I hope the stork brings a girl.

In the last post, we talked about A.I. and its benefits to the dairy industry. Today, we'll add another piece to the puzzle and discuss sexed semen, which can lead to a greater possibility of female offspring.

First, here's an important sidenote: only girl cows can produce milk. I'm sure that just completely changed the way you think about nature. :) Therefore, for a dairy farm, cows are the queens. Heifers, or females that haven't calved yet, are princesses. The profitability of a dairy farm relies on females' milk production. When a cow gives birth to a female, that female calf will likely eventually end up giving milk herself.

To increase the odds of having a female offspring, many farmers choose to artificially inseminate with sexed semen. This technology was developed in 1989 by scientists with the United States Department of Agriculture, and it has been readily available since the early 1990's.

So, just how can you sort something you can't even see? Well, scientists inject a dye into the sperm collection. It's fluorescent, and it sticks to the DNA in an amount proportional to the number of X and Y chromosomes in the sperm. X chromosomes (females) contain more DNA than Y chromosomes (males), so more dye sticks to the sperm cells that are carrying female chromosomes.

Next, the sperm cells are sorted. A laser lights up the dye, and the sperm gives off light proportional to its DNA content. The X sperm always glowers brighter, because it's carrying more DNA. The sperm is sorted into two different batches, allowing it to be packaged into doses according to the probable sex of offspring it will produce.

Species from cattle to rabbits to sheep to pigs have benefitted from this technology. On our farm, sexed semen has allowed us to produce more heifer offspring, which will enter our herd and eventually produce milk. It has increased our efficiency and allowed for a consistent supply of heifers. Does the stork really have anything to do with it? No. Science? Absolutely.

Let's Talk About Sex...

...Cow sex that is.

Now that I have your attention, we're going to talk about artificial insemination in the dairy industry. Before we do, here's a new addition on the farm. Pepsi delivered a healthy female calf (heifer) on April 10. See our last post to learn more about the mama.

Before the calf was even born, we knew there was a good chance that she would be... well, a she. Pepsi was bred using artificial insemination to Million, a bull owned by Select Sires. The semen was sexed, meaning that there was roughly a 90% probability that the calf would be female. Before we get into those details, let's start with the birds and the bees: how artificial insemination works and why it's used.

The majority of dairy farms in the United States use artificial insemination. Semen is collected from bulls off-site. The semen is stored in sealed straws, which are frozen in liquid nitrogen tanks. One farmer can keep numerous straws of semen stored for an extended period of time in a tank at their farm. As the cows come into estrus, or heat, the farmer can remove the straws, thaw them, and breed the cows. The video below, courtesy of the University of Missouri, explains more about the breeding process.

Artificial insemination accomplishes several purposes in dairy production. First, it provides tons of options for reproduction. A dairy farm that only has one bull to use for natural breeding doesn't have genetic options. On the other hand, a farmer that uses artificial insemination can select a mate for a cow based on genetic potential that will improve the quality of the herd. This selective breeding allows a farmer to select a bull that will be a solid match for the particular cow he is breeding. Secondly, artificial insemination can be a safer alternative than natural breeding. If a farmer is housing a bull on his farm, then he takes the risk of the bull endangering himself and his employees. A full grown bull weigh around 2000 pounds. That's a large critter to contain and move! The bull can also be hard on the cows. The semen for artificial insemination, alternatively, is stored in a tank no larger than a kitchen trash can. Finally, artificial insemination can be very economical. A farm that is using natural breeding would have costs associated with housing the bull, such as feed and medical expenses, but a farm that is using artificial insemination can purchase a dose of semen from a reputable bull starting around $15.

With such benefits, it is no wonder that artificial insemination is so widely used in the U.S. It is a powerful tool that allows farmers to improve their herds while reaping other benefits. Stay tuned for our next blog post for more sex talk (cow sex, that is) and to see how semen can be sexed to lead to a greater possibility of female offspring.