Selection and development of replacement heifers (Proceedings)

When discussing replacement heifers in a beef herd, a few questions must be answered before we even select our first potential replacement. First, does this farm or ranch need to calve out heifers? Reasons for never calving out heifers could include labor shortage at calving time; lack of facilities in case of dystocia; historically poor nutrition of young cows and heifers; and historically poor fertility of nursing two year-olds. If any of these situations are present, buying bred cows or cow-calf pairs is likely the most pragmatic option available. There is nothing wrong with this option.

If calving heifers seems to be a positive option, then we must decide if the owner will retain his own heifers or purchase his replacements (bred or open). Reasons to keep your own heifers include less disease risk; less costly (?); herd has excellent genetics; herd has excellent records; and known disposition of heifers. Reasons to purchase heifers would be nearly the opposite of the previous list along with: desire to keep current herd bull that is the sire of your heifers; want to introduce new genetics into your herd; desire to use a terminal cross bull and cheaper to buy than raise your own.

The reason that I mention options other than the traditional "breed what you produce" is that many producers would benefit from purchasing females for the various reasons listed above. Look at the swine industry where 15-20 years ago the majority of producers raised their own replacements and now the majority, purchase their replacements. The beef industry will likely never change to the extent that the swine industry has due to the extremes in environment that we all face. But, I am quite certain that the fed cattle market will continue to become much less tolerant of cattle that don't fit the most common grid marketing options.

Another question we must answer is "is keeping heifers financially the right thing to do this year?" As the price of feeder cattle rises, the number of heifers kept for breeding should always go down or be zero. With the 10-12 year beef cycle, heifers kept in years of peak prices will produce calves that will be sold in years of much lower prices. John Lawrence at Iowa State did a herd simulation in 1996 and showed that by keeping more heifers at low prices and fewer at higher prices the herd netted an extra $4000/year (100 cow herd) when they used the "keep low, sell high" strategy.

No matter if your producers are going to raise their own heifers, buy them or if another producer is going to customize his business to specialize in raising replacement heifers, someone is going to raise them. This talk will hopefully address the major challenges and concerns of raising replacement heifers.

Selection

Producing and developing heifers is one of the most costly endeavors in the beef business. Studies show the average cost is between $700 and $1500 to produce a heifer from birth to calving at two years of age. This investment takes 5 - 6 years to generate a positive cash flow in your client's herd.

Records show that profitability is improved in herds with increased cow longevity because the herd comprises a low percentage of heifers. So, it is in everyone's best interest to select heifers that have an outstanding chance to remain in the herd for many, many years

Our herds on the Total Beef Herd Health Program ranked heifer selection/development as a high priority item. We discovered after utilizing many years of records that most of us select heifers exactly opposite of how we should. We learned that instead of finding reasons to keep heifers as replacements, we were better served by finding reason's NOT to keep a heifer. The reason we did the about-face is that when we found a reason (excuse) to keep a heifer, she generally did not stay in the herd a long time.

An example of this would be an extremely high weaning weight heifer that was extreme in her frame score. Sure, her mother was one of our best cows (½ British; ½ Continental), but this heifer would become a hard-fleshing, 1700# mature cow that would have a hard time getting re-bred on time. This is not our goal. Other "excuses" to keep her include: being out of the best cow in the herd, out of a superior AI bull, phenotypically appealing, the right color, etc.

After seeing our "excuses" heifers not stay in the herd for many, many years, we made a list of criteria that became our "automatic cull" rules. Heifers with ANY of the following traits are NOT kept for replacements.

1. Poor disposition.

2. Weaning ratio less than 90.

3. Frame score over 6.0.

4. Birth weight over 105#.

5. Dam MPPA less than 95.

6. More than 60% Continental genetics*

7. Not a crossbred/composite*

*Only a rule for commercial herds. Seedstock Continental herds may need heifers with greater than 60% Continental genetics

What we found when we went to this system of eliminating the outlier and problem heifers, is that we ended up with exactly the kind of herd we always wanted. We had a large group of moderate framed, easy fleshing, good disposition, crossbred heifers with similar genetic makeup that had almost no faults. We have used this system for about 15 years on our TBHH team herds, and our need for replacement heifers in subsequent years has fallen dramatically. Most of the list above is quite obvious once you change your mindset from "reasons to keep her" to the much improved "eliminate problems" mode.

One area I think we as an industry have totally neglected in recent years is heterosis. We are now chasing the "brass ring" of carcass quality at the exclusion of nearly every other trait. Heterosis is one of the most important aspects in cowherd profit. We must pick genetics for our environment, and then breed these heifers/cows to a bull that fits the market. In a 1994 study by Davis, et. al. at the Montana Agricultural Experiment Station, they compared the profitability of F1 dams (Angus-Hereford or Simmental-Hereford) to straightbred Herefords, 3/4 Hereford-¼ Simmental and ¼ Hereford-3/4 Simmental dams.

Their results showed that the F1 dams consistently yielded higher profits than the other dam breed groups. In fact, they showed nearly a $70/cow/year advantage for the F1 dams over the straightbreds. Another study by a purebred beef association showed a $117 advantage/year for a crossbred cow. This was a purebred association advocating crossbreeding, just like every breed used to do!!

As you assist your clients in selecting and developing replacement heifers, try the method outlined above to eliminate the problem heifers, and see cow longevity increase while their herds become much more uniform and profitable.

Development/nutrition

The goal is to have the heifer at 50-65% of mature weight at breeding time. Having heifers significantly heavier is not better, and having them significantly lighter generally equals poor reproduction.

