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Raising Beef Replacement Heifers
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Raising Beef Replacement Heifers


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  • 1. Replacement Heifer Selection and Management C. P. Bagley, Professor and Head Department of Agricultural Sciences Texas A&M University- Commerce and R.R. Evans, Professor.* Mississippi State University The livestock inventory of Mississippi estimates a herd of approximately 1.4 million head, with about 750,000 beef cows. The southeastern part of the United States is known as a beef cow-calf area, selling calves at weaning to stocker and backgrounding operations in other areas of the country. Some estimates are that approximately 90 percent of all male beef calves (steers and bulls) are sold before reaching a weight of 500 pounds, indicating how strongly Mississippi favors cow-calf production. To remain profitable, cow-calf producers must embrace a total management strategy that includes genetic improvement, animal selection, and nutrition. Critical to any sustainable cow-calf production program is the selection and development of replacement heifers. Lifetime productivity of the beef cow herd is altered positively or negatively by genetic potential and the treatment a heifer receives from birth until she
  • 2. enters the cow herd. Generally, replacement heifers will be evaluated for their potential as brood cows approximately four times by the time they are 3 years old. These selection points include weaning, prebreeding, postbreeding for pregnancy, and when her first calf is weaned. This publication discusses the management of replacement heifers as part of a self-sustaining cow-calf operation or the raising of replacement heifers for sale. This publication also discusses five major areas of replacement heifer management and evaluation, including: 1. Selection criteria; 2. Age at first breeding; 3. Management from weaning to breeding; 4. Management from breeding to first calving; 5. Rebreeding for her second calf. The selection of high-quality replacement heifers is important to economic stability. Replacement heifers are your future. The cost of selecting and developing high quality replacement heifers is about the same as developing a poor-quality heifer. The major management difference in producing low- or high-quality animals is the return on the investment and profitability of the producer. *R.R. Evans is a professor of animal science with Mississippi State University. Selection Criteria There are several factors producers must consider in selecting heifers. One of the first criteria is breed preference. Breeds represent a color preference and color pattern, general temperament types, mature size, and multiple other factors that each producer must consider in selecting a breed. An old and accurate statement is that "there is more difference within a breed than there is between breeds," because when breeds are compared, averages are discussed. When individuals within a particular breed are discussed, extremes are evaluated. An individual producer must select the animal or animals that possess the strengths that offset the general weaknesses that he identifies in his herd. There are bulls that possess the traits needed for genetic improvement within more than one breed of cattle. A producer will generally do a better job of managing a breed that he "likes." Producers must select traits that individuals possess, rather than using the old method of selecting "X" breed for calving ease, milking ability, or whatever trait is needed and commonly associated with that breed. More importantly, a producer must have in mind a cow type that can produce a terminal (slaughter) animal that satisfies market requirements for carcass weight, quality grade, and yield grade. Industry standards for carcass animals, as outlined by the National Cattlemen's Association, are for hot carcass weights of not less than 550 and not more than 850 pounds. Discounts may occur for carcasses above and below these weights. Terminal sires that provide 650- to 750-pound hot carcass weights are preferred. These carcasses
  • 3. should quality grade between Select and low Choice and yield grade 1, 2, or 3. Terminal animals need to be medium to heavy muscled, have adequate bone and be a frame score 4.5 to 5.5, and have the ability to marble. Carcasses that "fit the box" will return a premium to the producer. Boxed beef and formula buying are current industry standards. Frame size, carcass weight, excessive finish (fat), and marbling ability must be major considerations in selecting and breeding replacement heifers that will make up the future cow herd. Expected Progeny Differences (EPD's) are available on most major breeds of cattle. EPD's are good predictors of an animal's genetic potential for production. An estimate of an individual's birth weight, weaning weight, yearling weight, milking ability, and, in some cases, carcass quality can be calculated from the EPD's of an individual's sire and dam. The EPD will compare an individual's genetic potential within his or her breed of cattle (e.g., Angus to Angus, Hereford to Hereford). Presently, there are no reliable EPD's for