

A
  • Density = 2500 – 5000 million sperm/ml (use of EEJ can result in a sample more dilute than would have been collected with AV)
  • Watery - density <500 million sperm/ml
  • Skim milk like - density 1000+/- 500 million sperm/ml
  • Milky - density 2000+/- 500 million sperm/ml
  • Thin creamy - density 3000+/- 500 million sperm/ml
  • Creamy - density 4000+/- 500 million sperm/ml
  • Thick creamy - density 5000+/- 500 million sperm/ml
34
Q

Semen analysis - Ram - motility

A
  • Motility = 70 – 95 %
35
Q

Microscopic examination - gross motility

A
  • Gross motility is assessed by placing a 5-10mm drop of the fresh semen sample on a clean warmed slide and examining under low power brightfield magnification.
  • Gross motility is scored subjectively on a five point scale
  • Gross motility depends on three factors: concentration, % progressively motile sperm and speed of progression of sperm.
36
Q

Microscopic examination - gross motility 5 point scale

A

Scale 1: no swirl, generalised oscillation of individual sperm only

Scale 2: very slow distinct swirl

Scale 3: slow distinct swirl

Scale 4: moderate fast distinct swirl, dark waves

Scale 5: fast, distinct swirls with continuous dark waves

37
Q

Microscopic examination - Progressive motility

A
  • After gross motility has been scored, a small drop (2-4mm) of semen is placed on a clean warm slide and covered with a warmed cover slip.
  • Examination under x 200 - x400 magnification will allow an estimation of % progressive forward motility
  • The standard required to pass the semen examination section of the BCVA PBE certificate is a progressive motility of > 60%
38
Q

Sperm morphology - minimum progressive motility and minimum % of morphologically normal sperm to pass semen examination

A
  • As well as having a minimum of 60% progressive motility, the semen sample must have a minimum of 70% morphologically normal sperm to pass the semen examination section.
  • Bulls with >20% nuclear (head) defects in a morphology counts should also be deemed unsatisfactory.
39
Q

Why must the assessment of sperm morphology be done in all cases?

A
  • Even when motility is excellent, some sperm defects do not impair motility but have significant effect on fertilising capacity eg.nuclear vacuoles.
40
Q

Sperm morphology - how to

A
  • To make a smear a small 5-6 mm drop of eosin-nigrosin stain is placed at one end of a warm, frosted-end slide and using a fine dropper or insulin syringe a small drop of semen is mixed with the stain.
  • After a short period the smear is made by pulling the drop of stain/semen along the slide with the edge of another slide
  • Morphology counts must be done under x1000 oil immersion magnification either with stained slides and brightfield microscopy or using fresh, wet (formol saline killed) preparations and phase contrast microscopy
41
Q

Sperm Morphology - proximal cytoplasmic droplets

A
  • Most sperm have a cytoplasmic droplet present when entering the caput epididymis but normally the droplets are shed during epididymal transport.
  • Proximal droplets present in ejaculated sperm are therefore not normal and a sign of disturbed epididymal or testicular function.
  • If present in high numbers they are likely to lead to reduced fertility though the mechanism of this is not clear.
  • Immature/pubertal bulls may produce ejaculates with a higher then normal % of sperm with proximal droplets.
42
Q

Sperm Morphology - detached heads

A
  • Small numbers of detached heads are seen in most semen samples however this defect can be present in high numbers in cases of sperm accumulation/senescence (rusty load).
  • If sperm accumulate abnormally in the cauda epididymis then the ejaculate may appear dense but often contains a high % of dead sperm and detached heads leading to poor motility.
  • These can often be cleared after several ejaculates but if they persist then they may be present due to stress, abnormal testicular thermoregulation or if present along with other sperm defects, due to testicular or accessory gland pathology.
43
Q

Sperm Morphology - Distal Midpiece Reflex / Bent Tails

A
  • This is the commonest abnormality of the sperm tail seen in bull semen and originates during sperm maturation in the epididymis.
  • The defect produces a bent tail of between 90-180° that occurs at the junction of the distal midpiece and principal piece.
  • A cytoplasmic drop is normally trapped at the bend.
  • The effect on fertility will be related to the % of the defect
    present as these sperm are not progressively motile.
  • This defect must be differentiated from simple bent
    tails which may be caused by mishandling of semen samples or exposing semen to hypotonic shock.
44
Q

