Several managerial practices increase productivity within cow-calf herds when they can be implemented economically and practically. These practices are mostly associated with reproduction, as improvements in herd fertility generally offer potential for increased profitability in cow-calf operations. They include a restricted breeding season, identification of the optimal calving season, a good heifer replacement program, heifer reproductive tract scoring, proper nutrition, good herd health, bull breeding soundness examinations, crossbreeding, and maintaining good records. Other management practices associated with increased beef herd profitability include decreasing unit cost of production, use of growth promotants in calves, internal and external parasite control, improved calf management, management-intensive grazing, preconditioning of calves, and having a marketing plan.
In most regions of the world, there is an optimal period for females to calve, suckle, and rebreed. This period is mostly related to nutritional opportunity, although other environmental factors such as cold or heat stress and parasite populations may play a role. Producers have traditionally aimed for females to calve at this optimal period because they tend to breed back faster, and their calves are more likely to thrive, than those that calve at less opportune times. Benefits of restricted breeding seasons (65–80 days) include enhanced production potential, favorable environmental factors, a concentrated calving season and more homogeneous calf crop, increased opportunities to perform prebreeding management procedures and monitor nutrition, improved female replacement and culling procedures, and the ability to detect problems early, using herd pregnancy diagnosis and breeding season evaluation. (Also see Cattle.)
The longterm goal is to develop a beef herd of uniform, low-maintenance cows that thrive in their given environment. This goal is strengthened by having a restricted breeding season in which open cows are culled from the herd. Often, these cows are too big, have too much milk production, or lack inherent fertility compared with the cows that are pregnant year after year. In herds that are years away from this goal, instead of simply calling cows pregnant or open, cows should be sorted by projected calving date and body condition score (BCS). The herd pregnancy diagnosis (HPD) represents an important starting point for beef herd diagnostics and advice and is a pivotal component for informed decision making. It allows analysis of group patterns for problem solving (breeding soundness evaluation, see Breeding Soundness Evaluation), as well as sorting of animals into groups for specific purposes such as strategic feeding, calving supervision, culling, or rebreeding. HPD facilitates the selection of replacement females and culling for infertility.
Breeding Soundness Evaluation
Reproductive performance is influenced by many factors including sire fertility, herd health aspects, and opportunities to mate. Breeding soundness evaluation is a technique for assessing the reproductive performance of the cow herd. It includes obtaining relevant information, analysis and interpretation, and recommendations for improvement. One measure of reproductive performance is the number of exposed females that actually raise a live calf. Other valuable information may be obtained from an analysis of the distribution of pregnancies (and calvings) that resulted from a particular breeding season. This distribution may be studied on the basis of timing (eg, 21-day estrus periods), breeding groups, female age or parity, nutritional opportunity (eg, BCS), etc. Such analyses provide the basis for evaluation of either the breeding or calving season. For evaluation of the breeding season, good records must be obtained at the time of pregnancy testing for the subsequent analysis to be valid.
Because reproductive performance is an important economic trait in the cow herd, the reproductive capabilities of breeding bulls assume great importance. The best assurance that a bull is likely to be fertile is a successful breeding soundness evaluation. (see Breeding Soundness Examination of the Male.) A rule of thumb for bulls is that they can breed ~1 cow/mo of age in a breeding season of 65–80 days. For example, a 38-mo-old bull that passes his BSE should be able to breed 38 cows in 65–80 days. This rule is effective for bulls about 14–50 mo old, with 50 cows/bull being the maximum.
Cull Cow Selection and Management
Culling of cattle in a beef operation usually implies removing those that cannot meet or maintain performance and economic criteria for the herd. Other reasons may include physical or temperament problems in animals, as well as judicious culling during periods of environmental hardship or economic necessity. The judicious removal of nonperforming females is also important in maintaining or improving herd fertility. However, the assumption that cull cows are necessarily unproductive may not always be correct; recent surveys indicate that ~43% of cull cows in the USA are pregnant at the time of survey. In addition, “open” females are not necessarily infertile. Identification of appropriate candidates for culling is critical and should be an important component of pregnancy testing.
Nutrition is the most important limiting factor of beef herd reproductive performance. An understanding of the principles underlying the nutritional management of breeding females is necessary, including a working knowledge of the different energy measuring systems that are commonly used and their applications for different classes of animals, activities, and feedstuffs. (see Cattle.) Increasing stocking rate tends to cause increased gain per unit land area but can result in decreased gain per animal. The key is to have these 2 factors in balance so that pasture land is optimally grazed and gain per animal is adequate. Overgrazed pasture is detrimental to the environment and can severely reduce gain per animal.
Nutritional requirements vary throughout the year. The most critical periods for reproduction are immediately precalving, when fetal growth is maximal along with lactation preparation, and early postcalving, when maximal lactation is combined with the need for rebreeding. (Also see Cattle.)
Environmental conditions can strongly influence the nutritional requirements and intake of cattle. For example, cold weather increases energy needs, whereas hot or inclement weather can reduce foraging opportunity. The quality and quantity of range forage varies greatly throughout the year and between years, influenced by moisture, soil fertility, plant species, and grazing pressure. Seasonal changes in the nutrient density of rangeland forages are mainly associated with the degree of plant maturity. In general, the greatest nutritional value of plants develops before maturity. Good nutritional management involves matching, as far as possible, the nutrient requirements of cows and nutrient density of the pasture by careful consideration of factors such as the types of animals involved, stocking rates, plant species available, season of grazing, fertilization, and grazing methods used.
Body Condition Score
Accurate and timely determination of nutritional status of grazing animals represents a challenge for beef producers, because many variables can influence a cow's response to a given level of nutrition. The use of a BCS is an effective indirect method for determining nutritional status in breeding females. The BCS represents a subjective assessment of body fat (or energy reserves) that is strongly related to female reproductive performance. BCS, and changes in BCS, appear to be more reliable indicators of nutritional status than is body weight or changes in body weight, which can vary with gut fill and pregnancy status. In addition, BCS can often be assessed more conveniently than body weight can be measured. BCS is both repeatable and accurate in experienced hands. It is best done through visual appraisal, reinforced by palpation of body regions most likely to demonstrate fat deposits. Group observations of BCS made from a distance when animals are in the pasture or paddock are less accurate than those made when animals are nearby in the pen or chute.
BCS varies throughout the year and should be monitored regularly. In the 1–9 BCS system widely used in North America, the reference standard for beef females is a BCS of 5, which represents an average, moderately fleshed cow that is neither fat nor thin. However, the BCS for optimal female efficiency varies with breed and operation and may be higher or lower. In general, cows should calve when they are between condition scores 5–6 (heifers at 6–7) and then regain the weight lost at calving or gain slightly until breeding. It generally takes ~2 mo to gain 1 score (75–100 lb [34.1–45.5 kg]) under pasture conditions. Care should be taken not to rely on averages, because these can mask variations that might adversely affect herd fertility.
The BCS of females at calving can provide much information about their rebreeding prospects. However, assessment of BCS at this time provides a relatively short length of time in which to meet targets if cows are too thin. Assessment of BCS in females at breeding should provide the most accurate prediction of herd fertility because it is done just before the predictive event. The disadvantage is that there is no opportunity to correct significant shortfalls in time to affect the current breeding season. Assessment of BCS at the time of pregnancy checking has the advantage of not requiring a separate animal handling. It also allows considerable time to remedy obvious deficiencies before calving and subsequent rebreeding. The disadvantage is that, although it can provide clues to explain current pregnancy patterns, it is too late to remedy them. The ideal time to assign BCS to cows is ~2–3 mo precalving. This gives ample time to move cows to an optimal precalving BCS, because BCS at calving is highly correlated to herd fertility. It is best if someone other than the owner (eg, veterinarian, extension specialist, etc) does the BCS evaluation of the herd, because the owner sees the cows every day and is less likely to see changes.
