Selecting and Developing Replacement Heifers.

 By Heather Smith Thomas.

 Many ranchers keep and develop their own replacements, and some prefer to buy bred heifers that are already well developed and pregnant.  Selecting good replacement females is important for long-term sustainability and productivity of your cow herd, whether you purchase or raise them.  Many people like to raise their own, however, because they are often better suited/adapted to their environment, climate and the management system on the ranch where they grow up.

Most stockmen try to keep an adequate number of heifers as replacements to allow for a few to fall out of the program for one reason or another.  They usually select heifers from their best cows, sired by bulls that pass good maternal traits to daughters.

There are many criteria regarding which heifers to keep and which ones to sell, and most producers have certain goals.  Commercial cattlemen want heifers that will be fertile, productive, long-lived cows that stay in the herd a long time producing good calves.  The cost of raising/developing a heifer is high because she won’t have a calf for you to sell until she’s a two-year-old.  So it’s better to select females that can produce well into their teens than have to sell some of them for various reasons after a few years and replace them with expensive heifers.  

Purebred breeders want heifers that will produce high-quality seedstock—bulls or females—for their customers.  Some breeders look first at performance records and then visually evaluate the heifers, while others make their first sort in the corral/pasture and use records as a final tie-breaker.

The wrong kind of females won’t generate as much profit and may cost more than you can afford in additional inputs.  How you manage heifers from weaning to breeding is very important, and when done correctly can be part of the selection process, to make sure you end up with heifers that can do the best job.

Regardless of a heifer’s performance records, pedigree, EPDs of sire and dam, etc. (if she’s a purebred) she must also have other qualities that are more difficult to measure.  You can’t select heifers on records alone.

Weaned heifer calves won’t generate income for two years.  Rather than put them in a high-input, artificial environment, hauling expensive feed to them, some ranchers feel they should be treated like the cows they will become.  On most ranching operations they need to be out foraging, with minimum inputs from you.  If a heifer can’t do this, she probably won’t make an efficient and profitable cow.  Seed-stock producers who raise bulls or heifers in an artificial environment do their customers a disservice if the animals can’t perform optimally in the real world.

One solution is to retain nearly all heifer calves, roughing them through winter and exposing them to a bull for a short time (one or two heat cycles).  This allows only the most efficient and early-maturing heifers to become cows.  Your ranch environment will sort out your best replacements.  If you preg-check early, the ones that didn’t breed can be sold at the peak of the yearling market.
If you breed heifers to calve in April or May, most will conceive during the first part of the breeding season.  Even heifers that were a little thin during winter can catch up--with two to three months of green grass before breeding.  If you end up with more bred heifers than you need, you can sell the extras as bred heifers.

Selection
Your environment will do the best job selecting heifers for function, efficiency and fertility, but there are a few other things to consider as well.  If you make selections at weaning (rather than keeping more heifers than you need and letting nature sort them), first cull off any outliers (too big, too small, too tall).  Heifers with “average” size and build usually end up being your best and most fertile cows.  Many producers make the mistake of keeping the biggest heifers, and end up with cows that are too large.

Choose the older heifers, not the biggest.  Those born early in the calving period had fertile mothers.  Choosing heifers born from the first or second cycle puts more emphasis on fertility and on keeping a short calving interval.  There are several reasons the younger heifers in the group might be less successful.  They may have dams that are lees fertile (calving later) and have less time to mature enough to have a cycle or two before you start breeding them.

Evaluate disposition.  Cull any heifers that are flighty or nervous.  Some of those wild ones will be obvious but others might not be until you separate them from their herdmates.  One way to check is to sort them quietly in an alley.  Bring each heifer to the other end alone, to see how they respond to being handled by themselves.  If you push them, almost any heifer will try to get away, but when you back off it’s easy to see if they settle back down or stay wild and scared.

Evaluate feet and leg structure and general conformation.  Any problems you can see in a weanling will probably get worse.  Select heifers that look feminine rather than blocky, coarse and masculine. You don’t want a heifer that looks like a steer; her endocrine balance may be off and there’s more chance she’ll come up open.  You also don’t want a heifer that’s extremely long-necked or two short-necked (which makes her look like a male).  Many people pick their biggest, most muscular heifers but this leads to bigger-framed cattle that are not as fertile.

You want easy-fleshing cattle but this is harder to evaluate at weaning because a fat heifer may have a dam that milked too well.  The dam may be thin—having put all her “groceries” into milk and sacrificing her own body condition.  

It’s easier to evaluate a heifer’s own fleshing ability after her first winter, before her first breeding season.  A heifer going into the breeding season without enough fat won’t breed.  She probably won’t last in a difficult environment.  If she doesn’t flesh as a yearling she won’t flesh as a cow.  She’ll fall apart when she’s lactating, raising a calf. 