Most of our herds want a cow with a mature weight of 1150 – 1250#. So these heifers should weigh 600 – 800# at breeding time.

If we have a spring born heifer calf that weighs 500# on September 1 (weaning date), she has approximately 240 days before she is bred (May 3) to calve February 10 the following year. If our target weight is 800#, this heifer needs to gain 300# in 240 days or about 1.25#/day.

Numerous research trails show that the heifer does not need to have a consistent weight gain from weaning to breeding. Many times it is cheaper to have heifers gain only 0.5#/day for the first 100 days and then gain 1.75#/day for the remaining 140 days. This needs to be evaluated on a case by case basis.

Many of our herds wean and background potential replacement heifers for 30 days in a traditional pasture or drylot situation but then put these heifers out on cornstalk ground or stockpiled pasture for a few months to let them "survive". I really believe that our traditional method of developing heifers on a high grain feedlot type ration is not conducive to developing these heifers to live the rest of their life eating grass and cornstalk residue. One of my clients that had the same philosophy told me one time that it is good for all of us to go though some "tough times" in our lives; our animals and us. I agree completely. If some heifers gain a bit of weight and look great during their "survival time" then they are telling us they really have what it takes to be a cow on your client's farm. Those that need a bit more feed and need an easier life are telling us that they really don't want to be cows on our client's farm.

Another test to see if your nutrition is on target is to see if you have heifers starting to cycle at 12 –13 months of age. Even on the limited nutrition program we use we see heifers cycling on a regular basis. That is very encouraging to me as to their innate fertility. If heifers are then developed properly after this time you should see most all of your heifers cycling 2-3 months before breeding

Health

You should develop a herd health calendar for all of your herds. Be sure to get two doses of MLV IBR-BVD into the heifers at least 30 days prebreeding.

Fertility

On many farms, beef heifers are looked at as a burden rather than a blessing. Remember, the only reasons to keep replacement females are (1) to improve the quality of the herd and (2) to improve the profitability of the herd. Heifers should NOT be kept for replacements because "we've always done it that way"!

The main reasons heifers are a burden on many farms are due to:

1. dystocia rates with first calf heifers

2. poor fertility of nursing 2 year olds.

To solve the first problem (dystocia), it should be the goal to breed all heifers via Artificial Insemination (AI) to proven calving-ease bulls. These would generally be Angus (red or black) sires in the top 10% of their breed for calving ease and low birth weight.

Heifers respond very well to various methods at estrus synchronization. This greatly reduces the time spent heat detecting and gives very acceptable conception rates. For heifers, the MGA- Prostaglandin Method is the "gold-standard" at this time. MGA is fed for 14 days at 0.5 mg/head/day, and 17-19 days after the heifers are off MGA, an injection of prostaglandin is given. Heifers generally show estrus in 48 – 72 hours.

We consistently have producers detect 90-100% of heifers in heat in a two day window, and conception rates average 60-70% on this breeding. If we have poor results, it is usually due to one or more of the following reasons

1. Less than 5 heifers in the group to be synchronized.

2. Heifers in poor body condition score at breeding (BCS <5)

3. Heifers overconditioned at breeding (BCS >7)

4. Heifers losing significant weight near breeding time

5. Heifers implanted at less than 45 days of age or received multiple implants

6. Heifers given initial MLV IBR vaccine (injectable) less than 30 days before breeding

For small herds where a producer would only keep a few heifers each year, you can solve problem #1 by combining the heifers from more than one herd to make a larger group. Working with the owner concerning heifer development solves the other problems.

The problem of poor fertility in nursing two year-olds can be solved by the following guidelines

1. Select the right type of heifers as outlined earlier

2. Breed the yearling heifers 21 days before the cowherd

3. Only breed yearling heifers for 42 days

4. Have heifers in Body Condition Score (BCS) 6 ½ - 7 at calving to insure a rapid return to estrus post calving.

The reason for breeding heifers 21 days before the cows is for, (1) better observation at calving, (2) gives heifers an extra cycle to get breed when they are 2 year-olds that are still growing, and (3) less disease problems when heifers calve before cows.

The reason for only breeding heifers for 42 days is that if we breed for 65 days (as we do with the cows), a heifer calving in the last 21 – 23 days of the calving season is at a distinct disadvantage in getting rebred compared to the earlier calving heifers. (See enclosed graphic for explanation.) A late calving heifer becomes either (a) a late calving cow or (b) an open cow. Which of these options is good? Neither: of course.

If a 15 – 17 month old heifer is open at pregnancy check, she can be implanted, fed and in 100 days be sold for choice beef price. If any female is open, it is best from a profit standpoint for it to be a yearling heifer. It is much better to have an open yearling heifer than a late-calving two year-old.

Precalving BCS is the most important factor in having an acceptable rebreeding rate in first calf heifers. In a study by Spitzer, et. al., 240 primiparous cows were calved in BCS 4, 5 or 6 and birth weight, dystocia score and subsequent fertility were studied. As BCS increased, calf birth weight increased slightly but dystocia score remained the same across all three groups. The most striking difference in the groups was with regard to fertility. The percentage of cows rebred in a 60 day breeding season for BCS 4, 5 and 6 was 65%, 80% and 96% respectively. This clearly shows the need to have heifers in very good BCS prior to calving if we expect an acceptable number to be rebred for the next calving season

Proper selection and development of replacement heifers are integral aspects of a successful beef business. This success is dependent on numerous additive factors where the herd health veterinarian can provide objective advice. Adding this service to your veterinary business can ultimately improve your client's business and your business.