In nearly five years of writing these columns, I have received more questions, comments and thank you emails regarding my recommendation to reduce bull exposure for yearling heifers to 24-30 days than for any other idea. I started out recommending 30 days because that is what I had done for a number of years. Now, after watching a number of others shorten the breeding season for heifers, I much prefer 24 days when using bulls or even shorter if using AI and synchronization.
Let’s examine some of the effects of this shortened breeding season:
- The shortened calving season gives the heifers a significantly longer post-partum interval to prepare them for the next bull exposure.
- Heifers that calve as a result of first-cycle conception have a distinct lifetime production advantage over those that calve as a result of second- or third-cycle conception. On average, the heifers that calve later can never catch up to those that calve from first-cycle conception.
- In subsequent years, pregnancy rates for two- and three-year-olds will improve. The heritability of fertility traits is said to be low. However, I think that is a problematic statistical measurement and would argue that, at least some components of fertility are more highly heritable. I think that first-cycle conception in yearling heifers is one of those traits. Perhaps the interval between first and second calving also could be more highly heritable, especially within one’s own environment.
- Following cost control and stocking rate, which is achieved through grazing management and downsizing cows, realized cow herd fertility is the next most important component of ranch profitability. Whether achieved by management or genetics, it is highly important. However, profitable management cannot include a lot of fed feed for heifer development. Perhaps the genetic component becomes more important and effective when the crutches are removed and the animal has to conceive as a result of natural inborn or inbred fertility.
- As some ranchers have reduced hay feeding and/or other supplemental feed inputs, they have experienced difficulties in getting two-year-old heifers to rebreed after calving. Sometimes they even have trouble getting an acceptable conception rate on yearling heifers. Their solution is to not breed heifers until they are two years old. I think that is a poor solution. You cannot afford to lose that year of production. If two-year-olds won’t rebreed at acceptable rates after calving and especially if yearlings won’t settle at acceptable rates, it is highly probable that your cows don’t fit your environment and management. Perhaps you need to remove the crutches a little each year while you are developing a herd of low-input, efficient, practical cows.
- Nature and the bulls can select replacement heifers with much more accuracy than we can. If you remove only the obvious misfits, develop heifers to reach approximately 55% of their expected mature cow weight before breeding and expose them for one cycle, you should have more pregnant than you need. If you don’t, I will again suggest that your cattle do not fit your management and environment; but you will have started a selection method that will move your herd in the right direction. If more heifers conceive than you need, you can sell a few bred heifers or bred cows. I prefer to sell bred cows.
- The open yearlings should be a good profit center. Except for turning bulls in, they should have been run like stocker cattle. Then selling a late-bred cow which is replaced by an early-bred heifer should be a bonus.
- If you want to have high realized cow herd fertility, you will sell late-calving cows and, little by little, move the cutoff time closer and closer to 30 days of calving. I only count the days after “due date” even though a good number of calves are usually born before “due date.” When you sell every cow that calves after the first 30 days, you will soon sell very few open cows and quite a few pregnant cows which usually sell for a nice premium—especially when people know how well they will work in a terminal breeding program. This is what I call a “long breeding season and a short calving season." ”To accomplish this, you’ve got to be disciplined and ready to market; but aren’t discipline and good marketing essential parts of good management and profitability?
- If you do this, you will have begun to select heifers and cows to fit your environment and management. Remember, a cow can’t differentiate between the natural environment and what you add to it. Add as little as possible. For most of you, the heifers that conceive will probably be a little smaller than average; and, as a result, cow size will slowly decrease unless you continue to use large bulls and ignore what nature is telling you. You will have higher conception rates for all ages of cows except yearling heifers; and that will improve with time. Wouldn’t you rather cull them as yearlings than later in life? They have good value as yearling feeder heifers. It will take a few years; but you will end up with a herd of efficient cows that fit your environment and can get by with little additional input to what nature and your grazing management provide.
- It allows you to have the same breeding and calving season for heifers and cows especially if you are breeding and calving “in sync” with nature. This makes grazing management, limited feeding and supplementing much easier.
- Now you readers with 100 cows or less, shouldn’t you consider developing a relationship with someone who produces cows like those described? You might need to replace 12% to 20% of your herd each year. You could buy those cows, not heifers, and breed them all to a terminal cross sire emphasizing growth and carcass.Your cows could all be in one herd and managed alike. Since the purchased cows are bred for fertility and low input, you should expect good conception rates and every cow has the possibility of producing income each year with little culling of cows. If you choose the right bull, buyers should love your calves and your life will be simpler.
- I have observed that a number of ranchers with smaller herds like to expose yearlings and two-year-olds together to reduce the number of herds and the number of paddocks needed for well-planned grazing. In these cases, they may breed heifers for a longer period of time or move the two-year-olds to the mature cow herd to finish the breeding season.
- If they breed for a longer period of time, they may sell the heifers that settled after the first cycle (using ultrasound for pregnancy testing) as pregnant heifers. Or, more than likely, they will calve them once and sell them as bred three-year-olds. This option is taken because those who buy pregnant yearling heifers seem to want the overdeveloped, heavy heifers, thus leaving the properly developed, lighter heifers to sell at a discount.
- If you begin to sell some pregnant three- and four-year-old cows that conceived in the second or third cycle, remember they are not infertile. They are just not as fertile as the ones you kept. They were still trying to grow while nursing a calf as two- and three-year-olds. They could be a little too big for your environment; but, when they quit growing, they could be very good cows and even breed back a little earlier. They can make excellent cows for terminal crossing because none of the daughters are retained as replacements.
You might also like: