Pulling bulls

This week we are pulling our bulls. If you aren't certain what I mean by that, we are not going to physically pull them around (assuming their are no attitude issues), and what I mean by that statement is we are going to take them out of our cows.
Ranchers can manage when they start calving by when they turn their bulls out with their cows. They manage when they stop calving by when they take the bulls out of their cows. This is all assuming the neighbors bull doesn't pitch it before or after your bulls are with your cows. Artificial Insemination (AI) is another very effective way of managing calving, but we don't currently use that method and this will focus on natural breeding.
Managing your calving season is important for several reasons, one being that you want to work around the weather in your area, especially if you don't have adequate protection in case of bad weather. Another is that the closer in age all your calves are, the more uniform they will be their entire lives.Your firstborn calves will also have the competitive, size and age advantage over their younger counterparts for their entire lives. When you will market the calves is another thing to keep in mind when choosing a time to calve.
We strive to have all our calves born as close together as possible each year so they are uniform, easier to manage (think one branding instead of three because calves keep being born for several months), and more marketable (extra big or small calves may be sorted off when you sell).
But, we also want as many cows to calve as possible, and it's not economical to turn a bull out for 10 days, and only get a 50 percent or so calf crop. A cow's estrus cycle lasts 21 days, and gestation length is 280-some days, or about 9 months. So, for each cycle you leave the bulls in, you extend your calvig season by one month. With that in mind, we will typically leave our bulls in for one, two or three estrus cycles (called simply cycles), depending on the group of cows, year, and other factors.
Lots of people also put bulls with their first calf heifers sooner than they put them with their mature cows. This is because calving sooner will give the heifer more time to put on condition post-calving, and before she is turned back out with a bull to breed again. Trying to get a cow to breed back after she's had her first calf is one of the most challenging aspects of livestock reproduction, and a lot of management decisions are geared toward getting her pregnant for a second time.
To put it in perspective, since June 15, when we turned the bulls out with the cows, we have been managing what will be happening on our ranch starting next March, and on through the remainder of next year with our next calf crop. Or, you can think of it the opposite way, in that we have been managing for this year's calf crop that we're about to wean since June, 2011, and actually before when we purchased the bulls that sired them. As in many cases, this is one area of ranching that takes significant planning and investment long before you see the fruits of your labor.
This year we left the bulls in with our yearling heifers, who are those being bred for the first time, for 40 days, or two cycles. This gave every heifer two chances to get bred. If she didn't breed she will be sold, which eliminates the least fertile females from ever entering our mother cow herd. Often times we only leave the bull in with the heifers for one cycle. This ensures we are retaining the most fertile and efficient females into our herd, and makes calving heifers last one month instead of two. The less time spent calving heifers the better in most cases, plus it goes back to having a uniform calf crop and giving each heifer more time to gain condition before she's expected to breed again.
In our mature cows, the bulls are going to be pulled at roughly 60 days, or three cycles. These cows are in much larger pastures, have a calf sucking on them which uses more energy and can make it more difficult for the cow to breed back, and have already had enough money invested in them to make it worthwhile to give them three chances to get bred.
Another key consideration in putting in and pulling bulls is that gestation length in cattle varies, just as it does in humans. Different bulls and different cows will throw calves that are born early, right on time, or late. So, since we turned the bulls in on June 15, we will expect to start calving at least one week early. This is particularly important in our heifers because we use low birthweight bulls, and the way you get a lower birthweight is through a shorter gestation period. Combine that with that fact that we are continuously available to help our first-calf heifer during calving, and it becomes something to pay close attention to.
Some years the bulls aren't pulled, typically because we get so busy with other tasks. We also have cows spread out over a 200 mile area, so it's not like we just spend an hour and they're all gathered. For us, pulling bulls is a big "want to" each year, but not a "absolutely have to" management practice.
If you don't pull bulls the vast majority (over 90 percent) of mature cows will still be bred in 60 days in our place. Very few head will be bred later than that. Big deal you may be thinking, and really it's not a catrastrophe, but it is a pain in the neck. You will have to set up a second day to brand those few head, if they aren't branded they will have to sorted off when you're shipping to summer pasture (and they are always in the way during this), and throughout the entire spring you will spend extra time shuffling, sorting gathering those few head. Plus, those calves you have to spend all that extra time on will be worth less than their larger, more mature siblings for the majority of their lives.