crossbreeds. With time and more animal records, crossbreed EPD's will likely become a reality. It is known from experience and common sense that breeding two individuals of different breeds with desirable EPD's generally will produce a calf that is at least an average of the EPD's of its parents. When different breeds are crossed, heterosis or hybrid vigor usually produces an animal that is superior to either of the parents. Producers sometimes select for extremes, which may not always be the best choice with EPD's. When producers select for small birth weights (zero or negative weights), they assume the average of the progeny of that bull will be his breed average (or below) for birth weight. Generally, these low-birth-weight calves will also wean lighter than will the calves from bulls with positive (+) EPD's for birth weight. With few exceptions, large weaning weights and yearling weights also equate to above average birth weights. There is validity to the old cattlemen's saying that a live small calf is worth more than a dead big one. Selling maximum pounds of calf is the objective of most producers, and it is recommended to select bulls with larger weaning and yearling weight EPD's for mature cows. Small birth weights are desirable for first-calve heifers, but not necessarily desirable for mature cows. Be aware that selecting for extremes in milking ability (EPD's of more than 20 pounds) must be accompanied by a higher plane of nutrition to achieve this higher milk production level and for cows also to rebreed. Average nutrition and management for cows with high milk production ability result in big calves at weaning but a high percentage of open cows. If feed is limited, cows will produce milk first and then rebreed. Heifers must be structurally correct, possess length and depth of body, femininity, and sound feet and legs. Replacement heifers should also be selected out of cows that do not have teat and udder problems. A complete, permanent set of records, in conjunction with a permanent identification system (tattoo, ear tag, brand, or a combination of these), is imperative in selecting replacement heifers. These records should provide information on an individual's sire and dam, birth date, birth weight, weaning weight, and yearling weight. Keep a permanent record on every producing individual in your herd and on those culled animals that still
  • 4. have offspring producing in the herd. This allows producers to identify and select females with a long record of above average production in their backgrounds. Without records, selection is a guess. Select bulls with a large scrotal circumference. Research shows that the daughters of bulls with a large scrotal circumference tend to reach puberty at an earlier age than do the daughters from bulls with smaller testicles. To maintain a profitable and sustainable beef operation, you must use all available information to select heifers from cows and bulls that have the genetic potential to produce at profitable levels and then to manage these animals to realize that genetic potential. Select heifers using EPD's from the sire and dam and production records from sound-uddered cows that have consistently weaned above average calves over their productive life. All genetic progress in a closed cow herd is made through bull selection or replacement heifer selection. Selection At Weaning Fat is a pretty color. It is also an indicator of the dam's milking ability. Select heifers from cows that give milk as evidenced by high weaning weights. This economically important trait is passed on to a cow's offspring and can be maintained or even increased in her calf by breeding to sires with high EPD's for milk. Make sure that these cows have small teats and well-attached udders. Balloon teats and poorly attached udders are undesirable, but highly heritable traits, and both are reasons to cull a cow from the herd. In an effort to maximize weaning weights, some producers creep feed their calves. Take care when selecting heifers that have been creep fed heavily. Make sure you are selecting for milking ability in the dam and not the calf's ability to convert feed efficiently. Heifer calves that are heavily creeped may be overfinished and have fat deposited in their udders at a young age. This fat may cause her to have a lowered milk production level throughout her life. Heifers out of extremely heavy milking cows may also have this problem. Heavy creeping with grains generally causes most of the fatty udders, but some producers have also reported fall-born heifer calves becoming too fat when given access to a good-quality creep grazing area. Fatty udders can be reduced by weaning heifers early, limiting access to creep, or breeding cows to a growthier, larger-framed bull. Excessive finish at weaning is less of a problem in larger-framed than in the smaller- framed cattle. If possible, you should manage heifer calves separately from bull and steer calves when using a creep system. Getting calves too fat before weaning is a sign your nutrition program is better than the genetic potential of the calves you are raising. Either reduce your nutrition program or breed to a larger-framed bull. Select replacement heifers from those born in the first part of the calving season. The dam of replacement heifers should have produced a calf approximately every 365 days, and those calves should have been in the upper 50 percent of the cow herd for weaning weight. Because these heifers are older, they will be larger and should breed readily
  • 5. because they will be more mature at the beginning of the breeding season. Cows with a consistent record of early calving usually pass this fertility level on to their daughters. Coupling this female selection characteristic with selecting bulls with large testicles will improve fertility in your females. Adjusted 205-day weights is another tool that can be used to select replacements in crossbred herds and can be used directly to compare heifers within a herd. This adjustment uses actual weaning weight, subtracts the calf birth weight, and divides this "net" weight by calf age in days to give average daily gain (ADG). This ADG figure is multiplied by a factor of 205 and the birth weight added to that sum, and adjusted for sex, to equate all calves to 205 days of age. Young cows receive an upward weight adjustment for age until they are 5 years old. Adjusted 205-day weights allow you to compare the production ability of young cows (2-, 3-, and 4-year-olds) to the production records of mature cows. Generally the heifer calves weaned from young cows are smaller due to their sex and the age of the mother, but genetically they are superior to the average of the cow herd if better quality bulls are being used. Weaning To Yearling At the end of the yearling development stage, select heifers that continue to exhibit the desired phenotype and have expressed genetic ability to grow by reaching the target weight set for yearling heifers in your herd. For a heifer to breed at 13 to 15 months of age and calve as a 2-year-old, she must achieve approximately 70 percent of her mature weight by the start of the breeding season (i.e., 700-pound yearling/1,000-pound mature). This heifer must have the genetic potential to grow past weaning and then be fed to achieve this breeding weight. Observe heifers closely before the breeding season to determine the percentage of heifers that are cycling. Identify and record cycling heifers. Heifers that exhibit puberty at a young age have the best chance of breeding early and being productive for many years. Pelvic Measurements There is no guarantee a heifer with a certain pelvic measurement will calve without any problems, but these measurements can be used to cull heifers with smaller pelvic measurements. Heifers with relatively small pelvic measurements have a greater potential to experience problems at calving time. Average pelvic measurement figures are 13.5 cm high, 11.5 cm wide or about 155 to 160 cm-squared as a minimum for a 12- to 14-month- old heifer. Pelvic measurements can be useful in predicting the size of calf a heifer is able to deliver without assistance. Example: (160 cm-squared) / 2.1 = 76-pound calf without any problem.
  • 6. Heifers with less than 160 cm-squared are more likely to have trouble at calving time than those meeting this minimum standard. Some veterinarians are now evaluating the reproductive tracts of yearling heifers, via rectal palpation, and their reproductive tracts scored against a standard. Tracts are evaluated for size, tone, and ovarian activity. This examination identifies heifers that have and have not attained puberty. Again, this scoring system provides another tool in selecting your beef replacement females. Yearling To First Conception Give consideration to the selection of a bull likely to produce smaller birth weight calves for breeding to first-calve heifers. Selecting a small-birth-weight EPD bull will reduce the risk of heifers having difficult births. There is a high correlation between sire birth weight and calving difficulties in cows and heifers. Most breed associations have EPD's for birth weight and calving ease available on their bulls. Bulls that produce small calves at birth have been identified and should be used for first-calve heifers. Breeding heifers to bulls of a similar breed type and mature size will help lessen the chance of calving problems (e.g., Angus bred to Angus, Angus-Hereford crosses to English bulls, etc., not a Continental bull to English-bred heifers). A Continental bull bred to mature cows of a smaller breed type would be allowable, but first-calve heifers are too small to calve consistently unassisted to these larger-framed bulls. Pregnancy check heifers 45 days after the end of the breeding season. Producers with two calving seasons must decide if open heifers are a good risk to put into fall (spring) calving herd or be sold. Approximately 3 to 5 percent of heifers are sterile or subfertile. If this open heifer is sold in the early fall after her first breeding season, she will be bought as a feeder heifer and be worth more money than as a cull cow. Cost figures for annual maintenance of a beef cow in the South range from $300 to $400. Assuming a median figure of $350, or approximately $1 per day, keeping a heifer to calve 6 months later than her contemporaries would add approximately $175 to her cost as a replacement animal. If the heifer weighs 900 pounds at 18 months of age and would be worth $.65/pound, she would have a salvage value of $585. If you add the extra $175 maintenance cost to this $585 salvage value, keeping the heifer would make her have a cost of $760 by the time she calves. A bred heifer could be purchased for $750 to $775. The cost of the bred heifer will be about the same as the heifer you kept, but you know the bred heifer will breed. If you think your genetics are better than you can buy, then you might consider saving your open heifers. If you calve only one time per year, the option is clear; sell your open heifers and purchase bred heifers. If a heifer is given a second chance to become pregnant in the fall (spring) cow herd, the heifer must breed or be culled immediately. A 6-month reprieve early in her life may be justifiable, but no longer. First Calving: Birth to Weaning
  • 7. Heifers with above average milk producing ability demonstrate this characteristic in their first lactation. Weaning weights from calves born to heifers will usually be below the mature cow herd average. Do not compare the weaning weights of calves born to heifers to those born to cows. Compare weaning weights within age groups: heifers to heifers, cows to cows. Using one of the weaning weight adjustment packages available will allow you to compare the entire herd. Just remember, a heifer usually will not wean her heaviest calf until she is 5 years old. Producers have heard that the heifer's first-born calf was small at weaning because it was born late in the season. Odds are that the heifer's next calf will also be born late and have a low weaning weight. At pregnancy checking time, if a heifer is bred to calve late again, cull her unless she weaned an above average calf. Chances are good that late-calving 2- year-old heifers will be open next year simply because 2- and 3-year-old heifers generally breed back more slowly (slightly longer than 12 months between calves), or at best, have an even later calf. Management from Weaning To Breeding Heifers generally are weaned at 7 to 8 months of age (spring or fall calving). Before weaning, heifers should have received a complete preventative vaccination program sometime between 4 months of age and 30 days before weaning. This calf health program should be specific for the area, but a good general program would include IBR, BVD, PI3, BRSV, Pasturella, Leptospirosis (5-way), Vibriosis, the Clostridium complex (4- or 7- way), and a calfhood vaccination for Brucellosis. All heifers should receive a booster at weaning for all vaccines except Brucellosis. Replacement heifers need to gain 1 to 1.5 pounds per day from weaning time to breeding. Give heifers an adjustment period to heavier concentrate rations to avoid digestive upsets (2-week warmup) and have them on full supplemental feed (1 percent to 1.5 percent of body weight) by mid-November to the first week of December, or sooner if possible (August for fall-born heifers). Obviously, all weaned heifers will not weigh the same. It is not unusual to have a 100-pound difference in weight range within a group of heifers. All heifers do not need to gain at the same rate during the development period, since they have different initial weights. A 1 pound per day weight gain for 180 days would achieve the target weight of more than 700 pounds for the 550-pound heifer, but the 450-pound heifer would be too small (630 pounds)at breeding. Segregate heifers into weight ranges and feed accordingly so target weights are reached at the beginning of the breeding season while reducing feeding costs. Consult your county Extension agent, livestock specialist, veterinarian, or feed dealer for a properly formulated diet. Heifer calves previously dewormed in September or October can become heavily reinfected with internal parasites by mid-November to mid-December (depending on rainfall). Deworm your heifers again during the 30- to 45-day period after weaning, since these replacement heifers are young and have little resistance to internal parasites. Research shows that even well-fed heifers that are not dewormed can become heavily
  • 8. parasitized and perform poorly. Research also shows, even though feed was available to parasitized heifers, they would not eat or could not use the feed due to parasitism. While extreme parasitism can result in death in young animals, its usual symptom is poor performance. Another deworming for replacement heifers should occur 30 to 60 days before the breeding season. Grass is beginning to grow in early spring, and the grazing heifers can quickly become reinfected with parasites. During the fall, winter, and early spring in the South, the numbers of adult internal parasites are at their peaks in replacement heifers. Type I and Type II deworming agents effectively control these adult parasites. In review, heifers need to be dewormed before or at weaning, again 30 to 45 days postweaning (mid-November to mid-December), and a third time approximately 30 to 60 days before the beginning of the breeding season. The economics of deworming young cattle are simple. If you do not deworm, you run the risk of having a heifer too small to cycle and breed, and, in severe cases, even death. The objective of any parasite program should be to prevent parasitism, not treat it. An ounce of prevention, or $3 to $4 for a dewormer, may be worth more than a pound of cure. Fall-born heifers generally are weaned in June. Usually there is good forage available for these heifers. Their maintenance requirements are lower due to the weather (not as cold) and they are heavier at weaning (on the average) than are the spring-born calves. As a consequence, fall-born heifers need less concentrate (approximately 5 pounds per head daily) through early December. These heifers need to be dewormed in midsummer (July) with a Type II dewormer, which controls the inhibited stage larvae of the brown stomach worm. The brown stomach worm has developed the ability to go into an arrested or inhibited stage in midsummer in the South. After being picked up on grass while the heifers graze, these parasites then pass into the stomach or abomasum, where the larvae burrow into the abomasal wall and become inhibited. These inhibited or arrested larvae, remain in this developmental stage until cooler, rainy weather arrives. These inhibited larvae begin to enlarge rapidly just before maturing or "hatching out." These larvae are considerably larger than when they burrowed into the gut wall and this maturation process can cause extensive damage to the gut wall, if large numbers of parasites are involved. This damage to the secretory cells of the stomach wall can interfere with protein digestion for the remainder of the heifer's life. Deworm heifers again in mid- November before the fall breeding season. Again, have these heifers weighing 700 to 800 pounds at the start of the fall breeding season. A check weight on fall and spring replacement heifers between weaning and breeding should be helpful to make sure rate of gain is adequate to reach target weights. Age at First Breeding Breed heifers initially at 13 to 15 months. Heifers are large enough by this time, weighing from 675 to 800 pounds, and should have a breeding percentage of more than 90 percent. Placing selection pressure on heifers for reproductive efficiency will raise pregnancy rates quickly in the cow herd. Some Brahman cross heifers and Continental crosses do
  • 9. not cycle as early as predominantly English cross heifers, but a fairly high percentage (75 percent) of these large-framed crosses should breed at 13 to 15 months. Selection pressure for earlier maturity is being placed on Brahman cattle as well as selection for more moderately sized, earlier maturing Continental breeds. Producers should start the breeding season for heifers about 3 weeks before that of the cow herd. When heifers do calve, they will have an additional 3 weeks to repair themselves, which heifers will need before being bred for their second calf. For their second calf, these heifers would have the same breeding season as the mature cow herd. Calving 3 weeks earlier allows producers to watch these heifers more closely, since most calving difficulties occur with this group of females. To wean a consistent group of calves of approximately the same age and weight, most producers limit the breeding season to 65 to 75 days, with extremely intensive programs going to 45 days, and less intensive programs 90 days. Managing and marketing closely grouped calves is advantageous to producers in terms of better labor management and a higher price per pound at market. Management from Breeding To First Calving For replacement heifers to be of sufficient size to calve at 2 years of age, they should gain about 1 pound per day after conception. For example, a 750-pound heifer bred in early May that calves in early to mid-February and gaining 1 pound per day will weigh about 1,000 to 1,025 pounds at first calving. This weight at first calving should be approximately 85 to 90 percent of the expected mature weight. Many calving problems can be eliminated if heifers are of adequate size. Smaller-framed heifers may weigh 850 to 900 pounds at calving, but any smaller can be a serious problem. Before their first calf, heifers should receive a vaccination booster, which should include the Clostridium complex (4- or 7-way), Pasturella, BRSV, Leptospirosis (5-way) Vibriosis, IBR, BVD, and PI3. This booster will insure a high antibody titer in the heifer's colostrum milk. Also, bred heifers need deworming again in early winter between December and late January. Replacement beef heifers need to be in good body condition (5.0 to 6.0) at all times (see photos below). Body condition score (BCS) is a visual and tactile measure of external body fat. The values range from a low of 1 to a high of 9. A heifer with a BCS of 1 would be completely devoid of fat, basically a hide stretched over bone. This heifer is just before starving to death. A heifer with a BCS of 9 is extremely fat. Producers would not be able to see or feel the ribs or spinal processes. This heifer has excessive fat around the tailhead, flank, and brisket. Avoid these extremes. Ideally, heifers should be in a BCS between 5 and 6, which would have the heifer in "good shape." She should have a smooth covering of fat over her ribs, back, hooks, and pins. You would not consider this heifer fat -- just in good condition. Ideally, heifers should not lose more than one BCS after calving. One BCS point equates to about 100 to 125 pounds of external fat. Body fat is
  • 10. used by the heifer to provide energy during the calving process, to provide high quality colostrum for her newborn calf, and to allow her to produce adequate milk. Also, this extra body fat will provide energy to allow the heifer to initiate her estrus or heat cycle earlier after calving and to breed back sooner. There is little validity to the concept of holding back feed from heifers before calving to make the calves smaller at birth. This generally leads to a situation where the heifer and her calf are both weak at calving. While overly fat heifers are a problem, an undernourished heifer is the problem most often observed. Isolate heifers just before calving so they can be watched closely for signs of calving difficulty. Provide shelter for these heifers, but have an open view of the area. Have these heifers close to a holding facility in case of calving problems. You should expect that about 80 percent of the problems at calving will be in the first-calve heifers. Rebreeding a Heifer for Her Second Calf Educators have done a good job promoting the concept of calving heifers as 2-year olds, but have failed to tell producers that there is a cost involved. This cost is more feed and higher management levels if heifers are to breed back early and calve again as 3-year olds. The process of getting heifers to rebreed occurs before calving by allowing heifers to put on body condition and by maintaining as much condition after calving as possible. If the heifer is in poor body condition before calving, she will likely not rebreed or rebreed late in the season. Heifers calving in poor body condition (BCS 4 or below) will need substantial supplemental feed to maintain body reserves, and even then the conception rate on the group will be poor. The approximate order of energy partition for cows is to milk, grow, and rebreed; so the first sign of poor nutrition is a failure to rebreed. It is unlikely a growing heifer can eat enough to satisfy all her energy requirements and gain weight until well into the breeding season when her milk production declines. Your main objective should be to "maintain" good body condition (not less than BCS 5) with a minimum of supplemental feed until high-quality grazing is available. Use visual appraisal to evaluate your heifers before calving. Separate the heifers in better shape (higher BCS) from those in poorer body condition. Overfeeding well-conditioned heifers is a waste of money and has the potential to increase calving problems. The thinner heifers can use the extra feed to add body condition, which can increase milk production and rebreeding percentages. Keep a "balance" of required nutrients available to heifers at all developmental stages. These nutrients include energy, protein, vitamins, and especially, a good complete mineral mixture. If heifers are on a salt limiting feed (hot mix), make sure a complete mineral is included in the hot mix. Nutrient balance is important at every developmental stage, but none is more critical than a first-calve heifer.
  • 11. Finally, rather than being concerned with only heifers, be concerned with first- and second-calve heifers (the name should be changed from first-calve heifer to first- and second-calve heifers). Cows continue to grow until they are 4 or 5 years old. Nationwide, almost as many 3-year-old cows that calved initially as 2-year-olds are as open as 2-year- olds. Producers frequently feel that they do not need to manage 3-year-old cows as intensely as they do 2-year-olds, but the nutrient requirements are almost as high for the 3-year-old cow. When 3-year-olds are grouped with mature cows, the younger cows frequently get pushed away from the feed. Keep the 3-year-olds separated from mature cows whenever possible, particularly during the winter feeding period. Managing 2- and 3-year-old cows as a single unit is a better management technique than mixing the 3-year- olds with the mature cow herd. Summary The proper development of beef replacement heifers requires a higher level of management than does managing the mature cow herd. Whether raising your own replacements or raising replacement heifers to sell, there are several key factors that are crucial for the development of productive, high-quality females. These factors include: • Do not get calves too fat at any time between birth and their initial breeding season. • Heifers should weigh about 700 pounds by 13 to 15 months of age to calve initially as a 2-year-old. • Breeding season for heifers should start 3 weeks before the normal breeding season of the mature cow herd. • After the breeding season, heifers need to continue gaining at approximately 1 pound per day so they will calve at a weight of 1,000 to 1,050 pounds. • Have heifers in good body condition before calving to increase rebreeding rates and calf weaning weights. • At calving time, keep heifers close and watch carefully and frequently. Most calving difficulties will occur in this group of 2-year-olds. • First- and second-calf heifers have higher nutrient requirements than the mature cow herd. Young females are still growing while producing milk and require a higher plane of nutrition.