bulls and breeding cows

[poorboy]

I am looking for some advice on how to introduce bulls to the breeding cows and number of bulls required. I notice that when breeding in a confined area with a large number of bulls that each cow seems to get bred numerous times by each bull. So, the first obvious question, is how does bull semen develop? Can each bull make enough semen to breed each cow and have enough to breed all the rest of the cows also? Or do they taper off and all run out of semen after a certain point? If for example I have a 100 cows and 5 bulls in a 6 acre pen and want to breed them and put all 5 bulls in at once, then each cow in heat will get bred by each bull. This would mean that each bull will breed 100 cows. I observe the multiple breeding of each cow, so I know that is true, but I don't know if a lot of the bulls are running out of semen after about 2 weeks of breeding.
Should each bull be turned in for a week and then removed to rest, while the next bull gets his weeks turn?

My next question is based on the number of cows to have for each bull. Most of the numbers seem to be based on large pasture breeding, where the cows are scattered all over 3 or 400 acres and it requires lots of bulls, so that each small group of cows has a bull. In this sitution 20-30 cows per bull would be a nice number because the cows can be spread out. However, in the pen breeding, if every bull breeds every cow, we have 100 or more cows for each bull.

Just looking for what is the correct answer, as it appears to be a grey area to most producers. I typically start breeding about 21 days before my grass is really growing well and my herd is tightly grouped for daily breeding, so the bulls have no trouble finding the cows that are in heat.

[grassfarmer]

Poorboy, as long as your bulls weren't firing blanks to start with they won't ever "run out" of semen. Get them semen checked at least once when they are young and if they are good use them with confidence.
I have read an awful lot about how many cows you should allocate per bull since moving to Canada and it does conflict a bit with the practises in the UK.
As you say cows running at 40 acres per cow need a bull that will travel a lot of miles and I have no experience of that scenario.
In Scotland we used to run 40 cows with a mature bull with no problems (in a tight 6 week breeding period)These bulls often went on to breed another 30-40 cows in the fall breeding season.
Bulls certainly are a lot cheaper in Canada, relatively speaking, so producers are encouraged to use more bulls(often by bull sellers!)
It depends on breed too - Charolais I find are sometimes guilty of being lazy whereas a Luing bull will cover more females than any breed I know (mature bull will cover 60 cows)
To me it depends how much weight the bull carries and where it is distributed. A tonne exotic bull carrying a lot of meat on his backend is physically going to struggle more than a scrawny 1700lb longhorn that is all legs and horns.
If you need to breed 100 cows in a 6 acre pen I would use three bulls - at least if two are fighting one is left to work. You don't need more than that but if you have them you may want to change them over after 3 weeks.

Another suggestion might be to calve with nature - you say you get them all bred in pens before the grass is actively growing. To me that indicates that all your cows big feed requirement periods (immediately pre-calving, post calving,milking and rebreeding)are being met by winter feeding of conserved feeds. It's a lot cheaper to calve when grass growth is at it's peak and winter feed them when they are at their lowest feed requirement period
of the year.
My bulls go to the cows when we are grazing 60-70 cows/acre/day in late July - that saves the bulls a lot of walking too!

[whiteface]

I breed in corrals too starting next month. Any herd bull I've ever had 2 or over could handle 40 cows without batting an eye. Three, four in heat in a day, every bull I raised could take it. I have never had an instance where a good semen producer "ran out" of semen or desire to breed for that matter, a complaint I do hear of quite often. A good bull will pace himself, breed a cow once or twice, on to the next one, then again maybe I've been just lucky, with some good herefords (and doesn't sound to me like there are an awful lot of good bulls of any particular breed...I hear all kinds of complaints all the time.)
I don't run multiple bulls on huge pastures for all kinds of reasons but I know a few who do and it seems to be between 20-60 (yes I know that's a huge spread and doesn't help one bit) cows to a bull and for the life of me I really wonder about some management practices but I'm sure everyone has their reasons.
I agree with grassfarmer about if you're going to run multiple bulls make them odd numbers (two fight, the other tries to breed and breaks a penis in the process when one of the other two blind side him) but I sure don't recommend multiple bulls (how the hell can you know whos siring your calves that way!!!?? Just seems ridiculous to me...but what do I know?
Get a good bull or two and I kid you not, hang on to him for dear life because it does seem to me that some breeders of bulls just aren't working all that hard anymore based on the complaints of bull buyers. Some guys will sell you a bull just because it's say black, or it's mother was a champion or his e.p.d.'s are "off the chart" or whatever. A good bull will perform and you won't need six to a paddock getting hurt or worrying about running out of libido or semen. If you feel a need to run all your bulls in that small an area, if it's not too much work, I would rotate once a week. That's just what I would do for various reasons, I'm not suggesting I do things better, just I know what is working for me and I don't think I'm a rocket scientist by any means, I'm sure some of my methods could work for others. Good luck and hey, I need pipleine advice, what can you offer me?
Have a good evening all!