Select Sires

Sex Selected Semen (Part Two)
Transcript of Select Sires' Reproductive Moment Program
on DairyLine Radio Which Aired June 2, 2005
With Ray Nebel,
Extension Specialist and Professor of Reproductive Management,
Virginia Tech

Ray, last week we kicked off our discussion about the flow-sorting technology of selected semen, and we talked about the cost and limitations. But, really, this is a key innovation, isn’t it, for dairy producers?

Oh, definitely, especially in today’s dairy industry. A bred heifer can easily cost $2,000. A female calf born today costs $500. With mad cow disease, and closing of the Canadian borders, there are about 16,000 to 20,000 heifers every year that normally come down from Canada to supplement the U.S. Dairy industry that haven’t been coming down. We are really getting short on replacement females. This technology is a way for dairymen to really stack the deck, you might say, in their favor. Instead of getting the 50/50 male/female it comes out to 90 percent heifers, 10 percent bulls.

The use of sexed semen is requiring a breeding gun very similar to the other methods.

Yes, the straws are 1/4 ml instead of 1/2 ml. What that means, if you are not familiar with breeding cows, is that they are about the same length, but a lot smaller in diameter. There is a universal gun that can take either the 1/2-ml or 1/4-ml straws. All the semen that is shipped internationally is put into 1/4-ml straws. I think that is one reason that all the sex-sorted semen is in 1/4-ml straws. If you are not using the 1/4-ml straws now, you will need to obtain the breeding guns for the 1/4-ml straws.

The thawing recommendations are the same?

Yes. A lot of the keys to success would be the same for the 1/4 ml or the 1/2 ml, and the thawing recommendation is the standard that we recommend for the 1/2-cc straws(*), which is: 95 degrees Fahrenheit water bath for 45 seconds. The semen-thawing and -handling environment should be warm and draft free. The other similar recommendation is in how the semen is handled, as far as warming of the insemination equipment, the sheathes, the paper towels. All of that would be the same. We would handle it as optimally as we do for 1/2 ml. We want to do all those procedures as best we can.

Is this ready for the market, do you think?

Well, the question has become, "Is the market ready for sexed semen?" or "Is the semen ready for the market?". One of the big concerns or recommendations, because we are going with 2 million sperm instead of the standard 15 to 20, is that sexed semen be used for heifers only, not for lactating cows. Research has shown that there is a slight reduction in conception rate. Normally, in virgin heifers, we would expect somewhere between a 60 to 75 percent conception rate with the standard 15 to 20 million sperm. Research with sexed semen has shown somewhere between 50 to 60 percent. There is going to be a reduction of fertility. However, in the virgin heifers we still can get acceptable pregnancy rates. Sexed semen is not being recommended for lactating cows, even though we know some people are going to push the envelope. It is not being recommended for lactating cows because of the concern with reduced conception rates.

There is more to talk about, this is a discussion of Sex-Selected Semen. We will do that next week with Ray Nebel, Extension Specialist and Professor of Reproductive Management at Virginia Tech.

(*) One milliliter (ml) is the same as one cubic centimeter (cc).

Select Sires Inc., 11740 U.S. 42 North, Plain City, Ohio 43064 / Phone: (614) 873-4683 Fax: (614) 873-5751