Semen and Semen Technology

Semen consists of spermatozoa suspended in the fluid secretions of the male accessory sex organs. The fluid portion of semen (seminal plasma) functions as a transport medium for the spermatozoa, and it contains a variety of substances including various electrolytes, fruc­tose, citric acid, and sorbitol.

Semen is collected and evaluated as part of protocols to evaluate the fertility of breeding males, but no single characteristic of semen or spermatozoa is accepted as a perfect gold stan­dard for predicting the fertility of a given sample of semen. Some characteristics of semen that are evaluated and appear to have some correla­tion with potential fertility when considered together are (1) concentration of spermatozoa per milliliter of semen, (2) motility characteris­tics of spermatozoa, and (3) shape of the sper­matozoa. The concentrations of spermatozoa per milliliter vary among species, and this should be considered when evaluating semen.

Semen is also collected and used for breed­ing technologies such as artificial insemination and in vitro fertilization. one ejaculate of a bull can be divided into as many as 500 portions, and if properly handled, each portion can result in conception. In fact, more than 30,000 cows can be bred each year with the semen collected from one bull. semen can also be frozen and stored for years.

The division of a semen sample into multiple portions and the freezing of semen for long­term storage require the addition of solutions to increase the volume of the sample and protect the spermatozoa during freezing. interestingly, the characteristics and composition of the most effective solutions vary with semen samples from different species. This suggests that sper­matozoa from different species have unique metabolic andIor structural differences.