You will often hear us talk about ‘reference values’, these are the minimum optimum figures that we want to see to have the highest chance of success. For example, in order to have the best chance of pregnancy after natural service a bull will need to have a specific number of sperm cells in the semen.
Here are the comparisons of the reference ranges for Humans and Bulls for fresh (not frozen) semen.
Semen Volume (not much difference here)
Human Semen: 1.4-1.7 ml
Bull Semen: 2-10 ml
Semen Concentration (this is where the differences start)
Human Semen: 12-16 million per ml
Bull Semen: 400-750 million per ml
Total number of sperm in the ejaculate
Human Semen: 33-46 million
Bull Semen: 800-7500 (7.5 billion) million
Abnormalities (big difference here)
Human Semen: 4% of the sperm need to have a normal appearance
Bull Semen: 70% need to have a normal appearance
Human Semen: 38-42% of the sperm in the sample need to be swimming.
Bull Semen: 60-79% motile
*Please note that for comparison purposes we have used the ‘Good ranges’ for the bull semen. Figures below the ranges in both humans and bulls will not necessarily result in zero success, the chances just may be reduced.
Bull Breeding Soundness (Third Edition), Albert D. Barth 2013
WHO laboratory manual for the Examination and processing of human semen, Fifth Edition 2010