Sperm Morphology - Severely Coiled Tails / Dag Defect

A
  • Sperm with the dag defect have a severely coiled tail due to midpiece developmental abnormalities.
  • Normally this defect is only seen in small numbers along with other sperm defects associated with disturbances of spermatogenesis. If present in a high percentage as a sole defect it is likely to be of genetic origin.
45
Q

Sperm Morphology - Distal Cytoplasmic Droplets

A
  • Cytoplasmic droplets are normally shed from the distal midpiece position at the time of ejaculation when the sperm mix with seminal fluids therefore the presence of large numbers of sperm with distal droplets may indicate some abnormality of seminal fluids or ejaculation.
  • Sperm with distal droplets should probably be counted as normal sperm during morphology counts as there is no evidence that they are associated with reduction in fertilising capacity.
46
Q

Sperm Morphology - Nuclear Vacuoles

A
  • Nuclear vacuoles can be seen in several forms. Small vacuoles arranged in a row along the equatorial region of the nucleus are know as “diadem defect”. These can be hard to visualise with eosin-nigrosin smears and are more easily identified using phase contrast preparations.
  • Larger confluent vacuoles are much easier to identify.
  • These should be considered an uncompensatable
    defect and likely to have a significant effect on fertility if
    present at > 20% in spermiogram.
  • Semen samples from bulls with this defect may have
    good motility as sperm are live and progressively motile
47
Q

Foreign Cells - Epithelial Cells

A
  • normal when present in small numbers but large numbers may indicate inflammation of the accessory sex glands or urethra.
48
Q

Foreign Cells - WBCs

A
  • Leucocytes may be seen in numbers in cases of vesiculitis or infection of other accessory glands.
  • Normal semen should not contain more than occasional leucocytes however if the sample is not collected directly from the tip of the erect penis but from the opening of the sheath then they may be contaminants.
  • In cases of chronic severe vesiculitis the white cells may be clumped together in large numbers and noted grossly as pus in the sample at the time of collection
49
Q

Foreign Cells - Bacteria

A
  • May be present in significant numbers in semen samples from bulls with infection of accessory sex glands or may simply be contaminants
50
Q

Foreign Cells - Spheroids

A
  • Spermatogenic epithelial cells that have been shed from the seminiferous tubules and their presence may indicate testicular pathology such as degeneration or hypoplasia
51
Q

Results of Semen Analysis - Satisfactory if:

A
  • Progressive motility of >60%
  • Normal sperm morphology
    count of >70%
  • Absence of significant numbers
    of foreign cells such as leucocytes
52
Q

Pathogenesis of abnormal sperm production - stress

A
  • pain
  • hunger
  • cold
53
Q

Pathogenesis of abnormal sperm production - heat

A
  • obesity
  • scrotal abnormality
  • climate
  • fever

Increased temperature -> increased % of defects of the sperm

54
Q

Pathogenesis of abnormal sperm production - season

A
  • photoperiod
  • nutrition
  • temperature
55
Q

Pathogenesis of abnormal sperm production - hereditary

A
  • sperm defects
  • testis size
56
Q

Pathogenesis of abnormal sperm production - puberty

A
  • resembles disturbed spermatogenesis
57
Q

Pathogenesis of abnormal sperm production - toxicity

A
  • zearalenone (mycotoxin)
  • bacterial toxins
58
Q

Pathogenesis of abnormal sperm production - nutritional

A
  • protein
  • vitamin a
  • selenium deficiency
59
Q

Hormonal regulation of spermatogenesis

A

Sperm production:
* Testosterone dependent
* Testosterone is reduced by: stress, cortisol, dexamethasone, exogenous oestrogen

60
Q

Principles and constraints of semen sexing

A
  • Fluorescent dye binds the DNA and allows the heavier X chromosomes to be differentiated from the Y and thus assigned a different charge.
  • The sperm are then defected accordingly into separate pots (Flow Cytometry)

Pro: No unwanted bull calves in dairy farms

Con: Lower conception rates to sexed semen? The evidence on this is very unclear, and the rates of difference have reduced over recent years.

61
Q

Assisted reproductive techniques

A
  • AI
62
Q

Artificial insemination

A
  • Trans-cervical catheterisation in cow * Content
  • Laproscopic intra-uterine insemination in sheep
  • Good fertility rates if done well.
  • Can be comparable to natural service.
  • Many farmers are able to AI cattle themselves, but must be trained and accredited by a Defra approved course

Y4 Farm Reproduction (11 decks)

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