Health and Production Management Program
A cost-effective herd health and production management program is essential for the economic viability of cow-calf operations. Such programs vary by region, relative economics, perceptions, and opportunity. A good herd health program manages risk of disease and lowered productivity at a number of levels, including considerations of biosecurity, nutrition, and the judicious use of biologics and parasiticides.
One starting point for such a program is to identify current production losses by comparing the performance of the particular herd with relevant standards, eg, from regional or national surveys, which can also provide an economic estimate of losses.
The major disease risks for a given herd, along with appropriate preventive measures, should be established in consultation with herd owners. The best times for herd intervention must be identified. These often coincide with other managerial tasks and can be synchronized to minimize herd disruption and labor costs. One approach is to devise a herd-health “calendar” in which the health events are coordinated with major operational events. Interventions for a particular herd vary based on factors such as available labor, normal herd working dates, calf weaning dates, calf management practices, and previous disease problems.
Prebreeding vaccinations should be completed ~4 wk before the start of breeding and should be based on local patterns of disease and any state or national requirements. Replacement females should be vaccinated with the same vaccines given to mature females before breeding.
Precalving vaccinations are intended to protect the newborn calf through colostral transfer. The most common immunizations are those that offer protection against some of the infectious causes of neonatal calf diarrhea. Others are based on local patterns of disease.
Preweaning is an important intervention that can help prepare calves for the stress of weaning and reduce the possibility that such stress will compromise the efficacy of biologicals. Common vaccinations include the clostridials and bovine respiratory disease complex (BRD). A broad-spectrum anthelmintic should also be given at this time, because calves that have been on pasture have almost certainly been exposed to internal parasites. At weaning, a second vaccination should be given for those products recommending 2 injections. Modified live virus (MLV) products should be given at this stage. Another clostridial vaccination is not indicated if calves were previously vaccinated at working and preweaning. For areas where brucellosis is under regulatory control, appropriate heifer vaccination should be done within the age ranges stipulated.
Bulls should receive the same vaccines as the cow-calf herd, with some exceptions. Bulls should not be vaccinated for brucellosis. Also, the trichomoniasis vaccine currently approved for use in the USA is not approved for bulls. Caution is advised with MLV infectious bovine rhinotracheitis vaccines, because bulls may recrudesce this virus and shed it in semen. Always ask the manufacturer's technical services veterinarian if this is a concern. Also, if MLV infectious bovine rhinotracheitis vaccine is used, semen shipment to other countries may be jeopardized.
Management of the calving season is critical to optimizing the weaned calf crop. Research indicates that 57% of mortality is seen in the first 24 hr and 75% within 7 days of birth. In addition, there are significant risk factors for increased calf morbidity at the time of calving that can lead to increased mortality and decreased calf performance. Factors to consider in calving management include dystocia management (of primary concern in replacement heifers), calving environment (including ambient temperature), passive transfer, and cow-calf pair management. (see Cattle.) A visit to the farm or ranch ~4 wk before the onset of the calving season provides the opportunity to evaluate the preparations made by the producer and to recommend any changes.
Keeping records on calving ease and morbidity and mortality incidence allows for analysis of risks and risk groups and detection of any increased incidence of disease. At least one additional visit should be made to the farm 2–3 wk after calving has begun to assess the management and environment. Morbidity and mortality incidence levels may be established; if these are exceeded, the veterinarian should be called and an investigation begun.
The most common cause of calf morbidity in the neonatal period is diarrhea. (see Diarrhea in Neonatal Ruminants.) It is generally not possible and many times not important to differentiate diarrheas associated with different etiologic agents. Control for pathogenic agents of neonatal diarrhea involves segregation of sick animals from the healthy nursery to decrease environmental contamination and transmission. In addition, Escherichia coli and Salmonella control involves biosecurity rules to prevent the purchase and introduction of new calves or cows during the calving season. Sick calves should be isolated quickly to prevent further environmental contamination. Once the environment is contaminated, moist, cool conditions allow survival of infectious agents for an extended period. Cryptosporidia are especially suited to survival in the environment, and prevention of contamination in the healthy nursery is critical. Commercial vaccines for rotavirus, coronavirus, E coli and Clostridium perfringens types B and C may be given to cows and heifers before calving to elevate specific immunoglobulin levels in colostrum. An initial vaccination and booster followed by a yearly booster is generally required. If a booster vaccination is needed, it should be given at least 2 wk and not more than 6 wk before calving. Clinical trial data are not consistent; some trials report no effect, whereas others report significant decreases in morbidity. Vaccination is likely a useful adjunct to proper management in controlling neonatal diarrhea, but the key is environmental control.
