By Eric Mousel Extension Cow Calf Educator University of Minnesota Beef Team
Now that most of the calves are weaned or will be weaned shortly, it may be a good time to start thinking about getting replacement heifers started right.
Everybody probably has their own opinion about the right way to get heifers going. Of course, good judgment comes from experience, and a lot of that comes from bad judgment.
Albeit, what works for one outfit may not work entirely for another. Add to that some pretty good research conducted fairly recently that has added some new angles to the process of selecting and raising the future of the ranch. So on the whole, it’s probably worth your time to keep reading to see if anything fits into what you are doing.
There have been volumes written on selecting replacement heifers. Everything from type, functionality, disposition, performance, etc., have been cussed and discussed (depending on what company you keep) as the key criteria for heifers.
All of these, no doubt, are good selection criteria; however, how much can you really tell about a weanling calf that is going to need to carry the ranch for at least the next 10 years?
It seems as though the general philosophy amongst most cow outfits is that like begats like – “If her mama was a good cow, she will be a good cow.” That may or may not be true.
My dad always told me never to judge a man by his relatives and, in general, I think that is a good way to think about replacement heifers. It’s not that like cannot begat like, it’s more that at selection time, we can’t really tell.
Some traits like growth, maternal and carcass traits are very heritable and like will likely begat like. Other key traits such as fertility, longevity, and pregnancy rate tend to not be very heritable amongst a population and therefore like will not necessarily begat like.
So how can you tell the difference in a group of heifer calves?
The short answer is you can’t. But, researchers at South Dakota State University and the U.S. Meat Animal Research Center (MARC) in Clay Center, Neb., may have come up with a solution.
They conducted a study that found that many of the lowly heritable traits such as fertility, longevity, and lifetime production are highly correlated with the individual’s ability to breed early (and thus calve early) as a heifer.
Therefore, heifers that breed first have the highest probability of halving a good calf every year, stay in the herd a lot longer, and produce more pounds of weaned calf than her counterparts that did not breed early as a heifer.
Consequently, the plausible solution is to keep all viable heifer calves, develop them properly, expose them, and keep the ones that breed the earliest. This of course won’t work for everybody, but if you can swing it, it can be a real game-changer for finding the best replacements.
There has been a tremendous amount of really good research on developing replacement heifers for optimum probability of breeding. Traditionally, the target weight for the development process has been 65 percent of mature weight; which tends to be the general signal for the onset of puberty in the developing female.
Recent research conducted by the University of Nebraska has shown that the onset of puberty is usually stimulated by the time the developing female reaches 55 percent of mature weight. This is a really useful benchmark for heifer development programs. That represents about 150 pounds less that a heifer needs to gain prior to breeding and can still settle successfully.
In Minnesota, this generally isn’t a problem. Our problem tends to be making sure heifers don’t get too fat before breeding; $6 corn was probably the best thing to ever happen to Minnesota heifers.
Additionally, rate of gain can play a really important role in proper development of replacement females. Classic research set the standard for rate of gain in replacement heifers by demonstrating that when three different groups of heifers were wintered at three different rates of gain (less than 1 lb/day; 1.5 lbs./day; and 2 lbs/day) the heifers grown at 1.5 lbs./day had the highest pregnancy rates.
Presumably, the low rate of gain resulted in heifers that were too thin and the high rate of gain resulted in heifers that were too fat. Although this research was conducted 50+ years ago, it is still generally the standard for developing heifers.
However, researchers at the University of Nebraska recently conducted a study that indicated supplementation as a positive energy and protein balance in the last trimester of pregnancy resulted in higher pregnancy rates than heifers not supplemented, regardless of rate of gain in the 1st and 2nd trimesters.
Apparently, timing of proper nutrition is as important as anything. Of course, timing has a lot to do with the outcome of a rain dance as well.
The most oft asked question is what to feed replacement heifers. I don’t think it makes a whole lot of difference what you feed them in terms of feedstuffs. As previously mentioned, it has more to do with target rates of gain, proper energy and protein balance at the right time, and cost to do these things.
General energy requirements for growing heifers are going to be in the 63 percent TDN range and a dietary protein level of around 10.5 percent; that will yield about 1.5 lbs. of gain per day.
The combination of feedstuffs that gets them there is really not that important, except for cost. I’ve seen heifers fed everything from slough grass and distillers to potato chips, beet pulp, and canola meal and as long as their energy and protein requirements are met, they do fine.
Probably the biggest thing the average producer can do to improve heifer development is to test the nutrient composition of whatever they are feeding so you know if the diet contains the energy and protein the animal needs.
I think this a good place to stop and, like my uncle Jim used to say, “Never miss a good chance to shut up.” But if you want to talk more about replacement heifers, give me call at 605-690-4974 or email firstname.lastname@example.org.