Ram infertility Flashcards
What age in rams is the onset of puberty & sexual maturity?
Puberty = 6mo
Sexual maturity = 12mo
What factors may affect ram fertility?
Age - onset & senescence of fertility
Season (short day breeders)
Social interactions/rearing
Environmental pollution
Pastures (E2, Pb, As)
Presence of predators
Nutrition/BCS/b.w.
Management factors
What management factors may affect fertility/conception rates?
Time of joining - seasonality etc.
Length of joining - 2 cycles/35 days
Handling at mating - shearing, stress
M:F ratios (1:100)
Semen handling/AI technique
What aspects of a general physical exam should be considered in a ram BSE?
Examination of animal at rest & moving
BCS
Vitals - TPR, MM, CRT etc.
Structural soundness (MSK exam)
Outline the key points of a physical exam of a ram’s reproductive organs during a BSE
Penis/prepuce: observe, palpate, manipulate
- exteriorise the penis to examine shaft/glans/urethral process
Scrotum/testes: observe, palpate
- scrotal skin thickness » thermoregulatory compromise
- scrotal circumference » sperm output
- testicular consistency (firmness/resilience)
- head/body/tail of the epididymis
What measures of testicular size are available for use in rams?
What are normal values for these measures in a sound breeding ram?
Testicular weight (g) / kg b.w.
Scrotal circumference
- 12mo ram ≥ 30cm
- 24mo ram ≥ 34 cm
What methods of collection of semen are available in the ram?
Electroejaculation (via rectal probe)
Artificial vagina
What characteristics of semen are assessed in an in-field & laboratory semen examination?
In field exam:
Gross exam: volume + concentration
Low power microscopy: wave motion/mass activity (rapid swirling waves)
Phase contrast microscopy (400x): motility (% actively moving forward)
Lab exam:
Nigrosin-eosin stained smear → % live/dead spermatozoa + morphology of head/midpiece/tail
What is the minimum acceptable values for sperm motility (% actively moving forward) + normal morphology (% no abnormalities)?
Motility ≥ 30%
Morphology ≥ 70% normal sperm
List some examples of morphological abnormalities of the head + midpiece/tail of sperm?
head: narrow, narrow at base, pyriform, abaxial
midpiece/tail: proximal/distal droplet, tailless heads, singly bent tails, coubly bent tails, coiled tails
What are some clinical signs of testicular hypoplasia in a ram?
Small testes (circumference <30cm)
Poor consistency (soft/poor elasticity)
Low semen concentration on total sperm count
Low motility %
Abnormal midpiece/tail morphology
What are some causes of congenital testicular hypoplasia in a ram?
Cryptorchidism
Chromosomal abnormality (XXY)
Embryological hormonal imbalance
Segmental aplasia of the mesonephric duct (→ blockage of sperm transport from testes onward)
Inguinal hernia
What are some causes of acquired testicular hypoplasia in a ram?
Poor nutrition during development
Parasitism (Chorioptes bovis) during development
what are some clinical signs of testicular degeneration in both the early/mild stage, severe stage & end-stage?
Mild stage: decreased sperm production
Severe stage: decreased scrotal circumference, soft/pliable consistency, shrunken epididymal tail, decreased sperm production/concentration
End stage: testicular fibrosis (firmness, small, no resilience) + epididymal tail firmness/empty
What are some causes of testicular degeneration?
Infectious causes:
- Chorioptes bovis dermatitis (thick scrotal skin)
- Orchitis/epididymitis (B. ovis)
- Actinobacillosis (A. seminis)
- Histophilus ovis
Non-infectious causes:
- general inflammation/pyrexia
- wool-covered scrotum (show rams)
