6. Collection and Preparing of Semen of the Bull. Macroscopic Examination of the Ejaculate

What is the purpose of the artificial vagina (AV) in semen collection from bulls?

The AV is an imitation of the cow's vagina and provides thermal and mechanical stimulation to the erect penis, leading to ejaculation.

How is the AV prepared for semen collection?

Warm water is poured through the filling aperture to raise the lumen temperature. Sterile lubricant is applied to the inner surface. Before ejaculation, the AV is cooled to the appropriate temperature.

What is the recommended temperature range for the AV before ejaculation?

The AV should be cooled to 38-40°C before ejaculation.

How is semen collected using the AV?

The bull is released into a collection cage, and the operator, located at the right side of the bull, holds the open end of the AV towards the ground. The bull is teased, and when mounting occurs, the operator directs the prepuce into the AV. Ejaculation occurs into the extension cone.

What is rectal massage in semen collection?

Rectal massage involves the introduction of a lubricated hand and arm into the bull's rectum to locate the seminal vesicles. Stroking them against the pubis causes accessory fluid to drip.

What is the disadvantage of using rectal massage for semen collection?

The samples obtained through rectal massage are not representative of the true ejaculate, and the sperm count is low.

How does electrical stimulation aid in semen collection?

Electrical stimulation can be used in young bulls. It involves holding finger rings or a probe over the ampullae and applying varying levels of electrical stimulation. Lower voltage stimulates the discharge of accessory glands, while higher voltage leads to the dripping of the sperm-rich fraction.

What does macroscopic examination of semen focus on?

Macroscopic examination focuses on the overall appearance of the semen sample, including its volume, sperm-cell concentration, and motility.

How is pH examined in semen samples?

pH is measured using pH indicator sticks or a pH meter. In fresh semen samples, the pH should be slightly acidic, ranging from 6.6 to 6.9.

What does a pink-red colour in bull semen indicate?

A pink-red colour may indicate the presence of blood due to injury.

What does a grey/brown colour in bull semen indicate?

infection

What does a light brown colour in bull semen indicate?

faeces

What does a light yellow colour in bull semen indicate?

riboflavin

How is semen volume assessed during macroscopic examination?

Semen volume can be assessed using a calibrated collection glass or a pipette. The average volume of semen varies between 3.5 and 6 ml.

What does normal semen smell like?

resembles fresh milk

What does a putrid odour in semen indicate?

A putrid odour may indicate an inflammatory process in the vesicular gland.

What does the presence of urine odour in semen suggest?

The presence of urine odour suggests the presence of urine contamination in the semen.