Technical information - selection

Importance of Good Quality Semen in Artificial Breeding Programs


Contributed by Dr Graham Stabler Director & Collection Centre Manager (Etna Creek) Beef Breeding Services

It is extremely disappointing and frustrating to have embarked in an AI, ET or IVF program only to achieve poor results.

There are several factors that may contribute to the failure of such a program including seasonal conditions, drought, nutrition, technical problems and semen quality.

Research has established that the use of semen below certain minimum standards is more likely to result in an unsatisfactory outcome. This does not mean that a particular bull will not achieve satisfactory results with natural mating, however if the batch of semen being used in a program is of lower quality, results may be poor. This can be very disappointing and costly in terms of time, drugs for synchronisation, labour and personal stress.

Progressive motility is the most commonly used criteria for presale semen testing and is usually included in supplementary sheets (along with EBV, EMA, weight etc) given to buyers on sale day. Progressive Motility alone does not give a good enough indication of semen quality for use in Artificial Breeding Programs

Semen is often rated using two numbers (eg 40/45). The first value given (40) represents the percentage of Post Thaw sperm that are alive and the second value (45) represents the percentage of those alive sperm that are swimming normally.

Our minimum for motility are 35/35 for domestic semen and 40/40 for export semen. We now have a CASA system (Computer Assisted Sperm Assessment) which provides a signal percentage for motility and eliminates the “Human Factor” on this assessment.

Concentration of semen is also important. We aim to provide 25 million sperm in each 1/4ml straw and of those we expect to have no fewer than 8 million live normal sperm available on insemination.

Motility rating does not take all of the abnormal sperm into account (eg sperm with proximal droplets and sperm with vacuoles will appear to swim normally but will not result in a successful pregnancy). The higher the percentage of these defects, the lower the chance of a normal sperm reaching the egg and fertilising.

The detailed examination of semen to evaluate the percentage of abnormalities is known as Morphology. This should be done with a microscope capable of 1000 times magnification.

We are often asked to examine straws from batches which have produced poor results in an artificial breeding program, we frequently find defects in morphology which would not be obvious with just a Motility assessment or examination with a low powered microscope.

My recommendation is that, if the semen you are planning to use does not have a “Post Thaw” assessment available, you should have Morphology, Motility and Concentration done before you begin your program. We can do this for you.

Failures in AI, ET and IVF programs are preventable. There are enough other factors that may affect your success. Semen Quality does not have to be one of them!