% bulls to heifers

[Frankie]

We almost always have more bulls than heifers born here, usually at least 2-1. Do you think it's because we AI everything? I don't mind that ratio because we have a better market for bulls, but it has made building our cow herd numbers back up difficult. Anyone else with an AI program see this ratio?

 

[redfornow]

The reps say its 50-50 but I dont buy it...
I get 50-50 or at worst more females out of my bulls.
but with AI I have always got about the same numbers you have been getting?

Maybe its just bad luck? Cause around here AI bred heifers are easy to market and sale if they are good ones?

 

[milkmaid]

Neighboring dairy that did all AI (sold out recently) told me once that they ran 30% heifers, 70% bulls.

 

[Frankie]

In 2000 we had more heifers born than bulls. Other than that once, I don't think it's ever happened here. I don't mind the heifers, but we don't usually sell open heifers. We'll get them safe in calf or even wait for them to calve and sell them as a pair. So we've got more time tied up in them than the bulls.

 

[novaman]

This is the first crop of AI calves for me and I'm about 65% heifers. Of course that's a wonderful thing on a dairy as the bulls are worth diddly to me. I'm just hoping this isn't a fluke. My luck next year will be the complete opposite.

 

[Tod Dague]

Typically about 50-50.

 

[dun]

In previous years we've ended up right at 50:50. This year it was 70% bulls, the bull had very slightly better average then I did with AI. That must mean that next year we'll be overloaded with heifers.

 

[Willow Springs]

We tend to be about 60% bulls and 40% heifers. I don't think that I've had a year since 1996 where the heifers outnumbered the bulls. We also do a lot of AI. It is nice to have bulls to sell and the steers are worth more than heifers, but like you said it has been hard to build the herd around home raised females.

 

[KMacGinley]

My theory is that it depends on the timing of the AI.

My repro professor at Purdue said that XY(male) sperm cells swim faster than XX(female) cells. XX cells have more stamina and survive longer in the female tract.

To get heifers, I AI immediately when I see the cow in heat. I do not wait the 12 hours. For every 10 we do we get about 7 out of 10 heifers pretty consistently.

The 12 hour wait puts the speed demon XY cells on the spot when the egg reaches the fallopian tube. By the time the XX cells show up, the ballgame is over.

I think it also works in human reproduction, If going for a boy, the more often you try, the more likely you are to get a boy, at least that is what I told my wife. I always feel sorry for those guys that have all daughters.

 

[KNERSIE]

To get heifers, I AI immediately when I see the cow in heat. I do not wait the 12 hours. For every 10 we do we get about 7 out of 10 heifers pretty consistently.

How much does this lower your conception rate on the first AI service?

 

[KMacGinley]

Not not in any meaningful way that I can tell, still around 60-70 % first service. I did arm service for ABS for a couple of years and have been in thousands of cows so that probably helps me.

 

[plumber_greg]

I had some old timers tell me years ago that if it was gonna' be a dry year, you would have more heifers born than bulls that year. Anyone else heard this? gs

 

[dun]

If it was "strictly" a timing thing you would expect natural service to give 100% heifers.

 

[dun]

I had some old timers tell me years ago that if it was gonna' be a dry year, you would have more heifers born than bulls that year. Anyone else heard this? gs

During the 3 years of drought we still averaged out 50:50

 

[grannysoo]

We don't AI, we let the bull take care of business for us. Using the same bull for the last two years, in 2008 we had 70+ % bull calves, in 2009 we had 60+% heifer calves. Go figure...

 

[KNERSIE]

I agree that over a period of time you'll average close to 50:50 bulls and heifers, especially so with natural service, but in my experience selective AI and more so selective AI on induced heats tend to skew the ratio in favour of bulls. I run usually 60+% bulls with AI so replacement heifers from AI are usually not as plentiful as I'd like so I try and use a highly maternal bull as a clean up sire on the registered herd. My thinking is that I am unlikely to keep many bulls out of the clean up sire, but am very likely to sell heifers or even retain a few out a good maternal bull of my own breeding.

 

[Alan]

I'm still waiting for it to get 50/50. as of this point over the 7 or so years I've been doing my hobby thing I'm at about 65% bulls. With AI I have 7 bulls and 1 heifer. I have also heard of the faster swimmers and longer livers.... with breeding horses. Maybe I start working close to 50\50 ratio this year, I'm setting CIDR's in the first group today.

Alan

 

[Jeanne - Simme Valley]

I also believe in early AI for increased heifer ratio. I can't give a %, but you definately have lower conception breeding early. You are taking the risk of ALL the sperm dying before the egg is released.
We breed early the first 3-4 weeks, then breed normal - going for conception. We ALWAYs get the majority of heifers the first month of calving.
Last year, we had lots of replacement heifers, so I purposely did not breed anything early. We ended up with 2:1 bulls to heifers. Which was just what I wanted.

 

[Frankie]

For what it's worth:

RECENT RESEARCH RELATED TO GENDER PRESELECTION

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.

A recent article published in Animal Reproduction Science presented some interesting data to support the timing theory. Using a device which detects changes in vaginal/cervical mucous around the time of estrus, these researchers varied the time of insemination and supposedly skewed the sex ratio of resulting offspring with 90% accuracy. However, the data set presented was extremely small (13 to 14 animals/treatment). Until these results are duplicated in other laboratories and/or on a much larger scale, I'd consider this technology for altering sex ratio as strictly experimental.

An abstract presented at the 1998 Animal and Dairy Science meeting from Dr. Ray Nebel's lab at Virginia Tech, compared the gender ratios for 822 calvings as affected by time from first mount to insemination. First mount was identified by the computerized "Heat Watch" system and time to A.I. and gender ratios were retrospectively analyzed. Dr. Nebel's data (figure 1) would not support the theory that timing of A.I. has any affect on gender ratios.

http://www.selectsires.com/growingpains5.aspx

 

[KaitlinLego]

I dont know if this has anything to do with it, but at my schools show barn, we AI'd 5 heifers. Our results were 4 hefiers and one bull calf. All of the show heifers have much more weight on them than the heifer that had the bull calf. I know that the fatter a cow is, the harder it is to breed them, but, is it possible that becuase the cow is fatter it takes longer for the XY to get to the egg, and so they dont make it there? but the XX make it their alive becuase they are stronger?