Semen Diluters (Extenders): Importance, Properties, and Types

Semen diluters also known as semen extenders.These are specially formulated solutions used to dilute and preserve semen for artificial insemination. These fluids increase the volume of the ejaculate and provide a supportive environment that helps maintain sperm viability, motility, and fertility during storage, transport, or freezing.

Importance of Semen Dilutors

• Semen dilution increases the volume of the ejaculate so that many cows can be inseminated.
• For the sperm it provides favourable media, protects during cooling and prolongs its life during storage.

Properties of Semen Dilutors

• The diluting fluid must be isotonic. Eg., 2.9% sodium citrate dehydrate.
• Must maintain a near neutral pH favourable for sperm vitality.
• Should have buffering capacity; not of great importance for semen from stallion, boar and dog because of low concentration of spermatozoa, eg., isotonic sodium citrate.
• Should be non-toxic.
• Should contain electrolytes and non-electrolytes at optimum concentration.
• Should provide nutrients for both aerobic and anaerobic metabolic processes. eg., egg yolk.
• Should provide protection against cold shock.
• Should control microbial contaminants. Eg., antibiotics.

The semen dilutors can be categorized into three groups:

1. Ambient Temperature Diluent (18-25°C)
2. Refrigerator Temperature Diluent (4-6°C)
3. Ultralow Temperature Diluent (< 0°C)