Bull Sperm Morphology Testing Explained

What is Bull Sperm Morphology Testing?

A small drop of semen is added to a vial of formal saline crush side. This is sent to the laboratory where it is examined under a large high-powered microscope that can examine the head and tail of the sperm in detail.

Why is Bull Sperm Morphology important?

Bull sperm morphology is the trait most strongly correlated with calf output. Even if the sperm can swim up to the egg, if the sperm head is defective no calf will result.

The sperm sample is essentially a biopsy of what has occurred in the reproductive tract with the morphology test permitting insight into the functional capacity of the testis and epididymis.

How does Sperm Morphology Testing work?

Sperm morphology results are reported as the percentage of sperm that appear normal. There are also 7 categories of abnormality reported.

Why are there different categories of abnormal sperm?

The 7 different categories of sperm abnormality are listed in the current Australian Cattle Veterinarians (ACV) system (McAuliffe, Johnston, Perry 2010). This system was developed by Dr Viv Perry and aids the prognosis of the bull: recovery from some categories is more rapid than from others (Fordyce et al 2006).

What happens if your bulls have a poor result?

It is recommended that the bull is retested. Generally after 10 weeks to allow a full spermatogenic cycle and passage through the tract. However, this can be done earlier if the abnormalities recorded dictate this.

How is semen obtained?

The semen sample is collected either by manual palpation, electro-ejaculation or by AV.


Fordyce, G. et al. 2006. Standardising bull breeding soundness evaluations and reporting in Australia. Theriogenology 66: 1140-1148.

McAuliffe, P., Johnston, H., Johnston, P., and Perry, V. (2010) ‘Electroejaculators, Morphology and Microscopes.’ (The Australian Cattle Veterinarians: Eight Mile Plains, Qld)