Breeding Cow Management

Managing a breeding cow to produce a healthy, live calf each year is the foundation of a profitable cow-calf enterprise. There are many inter-related factors that can impact the reproductive success of a cow including nutrition, breeding season management, disease, bull management and environmental impacts.  

Key Points
Nutrition is the most important factor affecting cow fertility. Nutritional requirements of beef cows will change depending on stage of production – aim for a BCS of 3.0, and keep breeding females on a rising plane of nutrition from breeding to lactation.
Ensure cows in your breeding herd are healthy enough to breed, maintain a pregnancy, calve and raise a calf to weaning. Market animals of concern before breeding or do not re-breed. 
When retaining replacement females, select from cows that have good feet and legs, calve easily and have a good mothering ability. Keep replacements from low-maintenance cows who raise the best calves that will enhance the long-term goals of your farm. 
A controlled calving season improves the marketability of calves and the longevity of cows and maintains breeding momentum. Aim to have 85% of cows calving by the end of the second cycle and 95% by the end of the third cycle, as a benchmark. 
Aim to have open rates below 6% for cows and 8% for heifers, as a benchmark.   
Pregnancy checking is a useful tool to identify potential breeding issues and inform an open cow protocol. It is an important record to help identify areas of improvement and set breeding goals.
Maintaining a year-round mineral program is recommended to ensure that mineral requirements are met and pregnancy rates are not impacted.
Artificial insemination (AI) can be a useful, cost-effective tool for any cow-calf operation; however, it can be labour-intensive and require facilities and infrastructure. 
Natural bull breeding is a common, low-labour method of breeding cows. However, year-round bull management is critical for successful breeding. 
Biosecurity and a robust vaccine protocol developed in consultation with a veterinarian is the best way to keep disease out of the herd and maintain high pregnancy rates.  

Selecting the Breeding Herd

The breeding cows you select and keep in your herd should result in a calf every year (in the short term) while supporting the goals and objectives of your farm over the long term.  While every farm will have its own unique selection criteria, the overall goal is to strive for continued improvements in genetics and production potential of the calves destined for market, whether it is for commercial beef production or breeding stock. 

red cow and nursing calf in green grass

Effective breeding cows should:  

  • Be healthy and strong enough to breed, calve and support a calf to weaning 
  • Possess good mothering ability 
  • Have good foot, leg and udder conformation  
  • Have an adequate body condition score (BCS = 3) at the time of breeding and calving  
  • Calve easily and have a history of unassisted births and no history of prolapse or other calving-related medical issues  
  • Have a genetic foundation that contributes to the goals of your operation  

Breeding Season Management

The goal of a cow-calf operation should be for every cow and heifer to raise a calf to weaning every year. Planning, management, labour and effort are needed to achieve this simple, straightforward goal. Whether using artificial insemination (AI) or natural service, it is important to consider all of the different variables that affect a successful breeding season and the resulting calving season.  

Determining an ideal time for breeding and having a well-defined calving season, in addition to tightening up calving distribution, can help contribute to the overall success of an operation.

red beef bull and cow

See the BCRC’s Bull Management and Heifer Development topic pages for more information.  

Calving Distribution

Having a controlled calving season of 60 to 90 days in length can improve calf health and marketing management due to having a more uniform calf crop that is of a similar age. It can also allow a cow to effectively and predictably re-breed following calving. In addition, shorter calving seasons improve the longevity of the cow herd with studies showing heifers that calve in the first cycle remained in the herd for 5.1 years compared to 3.9 years for heifers calving after the first 21 days of the calving season.i  

Having a shorter calving season means having a defined breeding season where a bull is placed with a breeding cow herd and then removed after approximately three cycles. If a producer wants to shorten the calving season or change when the calving season occurs, it is important to transition slowly to avoid negatively impacting pregnancy rates.  

BCRC Value of Calving Distribution Calculator

To assess your herd’s current calving distribution and evaluate the impact of moving to a more condensed calving season, use the Value of Calving Distribution Tool

Selecting Your Breeding and Calving Seasons

When producers decide to breed cows will impact management and, ultimately, will determine when the calving season will occur (winter, spring, fall, summer). Considerations like labour availability, feed availability, infrastructure, weather and marketing goals will affect a producer’s calving season decision. Understanding the pros and cons of calving at different times of the year for a particular region and operation can help determine the best timing for the best possible pregnancy and weaning rates.  

For more information on refining the calving period or how to transition to an earlier or later calving season, check out the BCRC’s Calving Seasons topic page.  

Maintaining Reproductive Momentum

The importance of maintaining momentum throughout the breeding season is well established. Numerous studies show there are economic benefits to having at least 60% of cows and heifers become pregnant during the first 21-day cycle. A good benchmark to aim for is 85% of calves arriving by the end of the second cycle and 95% by the end of the third cycle. 