An excellent environmental control program is the “Sandhills calving system” developed at the University of Nebraska. In this system, pregnant cows are wintered in an area separate from the calving area. When the first cow calves or is about to calve, the entire herd is moved to the first calving pasture. Cows stay here for 2 wk; after this time, all cows with calves stay on pasture 1 while all cows yet to calve move to pasture 2. After 1 wk on pasture 2, all cows with calves stay and all pregnant cows move to pasture 3. This continues for the next 6 wk. Cow-calf pairs can be combined when the youngest calf in the group is 4 wk old and at low risk of diarrhea. This system assures that each calf is born into a clean environment, so disease transmission is minimal to nonexistent. Herds that had severe morbidity and mortality from scours before using the system may have almost no health concerns after its adoption.
In this and in all calving systems, heifers should be wintered and calved separately from adult cows, because heifers have lower immunity to pathogens than cows.
Castration and Dehorning
Castration of male calves in early life (before 4 mo of age) is likely to be less stressful to calves than castration performed later when testicular size is dramatically increased. In addition, early castration raises less concern about humane treatment. A number of methods may be used, including the open surgical technique, the use of rubber rings, and the Burdizzo method. Calves castrated surgically initially exhibit more agitation than calves castrated with rubber rings, but both groups resume normal behavior soon after the operation is completed. Dehorning early in life is also less stressful than when performed later when horns have increased in size. Horns are mostly a problem for the feeding period (ie, horned calves require more bunk space), and they may cause bruising in penmates. Such problems are best managed by polled breeding or early dehorning.
Individual identification of cows and calves allows for selection based on performance as well as for tracing the animal to its herd of origin to track or contain disease. Plastic ear tags are the most commonly used method of individual identification. Branding as a method of herd identification is coming under increasing scrutiny for product quality and animal welfare reasons. Commercial products are currently on the market that allow individual electronic identification. Such initiatives may eventually replace current identification systems.
Vaccines are available for viral and bacterial respiratory pathogens. Residual passive immunity in young calves may limit the detectable antibody response to vaccination at an early age but use of MLV infectious bovine rhinotracheitis and bovine viral diarrhea vaccines stimulates a significant cell-mediated immune response in calves with residual passive immunity to these diseases. Specific age recommendations for initial vaccination are made by vaccine manufacturers. Calves vaccinated at branding time may be sensitized to the antigens and respond with an anamnestic response when given another vaccine at arrival in the feedlot. Recommended vaccination programs include clostridial and viral respiratory vaccination at the time of branding. A number of “value-added” calf programs have been initiated, some of which require a vaccination program at branding time. Pneumonia incidence is typically low during the summer grazing periods, making clinical effectiveness of a vaccination program against respiratory disease difficult to demonstrate. Primary sensitization to increase subsequent vaccination response preweaning may be the major benefit of such a vaccination program. A repeat vaccination against viral respiratory agents is often administered to calves before weaning. Vaccination for Mannheimia has been recommended for inclusion in some preweaning or weaning vaccination programs as well.
Infectious keratoconjunctivitis (see Infectious Keratoconjunctivitis) can be a significant problem in suckling calves, and control can be difficult. Vaccination has shown variable results. Challenge with a homologous strain after vaccination may provide some level of control, but challenge with a heterologous strain creates little protection.
