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♦ Manufacturing at its Finest
♦ Manufacturing at its Finest

Semen production in the bull is a dynamic process. The bull basically has a sperm factory that never takes a break. It constantly produces sperm 24 hours a day, seven days a week, throughout the year. It does not take time off for holidays or bad weather, although weather can impact how the factory performs. So can a bull's health, his body condition, nutritional status, age and his environment.

The "assembly line" production process takes about 10 weeks to produce a sperm capable of fertilizing an egg. It's a complex process in which cells divide to reduce their chromosomes (amount of DNA) by half, dramatically change their shape and grow a tail capable of motion. Any imperfection in the process, such as breaks in the strands of DNA, results in a defective sperm that won't be fertile.

Climate Control
The thermostat in the factory is set to maintain the temperature at 4 degrees below body temperature. If the factory runs hotter than this, defective sperm is the result. To help ensure quality sperm, males are equipped with a sophisticated "air conditioner" that works to maintain the proper temperature. Features of that air conditioner include a large number of sweat glands along the surface of the bull's scrotum, the ability to raise or lower the factory depending on the outside temperature and a system where warm arteriole blood coming from the body is cooled at the top of the scrotum by cooler blood returning from the testis. In over-conditioned bulls, fat deposits in the top of the scrotum interfere with this cooling mechanism and result in a factory that is too warm. Bulls that are over-conditioned, as is the case with some beef bulls when they first arrive at GENEX, will tend to produce semen with a higher number of defective sperm. For many of those beef bulls, it is a balancing act between the animal "looking good" and producing good quality semen.

Of course, things such as hot summer temperatures or illness with fever can overwhelm the factory's cooling capacity and result in defective sperm too. Even brief thermal insults lasting only a few days can impair normal semen production for several months. A bull with "good quality" semen one day can have a change in quality the following day. That is why the GENEX laboratory staff examines each and every collection that arrives in the laboratory in numerous ways.

Screening for Fatal Flaws
Sperm need to be able to swim, have an adequate energy supply, be able to move up through the uterus into the oviduct, attach to the lining of the oviduct and wait for a signal from the female that her ova will be passing by soon. Then, the sperm needs to have enough energy to pull away from the lining of the oviduct by becoming hyper-motile, possess the necessary membrane structure that can attach to the ova and have the enzymes necessary to digest its way through the covering of the egg. Finally, the sperm needs to have the right complement of DNA that will combine with the ova's DNA to create an embryo. Once inside, its DNA must be fully functional and not have any lethal genetic defects.

Every bull will produce some sperm that have flaws. Some sperm can't swim. Some don't have adequate energy stored. Some have faulty membranes, and some don't have properly packaged DNA. Any one of these flaws causes that individual sperm to be useless. However, as long as enough of the entire population has the necessary traits, a bull's semen will be fertile when deposited at the right time and the right place in a female's reproductive tract.

Collectively these necessary physical characteristics of a population of sperm are referred to as "semen quality." Each collection arriving in a GENEX laboratory is screened to ensure it has sufficient numbers of sperm with those quality characteristics. If an ejaculate does not have adequate quality, it ends up in the dumpster. In 2016, GENEX laboratory staff evaluated the physical characteristics of over 51,000 ejaculates collected from 615 GENEX bulls. Of these, approximately 6,500 ejaculates ended up in the trash after the initial screening because the population of cells in the ejaculate had too many defects.

Production Protocols
Those collections that pass the initial screening tests are allowed to proceed to the next steps in the GENEX production process: adding preservation media and freezing. Following the protocols precisely for preservation and freezing is important in order to yield an adequate number of normal sperm per straw after freezing.

Protocols are also important because each part of the process can influence others, even the preservation media and the method by which it is added to the semen, the precise ratio of semen to extension media, the rate of temperature change of the extended semen to 40 degrees (F), the period of time the semen spends at 40 degrees, and the rate of temperature change between 40 degrees and liquid nitrogen temperature.

Quality Control Commitment
As for production protocols, from the time a bull leaves his stall to go to the collection arena until his semen comes out of the freezer, no less than 56 distinct steps are carefully carried out and monitored. Throughout the process, staff work by the motto, "If there's any doubt, throw it out."

That motto and the laboratory staff's work doesn't end when the semen is frozen in liquid nitrogen. Instead, straws from each batch are then thawed and again inspected in the laboratory to ensure an adequate number of quality sperm survived the freezing process. Demonstrating the cooperative's commitment to quality, in 2016 1.5 million straws went in to the dumpster after failing this inspection.

Meeting Members' Expectations
In total, in 2016 staff collected enough sperm from GENEX bulls to make approximately 18 million straws of semen. Of that, enough semen to make 7.5 million straws ended up in the dumpster because the sperm did not have the right physical traits to live up to the cooperative's values of quality and integrity.

The GENEX production and laboratory staff's commitment is an important reason the cooperative is the trusted provider of world-class animal genetics.

September 2016