sex

[Anonymous]

I have had eight calves so far this year and each one is a heifer. The first 3 were AI from the same bull. The next 5 were from a young bull I purchased last Fall. Is there a tendency for a bull to throw calves of the same sex. The probability of this being a chance event is extremely small.

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[Anonymous]

My first 12 calves this fall included 9 single heifers and the twin heifers. One bull so far. These represent 4 AI sires and 2 pasture bulls. Some years go that way. They say you are more likely to get a heifer if you breed early and a bull if you breed late. Last year we had too many bulls so we moved up our breeding time (we breed while she is standing rather than when she is done.) I guess when a herd bull is first turned out he may be a little anxious and breed earlier too.

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[Anonymous]

Some folks around here honestly belive that if the cow is facing east when she gets bred you get bull, west a heifer. North and south doesn't matter. Some years we get almost all heifers or bulls, but over the years it works out to right at 50/50, give or take a bit.

dunmovin farms

> My first 12 calves this fall
> included 9 single heifers and the
> twin heifers. One bull so far.
> These represent 4 AI sires and 2
> pasture bulls. Some years go that
> way. They say you are more likely
> to get a heifer if you breed early
> and a bull if you breed late. Last
> year we had too many bulls so we
> moved up our breeding time (we
> breed while she is standing rather
> than when she is done.) I guess
> when a herd bull is first turned
> out he may be a little anxious and
> breed earlier too.

 

[Anonymous]

The info on breeding early for heifers or late for bulls comes from University studies and has been comfirmed in equine reproduction also. It has to do with which sex of sperm swim faster and therefore the timing on which ones will be in the proper place when the egg gets there. The studies show that you can get about 65% females breeding early.

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[Anonymous]

I'm aware of that. I didn't know that a university had finally gotten around to studying it though. Those of us that have been doing AI for 20 plus years have known about it after very few years. When they started sexing semen was when I figured out why.

dunmovin farms

> The info on breeding early for
> heifers or late for bulls comes
> from University studies and has
> been comfirmed in equine
> reproduction also. It has to do
> with which sex of sperm swim
> faster and therefore the timing on
> which ones will be in the proper
> place when the egg gets there. The
> studies show that you can get
> about 65% females breeding early.

 

[Anonymous]

Just making sure I have the right idea... because the Y chromosome is for males and the X is for females, the male sprem would get there ahead of the females, because they weight that much less than the female right? the male sprem would die out, then the female sprem would get there at the right time and be able to feritlize the egg right?

Jane

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[Anonymous]

You have the theory right, but don't think there's any scientific proof that it works. We breed 8-12 hours after standing heat and get about a 50-50 ratio over time. Some years more bulls, some years more heifers. Here's a link to the Select Sires site that has an article about timing AI:

<A HREF="http://www.selectsires.com/growingpains5.html" TARGET="_blank">http://www.selectsires.com/growingpains5.html</A>

The article says "Over the years, numerous methods have been suggested to alter the sex ratio of offspring. One of the most common is based on the notion that male sperm swim faster than female, but they die sooner. Thus, if you inseminate early, the male sperm die resulting in more heifer sperm fertilizing the eggs. To my knowledge, there is no conclusive, repeatable data to support the idea that male and female sperm vary in either swimming speed or longevity."

Good luck....



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[Anonymous]

Male sperm swimming faster then female is the principle behind sexed semen. The last I saw on it, the placed semen in a container with a permiable membrane dividing it in have from top to bottom. The semen was put in one side and the other side of the container was "excited" to attract the sperm. I don;t know how, maybe dirty movies or a six pack of beer. Anyway, after a period of time the sperm is drawn from each side of the container, that on the original side is mostly female, the other side is mostly male.

dunmovin farms

> You have the theory right, but
> don't think there's any scientific
> proof that it works. We breed 8-12
> hours after standing heat and get
> about a 50-50 ratio over time.
> Some years more bulls, some years
> more heifers. Here's a link to the
> Select Sires site that has an
> article about timing AI:

>
> <A HREF="http://www.selectsires.com/growingpains5.html" TARGET="_blank">http://www.selectsires.com/growingpains5.html</A>
> The article says "Over the
> years, numerous methods have been
> suggested to alter the sex ratio
> of offspring. One of the most
> common is based on the notion that
> male sperm swim faster than
> female, but they die sooner. Thus,
> if you inseminate early, the male
> sperm die resulting in more heifer
> sperm fertilizing the eggs. To my
> knowledge, there is no conclusive,
> repeatable data to support the
> idea that male and female sperm
> vary in either swimming speed or
> longevity."

> Good luck....