Use of hormonal implants as a management practice for suckling calves may increase weaning weights by 3–5%. Optimal response is seen in healthy calves with adequate nutrition. Heifers kept for breeding should not be implanted if <45 days old, and bulls should never be implanted. (see Growth Promotants and Production Enhancers.)
Egg burdens of calves are typically low at spring branding but may rise significantly by midsummer. Deworming of cows in late spring may lead to increased weaning weights in calves. Studies examining the effects of deworming calves only at branding have been few and results were inconsistent—some showed positive effects, while others found no effect. Deworming of calves in addition to cows in late spring appears to confer minimal additional benefit. External parasites of cattle are estimated to be an important cause of economic loss as well. Studies have generally shown a weight gain of 10–20 lb in suckling calves when fly control is provided. The most common method of fly control is the use of insecticide-impregnated ear tags. With the widespread use of pyrethroid insecticides in ear tags, emerging resistance has become a problem, so rotating to organophosphate or endosulfan tags can be helpful. Insecticide sprays and back rubbers can also be effective (and less expensive), but cattle must be forced to use them.
Suckling beef calves are generally not supplemented during the summer grazing period, when milk and an increasing intake of forage provide their diet. Deficiency of trace minerals may be a concern in some areas. Proper nutrition of the herd before calving should provide the calf with adequate reserves at birth. Subsequent supplementation is difficult, however, as trace mineral mix intake is sporadic at best in calves. Creep feeding may increase the reliability of intake, but it is an expensive substitute for available forage and the response is highly variable. Creep feeding for 3–4 wk before weaning may be an effective way to reduce stress and disease at weaning. (Also see Cattle.)
Weaning is stressful because the calf is removed from its dam and has to adjust to a different diet and environment; population density is increased, leading to potential for increased disease exposure and transmission. Management procedures should aim to minimize stress to calves while ensuring they are in sound condition nutritionally and immunologically. Castration and dehorning should be performed well before weaning. Completion of vaccination, deworming, and implant procedures before weaning allows calves to be weaned without handling.
Early weaning of beef calves at 90–150 days of age may create more efficient use of feed resources by directly supplementing calves to maintain weight gain rather than supplementing cows to produce milk. Weaning times as early as 30–60 days can increase reproductive performance of cows and heifers. Cows and heifers cycle and rebreed earlier in the calving season, and pregnancy rates are higher in a limited breeding season after early weaning. Nutritional needs of the weaned calves must be met carefully to ensure acceptable health and performance. Weaning this early should only be done in an emergency situation to salvage the reproductive future of cows in extremely thin (BCS <4) condition at calving. The goal is to prevent this situation through strategies that improve BCS precalving (see Body Condition Score). Weaning at 150–170 days of age decreases lactational stress on cows when forage resources are limited and improves cow condition. Reproductive performance in the breeding season is not affected by weaning at this time. When forage resources are limited, weaning calves to decrease the nutritional requirements of the cows allows them to regain condition before winter with less or no supplementation. It is more efficient to wean the calves and feed them directly than to feed the cows more to increase milk production late in lactation.
Replacement heifer development programs generally commence at weaning as the heifers begin preparation for their initial breeding season. However, decisions relating to use of hormonal growth-promoting implant programs (see Growth Promotants and Production Enhancers) for replacements must be made beginning at the working of calves at 2–3 mo of age. Reimplanting heifers intended for breeding at weaning, or after 6 mo of age, is not recommended. Heifers that calve at 22–24 mo of age have increased lifetime production compared with heifers that calve first at 30 or 36 mo of age.
Selection of replacement heifer prospects begins at weaning, when heifers are typically 6–8 mo old, and is based on birth date, genetics, frame score, disposition, weaning weight and ratio, and dam production records. Selection of heifers born early in the calving season leads to replacement heifers that are older and heavier at the start of the breeding season. Heifers should be evaluated for structural soundness, and unacceptable conformation should disqualify a heifer as a replacement prospect. Age-adjusted frame scores can be used to estimate the mature size of prospects. These scores provide an objective method of selecting replacements to maintain a constant cow size suitable for the environment and feed resources.