Evaluate the dam.  Are her feet and udder sound?  Udder structure is hard to judge on weanlings or yearlings, but you’ll find outliers that are obviously undesirable, such as heifers with teats that will be too long or fat.  You may not be able to determine subtle differences, so look at her dam.  The sire can also make a difference, if his daughters have good udders (inheriting traits from his mother).  Many people want to see the sire’s dam and evaluate her udder, because a bull whose mother had a bad udder will often pass this undesirable trait to his daughters.

Does the heifer’s dam have good temperament?  Do you have production records and weights on her calves?  Has she had a calf every year? There are many things you can’t tell about the heifer’s potential, without evaluating her mother.  Choose daughters from cows that have produced for several years and haven’t missed a calf—calving early every year.  You don’t know what a heifer out of a first calver will be like, but you have a pretty good idea about calves from a 10-year-old cow that’s always been fertile and has produced good calves.

If you are making your decisions after the heifers have gone through winter, select the heifers that shed quickest. This is an indicator of health and vitality.  A highly productive, feminine, fertile heifer will be one of the first to shed in the spring, and has a soft, smooth hair coat, compared to a male.

Some producers palpate and measure pelvic width in heifers, since some females don’t have a very wide birth canal.  Selecting heifers with adequate pelvic size prevents calving issues and you might also detect something abnormal like a bone spur.  You can often tell if heifers have adequate width through the pins just by looking at them, but measuring them after they reach puberty can be helpful.

There should be adequate slope from hooks to pins. This is one of the most important factors for ease of calving, but is often overlooked by cattle breeders.  All wild ungulates (elk, deer, moose, bison, etc.) have a sloping rear end.  Cattle that are level from hooks to pins have a serious man-made fault.  Some people like square hip but this is a detrimental trait.  Many producers also tend to choose cattle that are straight in the hind leg, but this is unnatural conformation.  All wild animals are cow-hocked, and have some angle to the hock joint when viewed from the side, which is stronger structure than straight hind legs or post-legged.  We need to copy Mother Nature.

A straight hind leg changes the angle of the leg, rotating the pin.  When the hooks and pins are level, the hind legs are too straight (construction that often won’t hold up) and changes the angle of the pelvis.  This makes it more difficult for the calf to come up through the pelvis in a natural arc during birth.  The calf’s feet tend to jam up against the backbone and tail head.  Lack of slope and smaller birth canal also makes drainage from the reproductive tract more difficult. The short tail head also moves the anus forward, with vulva tipped forward.  Like a “windsucking” mare, fecal material falls into the vagina.  Many of these sharp-tailed, level-pinned cows come up open or are harder to calve.  If there is adequate slope, the birth canal is more open and has more room.

Development
Traditional recommendation has been to have heifers reach 65% of their eventual mature body weight by time of breeding. This is why many producers confine heifers after weaning and push them to gain more than they would on winter pastures.  Other ranchers raise heifers on pasture (feeding hay and supplement if needed) feeling that unconfined heifers stay fitter, healthier and make better cows, even though they don’t grow as fast as intensively-fed heifers.  The genetics of many herds have changed; some producers have selected for more efficient animals that do well without grain, needing less expensive inputs for growth and production.  With the right genetics, easy-keeping cattle can grow and develop on forage alone and never need grain.

There has been research on this; there was concern that puberty would be delayed if heifers were raised with lower rate of gain and lower percent of mature body weight at breeding.  Some of the earlier work was all about insuring that they would reach puberty and breed on time, but there’s also been some work to see if there’s an alternative.  Studies have looked at developing heifers to 60% or maybe just 55% of mature weight.

Success depends on genetics.  British breeds are a better fit for this lower percent than some of the continental breeds.  Ranchers can develop cattle that fit their ranch environment and thrive on the grazing resources the ranch provides, without expensive inputs during the 200 days from weaning until breeding.  

One Canadian study looked at two rates of gain for developing heifers—moderate versus high, and an extensive grazing program versus a drylot feeding program.  This study separated the heifers into four groups that had different feed inputs: moderate gain in extensive grazing, high gain in extensive grazing, moderate gain in drylot and high gain drylot.  The goal was to expose some replacement heifers to a system they would be managed in for longevity—an extensive system where they have to go find feed versus having it brought to them in a bunk or pen.  They had to graze, winter well, and then cycle during breeding season and give the producer a calf.  Most ranchers want heifers that can utilize crop residues, stockpiled winter range or pasture, standing corn, or whatever the ranch can grow cheaply for winter feed.  

The study looked at moderate versus high rate of gain and followed the heifers to their third calf.  Most research programs just follow heifers to their first pregnancy diagnosis but not beyond.  Theis study followed them farther, to see their retention rates within the herd.  Whatever system we use for developing heifers should be for longevity and not just making sure they can breed as yearlings.

During the development program after weaning, the moderate-gain group gained about 1.2 pounds per day. The high-gain group averaged a little over 1.5 pounds per day.  At weaning, they were all about 565 pounds.  The heifers with moderate gains weighed about 780 just before breeding, and the high gain group weighed about 870.  A few lighter-weight heifers had not reached puberty coming out of winter but they did reach puberty during breeding season, started cycling, and did become pregnant.  If pasture quality is adequate, they do catch up.