Age of Bulls?

[aplusmnt]

Wondering if I could get some general information on Age and or Size of bulls that would work on heifers and Older cows. What is the youngest a bull can usually cover full grown cows and what age is he usually to big for heifers? I know there is lots of variables as far as types and size of cows. What kind of typical window would there be on moderate framed cross cows with moderate to larger framed Bull.

 

[cypressfarms]

Hey aplus,

I'll give this one a whirl, but there are plenty of other people with more experience than me on the board, so take it with a grain of salt:

1. The age that a bull can breed will depend on his breed. Heard of British breeds firing bullets as young as 7 months old. However, a bull this young normally should not be used. Some farmers where I live will put yearling bulls (12 to 16 months) on cattle, but they only put one bull per 8 to 10 cows. That is if the bull is large enough. If you have a particularly small angus, for example, trying to breed a huge full grown simmental, he may have trouble reaching her. I normally use a yearling for a few cows just to get him in the working frame of mind, and to see what type of calves he will throw. I would normally wait until the bull is two until I would expect him to be able to earn his keep, but even then he won't be able to cover as many cows. An ol' timer said that a bull can cover as many cows that he is months old. Not sure that I agree, but there it is.

With Brahman, or brahman crosses, you may have to wait slightly longer as they mature slower. At 12 months my brangus bull had a relatively low sperm count, but by 18 months he was fine. Which brings up another point. Spend the $30 to $50 it costs to have your bull semen tested and get a "breeding physical" before you put him with cows. May save you the loss of a calf crop.

2. Your second question dealt with heifers, and if they could handle the size of the bull to breed. Many people breed a heifer at 15 months to allow her to calf by 24 months. A 15 month old heifer should not have a problem supporting a bull, but again moderation is the key. I wouldn't want a 2,500 lb. charolais on my heifers at all. I good low birth weight bull with a moderate size should pose no problems. BUT your heifers must be 60 to 70% of their projected mature size. Heifers will come into heat, normally, before they should be exposed to bulls. (That is to say that heifers can start cycling at a young age, but may not be at that target weught yet)

Hopefully this helps

 

[Scotty]

Just because he is young does not always mean he is safe for heifers. On tip i would give is if you are going to use a yearling on heifers is put them in a small trap. They will run his young butt all over a large pasture. Been my experience that heifers will let them ride longer. Be sure to keep an eye on his physical condition. Don't leave him in to long.




Scotty

 

[Jeanne - Simme Valley]

I think Cypressfarm explained it very well.
Some bulls tend to be "hard" on cows & heifers, and others are super gentle mounting even the smallest heifer.
A "well grown out" yearling should be able to be put with 8-14 females (that he can reach) by 14 months old. And yes, I've heard of the 1 cow per month "guide" and believe they still say that's pretty accurate. Now, like CPF noted, some BREEDS are more fertile at a younger age than others. Even though Simmental are Continentals, they "mature" younger than even many british, whereas the Charolais & Limos are slower developing sexually.
Just use common sense in matching size, which I think you already indicated that by mentioning moderate size cows with a moderate to larger frame bull.

 

[MikeC]

Jeanne wrote:

whereas the Charolais & Limos are slower developing sexually.

I will have to disagree with you here. If given adequate nutrition most any bull has the ability to breed cows at 12 months. In fact, I have had some Char bulls with the ability to have a full erection at weaning , plus have the scrotal maturity to produce 600 straws of freezeable semen per day in two jumps at the stud at one year of age.

I cannot speak for the Limos, but I urge you to compliment your own breed without degrading others.

Different herds of all cattle have different length of maturity traits Jeanne, it's another part of genetics that we have the ability to use in our breeding decisions.

 

[mgman]

I have used a 12 month old Murray Grey bull on 15 cows/heifers and he covered them fine-they all calved in a 70 day window.
My current MG herd sire was turned with 25 cows/heifers at 16 months of age and every one of them is bred.
I was a little concerned about both bulls ability to reach some of my bigger framed cows, but in both cases they got the job done with no problem.
Another thing to take into consideration is the conditions the bull will be breeding under-a yearling bull will probably do fine for you with plenty of good pasture, but may not do nearly as well under range/drought conditions. If you're planning to use a yearling bull you definitely want to make sure his nutritional needs are met so he doesn't lose excessive weight or end up not reaching his full growth potential.

 

[dun]

Granted this is the 1977 study, and some things have changed. It's from the MARC study on composite breeds. I would think that female and male puberty would run fairly parallel.

 

[Jeanne - Simme Valley]

Jeanne wrote:

whereas the Charolais & Limos are slower developing sexually.

I will have to disagree with you here. If given adequate nutrition most any bull has the ability to breed cows at 12 months. In fact, I have had some Char bulls with the ability to have a full erection at weaning , plus have the scrotal maturity to produce 600 straws of freezeable semen per day in two jumps at the stud at one year of age.

I cannot speak for the Limos, but I urge you to compliment your own breed without degrading others.

Different herds of all cattle have different length of maturity traits Jeanne, it's another part of genetics that we have the ability to use in our breeding decisions.

No, No. I was not trying to "slam" any breed. Just pointing out that there are differences in breeds' sexual development.
Most people put all british breeds & all continental breeds in a lump picture & that is wrong.
In any case, there are more differences "within" a breed, than there is "across" breeds. I was just stating breed average research that has been reported that way for many years.
Sexual maturity might be something you have been working on and you can be proud to have improved that trait. My hats off to you!
I have been on the NY bull test committee for 25 years, and I know that Charolais & Limousines have a tough time qualifying for the minimum 32cm scrotal circumference at 12 months of age - across the breed. Some individuals outsurpass all the bulls of all breeds. But, usually it would be bulls from the same farm - genetics.
I know in years past, the National Limousin assn. acknowledged their breed problem & recommended bulls with less than a 34cm sc to be used for terminal cross only, because they were having so many females in the breed being culled for fertility as heifers. Maybe by now, their breed average age for cycling is lower. But, I have not seen any research showing any major differences over the past few years.
That's why we have to analyze each bull/female as an idividual. They may be non-typical for the breed averages as reported by research.
I try not to "slam" a breed. But, I am not afraid to repeat research info. Facts are facts, averages are averages. There is good & bad in all breeds. There are a lot of Simmental breeders that hurt our reputation. But that's life.

 

[Jeanne - Simme Valley]

Dun, thank you. I looked but couldn't put my "keys" on that info. There has been more recent research, and it's been about the same each time I've looked at it.