Once potential replacement heifers are selected, a nutrition and vaccination program should be instituted in preparation for breeding. If heifers are to calve at 22–23 mo of age, they must be bred at 13–14 mo of age. For optimal fertility, heifers should weigh ~55−65% of their mature body weight by this time. The ration must be balanced to provide the required rate of gain to meet the target goal of 55–65% of mature body weight in the time available. Specific requirements vary with the weight and breed of the heifers and the amount of time available before breeding. (Also see Cattle.)
The vaccination program for replacement heifers should provide optimal protection from reproductive diseases and should include vaccination for infectious bovine rhinotracheitis (IBR) and bovine viral diarrhea (BVD). Depending on the local disease risk, vaccinations for Brucella, Leptospira, Trichomonas, and Campylobacter may also be indicated. Brucella vaccination is performed according to state or regional regulations. Modified live vaccines for IBR and BVD give the broadest immunity to strain differences and should be given twice to ensure a high level of immunity. Some evidence suggests that modified live BVD and IBR vaccines may transiently infect the ovary and cause decreased fertility. For this reason, vaccination should be done ≥1 mo before breeding. Vaccination of heifers with Trichomonas vaccine increases calving rate and decreases duration of infection in infected herds but does not prevent infection. A vaccine for trichomoniasis may be useful in infected herds or in herds that are at high risk of infection, but it may not be economic in low-risk herds.
Heifers should be well developed at the time of first breeding, and their management during gestation must ensure their continued growth. Pregnant heifers should be separated from the main cow herd at the time of pregnancy testing and maintained separately until reentry into the breeding herd after their first calving. Undernutrition during pregnancy in first-calf heifers can lead to an increased incidence of dystocia because of lack of weight and size, weakness at the time of parturition, insufficient colostrum, weak calves at birth, and a high incidence of prolonged postpartum anestrus, which leads to a high percentage of nonpregnant animals that will need to be culled. Thus, pregnant heifers should be fed and managed separately from cows and should be on a higher plane of nutrition than cows. Such management may slightly increase calf birth weight but will not increase dystocia scores if heifers calve in BCS 6–7. Heifers should be bred 2–3 wk before cows and be bred for a shorter period of time (~42 days) to ensure heifers with the highest fertility are retained in the herd. This also ensures that any increase in the postpartum anestrus period after their first, perhaps difficult, calving does not compromise their chances for cycling and rebreeding with the main cow herd.
General Health Management Considerations
The greatest risk for initial introduction of many infectious diseases into a herd is the addition of subclinically infected animals, although some risk is also attributable to wildlife carriers. Potential sources of infection may be seen with herd additions, or through intentional or inadvertent movements and contacts. Herds may be classified as “closed” or “open,” based on their potential for pathogen exposure. (Also see Biosecurity.) Closed herds restrict the introduction of animals and vehicles from livestock sources as well as contact with other herds and animals. Open herds have a higher risk of introducing pathogens through such practices as introduction of purchased replacements (especially from commingled sale groups), purchase of bulls, direct introduction of high-risk stocker calves (especially into high population densities), and mingling of animals of different backgrounds, through either cooperative breeding programs or poor herd biosecurity.
In general, all purchased or introduced animals should be separated from the home herd for a reasonable observation period (eg, 4 wk); these animals should undergo the same health procedures as the home herd. It is prudent to obtain animals from herds in which the herd health history is known and to have a record of vaccinations and treatments. Before purchasing animals, buyers should be sure that herds have tested negative for paratuberculosis and are free of persistently infected BVD, tuberculosis, and brucellosis. If the owner's herd is free of diseases such as bovine leukosis and anaplasmosis, purchasing only animals from herds negative for these diseases is vitally important. Pubertal bulls should be tested for trichomoniasis and vibriosis when indicated. For artificial insemination (AI) programs, semen should be used only if it was processed by an approved AI center with a comprehensive health program for minimizing the risk of transmission of venereal (and other) diseases through frozen semen.
Last full review/revision July 2011 by W. Mark Hilton, DVM, DABVP