CAL: Semen evaluation

Question 1

Outline method for electroejaculation (EEJ)

Answer 1

The 3 electrodes on the probe should face ventrally in the rectum. Voltage can be controlled using a battery pack. The voltage should be started off low and slowly increase it as the bull becomes accustomed to it. The current should be given in an on/off system. Faeces should be removed prior to insertion of probe and the accessory sex glands should be gently stimulated. Cover the probe in lube. Initial fluid is from accessory sex glands and should not be collected. Collect semen into a pre-warmed container. Ejaculate volume of bulls tends to be 2-8ml.

Question 2

How is manual stimulation to ejaculation performed?

Answer 2

penile stimulation (dogs, pigs) or ampulla massage (bulls)

Question 3

Name 4 methods for collecting semen

Answer 3

Artificial vagina (AV)
Electroejaculation (EEJ)
Manual stimulation
Collection from female vagina after natural service

Question 4

What should you initially look at the ejaculate for?

Answer 4

presence of pus, blood, urine, contamination. Concentration can be estimated depending on whether the sample is creamy, milky, cloudy or watery

Question 5

Outline the scoring system for semen concentration

Answer 5

• 5= thick creamy consistency and colour, contains >5000 million sperm/ml.
• Creamy samples score 4 and contain about 4000 million sperm/ml.
• Thin creamy samples score 3 and contain roughly 3000 million sperm/ml.
• Milky semen scores 2 and contains approximately 2000 million sperm/ml.
• Cloudy water appearance scores 1, normally this would be discarded.
• Clear watery sample scores 0, contains mainly plasma and has few sperm at best.

Sperm concentration can also be assessed quantitatively by diluting with formal saline and then counting in a haemocytometer.

Question 6

What % sperm motility should you aim for?

Answer 6

Sperm motility is an important parameter to assess but note that it can be artificially reduced by e.g. cold or heat shock, water in collecting tube, delay between collection and evaluation etc. Because of this it is the most ‘lenient’ criteria - for breeding soundness exams in bulls North America a minimum of 30% forward motility is required.

Question 7

Outline the wave motion scoring system

Answer 7

Range of 0 (dead) to 5 (very good)
5 = VERY GOOD = dense, rapidly moving, 90% + sperm active.
4 = GOOD = vigorous moving waves but less rapid = 70-80% motile
3 = FAIR = small, slow moving waves, fresh AI only, 45-65%
2 = POOR = no waves, some sperm movement, 20-40% active. Discard
1 = VERY POOR = very few spermatozoa show signs of life. Discard.
0 = DEAD = all sperm are motionless. Discard.

Question 8

What stain is often used to assess sperm morphology?

Answer 8

Eosin-Nigrosin.

Examine using oil immersion at x1000 magnification.

Question 9

What semen parameters should ALWAYS be evaluated?

Answer 9

Gross appearance
Concentration based on colour
Motility
Morphology

Question 10

Which parameters shouldn’t always be evaluated?

Answer 10

Concentration counted in a haemocytometer
Bacterial culture
WBC evaluation

Question 11

Generally, how are animals classified after a repro soundness exam?

Answer 11

• Satisfactory (or sound) – all is good
• Deferred (or temporarily unsound) – there is a temporary problem which can probably be resolved e.g. lameness, scrotal mange; the animal should be re-evaluated after a period of time
• Unsatisfactory (or unsound) – non resolvable problem