What is the highest percentage of one sex of calves out of a herd bull?

[dcbehle]

My son got in the Angus business in 2006 as a 4-H project. We bought a couple of heifers from my wife's uncle in South Dakota and it has been one of the best development tools for building kids/young adults.

Anyway, my son named his operation Noble Farm, because we have "no bulls" to breed with - we AI everything. While the herd has grown, the odds have followed the naming of his operation. In 7 years, we've had 77.7% of our calves come as heifers! All but one was AI'd, the exception was when the neighbor's bull was in our pasture when we got home from the county fair years ago and he kept the one mama happy!

Bottom line is that it has worked out well for us. More heifer calves have allowed us to grow our herd. Moreover, our customer base loves our heifers - while marketing bull calves is more hit and miss. I guess God has always had better plans for us than what we could have dreamed of! And that is no bull, Noble.  (angel)

 

[jwfarms]

While clearly way out there on the curve, I do think there is a biological reason that screws things past 50/50 in either direction.......  I have spent considerable time pondering human families where daughters from girl only families only have daughters and it seems to go that way scewed for a few generations, or in the case of a friend of mine, who had one brother, his dad only had brothers, his grand pa only had brothers and his great grandpa only had brothers.......  So my reasoning.......

Sperm are not identical.  Male sperm are more fragile, swim faster, don't wait as long, and are more subject to non ideal vaginal/uterine conditions.    Female sperm are more durable but don't swim as fast........ 

In humans, I can make a hypothesis that mothers of daughters family trees may perhaps be explained by this.  Perhaps the women have slightly different pH then normal?    It is also why men who smoke or are in smoky places a lot, or have saved on a nuclear sub, or in a nuclear power plant or any other source of environmental pollution tend to have great higher odds to have daughters.......

I have no theory on humans that have family trees weighted to boys, I don't buy my friends theory the
At the men in his family are so manly they don't have girl sperm (though I waited five years for him to tell me he was having a girl to tell him he was clearly only half the man he thought he was;-).  )

However.  With that information from human sperm transposed to cattle here a some hypothesis........

1) young bulls tend to throw more bull calves in my experience......  Is this because as they are learning the ropes they maybe are slow getting to the hot cow?  Or that they keep re breeding her putting new fast swimmers in the mix repeatedly.  Either way would mean the cow is getting bred late in the cycle when the egg is more likely already there.  Meanwhile our older bulls that get the hot cow bred and move to the next tend to throw heifers 60/40...

2) could a rush of heifers go back to the summer and nutrition?  Perhaps mineral imbalance, or nutritional deficiency or heat wave or something to put the cow (or bull) at less then optimal condition screwing the odds to the hardier female sperm

3) could some cow families release the egg later or earlier relative to standing heat?  Dropping the egg early more bulls, dropping the egg late, more heifers.  Could an environmental trigger also cause a delay on Gnrh dropping the egg?


I have always wanted to play with AI timing and breeding late and breeding early and seeing how much that would change heifer bull ratio.....  Problem is we AI only a few and I am not willing to risk missing many for an experiment.....  But I do cheat the 12 hours one way or the other depending on what I am hoping for.....

Nice post, I have wondered the same thing and have always been told 50/50 and obviously the odds don't change, but you wonder if there is something genetically in the male sperm that would play a role in the ability.

 

[justintime]

I have seen sex difference percentages over the years but I have never had a year like this one. We ended up at just over 85% bulls in this years calf crop. They are sired by 4 herd bulls and there are also about 25 ET calves from several sires. Actually  we had more heifers from the ET calves so the calves from our herd bulls were almost 90% male. We ended up the calving season with a run of 22 bulls in a row. Even the calves we have in a cooperator herd 600 miles from here is over 80% males. I have talked with a few neighbors and most of them are saying they have more heifers than bulls this year. I am assuming that my percentages are a purely random but I often wonder if there are other factors as well. 

A few years ago, we had two years in a row where we had 70% heifers, but I have never had a calf crop as far off center as this one. The good news is I have been wanting to start reducing my cow numbers some and it gives me a great set of bulls to select from for our bull sale.

 

[insjockey]

Had a guy tell me once that the heat/drought will effect the bull and that could cause more bull calves.

I have a cow that I would love a heifer from have 4 straight bull calves.

 

[Will]

We have finished our spring calving 31 cows with 24 bull calves and 7 heifers.  The one thing I will say is I am very excited about 3 or 4 of the heifers.