Bull throwing high percentage of heifer calves

I was told if you want male offspring you have to leave it in longer "to make the tail".
HTH

Kidds said:

I was told if you want male offspring you have to leave it in longer "to make the tail".

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Is that the theory you tell your wife?

@charleyman39 yes finally someone who believes it.
I had a homebred 7/8 AA black bull. He threw 75%+ heifer calves, almost always RED, out of my hodgepodge of BLACK 3/4 AA cows mostly conceived themselves by a range of Genus AA semen; plus one Grey SimxAA cow who consistently had red heifer calves.
I can hardly remember a bull calf from him, they were so few.

Kidds said:

I was told if you want male offspring you have to leave it in longer "to make the tail".
HTH

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You are actually correct-ish. Male sperm can have weaker tails and are sensitive to high alkaline? pH. Also vaginal mucus consistency matters - I had a friend who didn't get pregnant until she had a cold and was taking cough syrup, which thins mucus . . . everywhere . So shortening the arduous journey actually can help.

You can also get genetic sperm production problems where one sex of the sperm is not formed properly. Hence the odd family with many children of the same sex.

charleyman39 said:

Has anyone ever had a bull who throws 75% heifers before? This is his second crop of calves. Last year I had 12 bull calves and 29 heifers. So far this year, 2 bull calves and 16 heifers. In his first year I was happy enough to put it down to chance and maybe the fact he's a young bull so perhaps not getting them early in heat. This year though, he's a big animal now and was on them right away. Never had anything like this before. Wouldn't mind so much if they'd be viable replacement heifers but he's a charolais so not exactly ideal, for me anyway.

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This is definitely a 'thing' & more likely a mutation if it happens regularly.
It may well be something as simplistic as time of service.

There seems to be an increase in this trait within some of the breeds if you look at the amount of heifers being produced by the larger pedigree breeders who all use AI etc to obtain/reduce specific traits & breed the ideal animal.
With the introduction of sexed semen how is this affecting the subsequent generations breeding statistics?
Is your bull a full traceable pedigree, (on paper) if so was he or his parents or grand parents got by A.I?
If so you should know where they were raised based on Prefix

Another thing to think about
The amount of female hormone products in human sewage is significant & is already affecting other life cycles.
Where is that in the cycle of grazing animals here in the U.K.

Wouldn't that depend on what the pedigree breeder is actually registering? Maybe someone breeding maternal for the female market wouldn't necessarily register the bull calves and just put them off store?

The breeders I had in mind are all predominantly 'Sale Bull' breeders though you may very well be correct.

ladycrofter said:

You are actually correct-ish. Male sperm can have weaker tails and are sensitive to high alkaline? pH. Also vaginal mucus consistency matters - I had a friend who didn't get pregnant until she had a cold and was taking cough syrup, which thins mucus . . . everywhere . So shortening the arduous journey actually can help.

You can also get genetic sperm production problems where one sex of the sperm is not formed properly. Hence the odd family with many children of the same sex.

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ladycrofter, you have identified a major cause of xy : xx sperm number discrepancy being mucus pH. However slight this pH shift is, the consequences in foetal gender can be great. Mucus thickness varies with pH and naturally between individuals and timing in the oestrus cycle. There is probably a heap of environmental factors causing these changes that can affect a herd or a flock at any time, or consistently most seasons if management is also consistent.

To prove a bull's genetics is not the cause of leaving a predominance of one gender, the bull would need to be mated elsewhere where the environment is different. If still happening, then DNA analysis undertaken to see if there is a distinct difference on key alleles on the appropriate chromosome. Once needle in a haystack stuff, but now easier with extensive gene mapping. I doubt that such tools are worth developing to see if there is a value proposition in having such sires, especially in light of sexed semen availability. But having a test to eliminate such sires if the less desired gender offspring predominate may be useful especially if it is found more frequently in a certain breed/strain.


Sperm travel up between mucus strands. These are secreted the whole length of the female reproductive tract and through the "choke point" of the convoluted cervix. Here especially things can get difficult if the mucus strands get disrupted and broken up causing the sperm to swim in confused directions, as seen in ewes fed on high intakes of Red Clover cultivars containing high levels of oestrogen. Make no assumptions that its an easy exercise to get a successful pregnancy. The winning sperm cell and the resulting embryo have many tests to pass before a successful embryo becomes a viable foetus before we even talk of birth challenges.

Would an AM and PM AI service of conventional semen have any bearing on the sex if a pregnancy?

AI should have no effect on the sex of the pregnancy, unless of course sexed semen is being used. The semen gets put straight in to the uterus and apparently a good tech can put a wee shot in either horn (not me !)
As @Global ovine said, it is a torturous journey through the sticky folds of the cervix and it's a wonder anything gets through. Hence ejecting semen before the cervix would drastically reduce conception rates. One straw has so few sperm cells compared to multiple mounts by a bull. And sexed semen even less, the 50% male e.g. is removed but not replaced with more female. (Maybe you can pay extra for a "double" straw now?)

Northeastfarmer said:

It was just 2 payments wasn’t it.
when you’d claimed 1 it went to blue,
When you’d claimed both it went to red…

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And a maximum of 90 per holding number each year.

Northeastfarmer said:

Is that the theory you tell your wife?

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No, it was her that told me but it might have been a trick.