Changes to breeding season management can result in substantial changes to pregnancy rates, both positive and negative.  The average length of time from calving to fertile estrus is 50 to 80 days in most beef herds, but it takes closer to 70 to 100 days for 90% of mature cows to return to estrus after calving.ii  This time is longer in heifers, which require 80-100 days to resume cycling. Cows calving late one year due to a reproductive problem are significantly more likely to be open the next. 

Normal Reproductive Rates

Data from the Western Canadian Cow-Calf Surveillance Network (2014-2017)iii showed that 50% of herds had less than 6% of cows and 8% of heifers open or unbred at pregnancy testing. Producers should aim to have open rates at or below these benchmarks. Open rates greater than 13% for cows or 24% for heifers were reported less than 5% of the time and would be considered very unusual.

If producers are experiencing these levels of open rates, they should contact their veterinarian. Breeding heifers two weeks before cows and feeding heifers separately from cows may help to reduce some of the problems associated with getting heifers bred on schedule. Another strategy may be to breed heifers at the same time as the cow herd with a condensed breeding season for heifers to maintain a tight calving interval. 

While most herds periodically experience a few abortions, abortion rates greater than 3% for cows and 6% for heifers would also be considered cause for serious concern based on the surveillance network data. Most herds reported abortion rates of less than 1% per year. 

Pregnancy Checking

BCRC economics of pregnancy testing calculator

Keeping good records is important to track changes in pregnancy and abortion rates in your herd over time. Producers who have a veterinarian pregnancy test the herd each year are more likely to identify problems when it is still possible to determine a cause and potentially limit future losses. Pregnancy testing also allows producers to strategically manage the open cows in the herd.  

Assuming a spring calving schedule, generally producers have three options for managing open cows: 

  • Preg-check and cull non-pregnant cows in the fall. 
  • Preg-check in the fall and feed non-pregnant cows separately to market at a later date. 
  • Do not preg-check and overwinter all cows and cull opens in the spring after calving. 

If pregnancy rates drop, producers should not rule out issues such as appropriate bull-to-cow ratios for the bull age, pasture size and terrain type.  Other issues to consider include the potential for any reductions to the length of the time when cows were exposed to bulls or changes in the time the cows had to recover and start cycling again from calving to the start of the next breeding season. Drought, nutrition, the body condition scores of females and/or bulls, forage quality, water quality and parasites are additional factors that can also result in reduced conception rates. Read more about how to rebound from high open rates.  

Reproductive Record-Keeping

Record-keeping is essential to understand current reproductive rates, identify problems, track genetic progress and set targets to help guide future decisions. Records can help producers decide which cows to keep, which bulls to source, which potential replacement females to bring into their program and potential cows to market if their time on-farm has expired.  

Understanding the history of your current herd allows you to reliably cull unprofitable individuals or identify and market potential problem cows, such as cows with a history of assisted births or mismothering behaviour. Our Cow-Calf Record Keeping Courses are designed for beef producers working to strengthen their farm record-keeping and analysis skills for profitable decision-making.   

  • Records for Tracking Genetic Improvements  
  • Animal Health & Performance  
  • Forage & Grasslands Records  
Cow-Calf Record-Keeping Course on Tracking Genetic Improvements
cow-calf record-keeping course animal health & performance
Cow-Calf Record-Keeping Course for Forage & Grasslands

Artificial and Natural Breeding 

Although artificial insemination (AI) of cattle has been possible for 60 years, this technology has not been used widely in the Canadian beef industry.  Genetic evaluation of beef bulls has improved considerably over time, making herd bull selection more objective and reliable.  

There are specific benefits to AI and synchronized breeding. The ability to select for specific traits identified through DNA markers, the potential to use sexed semen and the ability to effectively use expected progeny differences (EPDs) can make AI a promising venture. Considering the costs of natural service and the infrastructure and management required to maintain herd bulls year-round, AI can be profitable, even in commercial herds.  

In addition to making refined breeding decisions and advancing the genetics of a herd more quickly, AI can facilitate a shorter breeding season which means more cows calving in the first cycle, more weight on calves at weaning and a more uniform calf crop.  

Some common downsides to adopting AI are limited time, labour and access to breeding facilities and infrastructure. During insemination, cattle need to be closely monitored and near handling facilities which may be a barrier for producers with multiple breeding pastures spread out over a large area.  

Having a highly skilled and experienced AI technician is also important to ensure a greater chance of a successful pregnancy, to prevent reproductive issues and to minimize breeding problems due to improper handling of semen. 

Natural breeding, on the other hand, is a low-maintenance, less labour-intensive option for breeding cows. It can take place on pastures anywhere, including far from home. Despite being comparable, natural breeding also provides greater pregnancy rates. Some downsides include the significant costs and infrastructure needed for year-round management of bulls. As well, natural mating bulls still need to be monitored for signs of sickness or injury, as those risks can compromise pregnancy rates.  

Pros and Cons of Natural Breeding and AI

Natural Breeding Pros and Cons
Pros Cons
Low labour-intensive breeding season  Management of bulls (vaccines, nutrition, bull soundness evaluations, injury prevention) year-round  
Does not require handling facilities and can be done in extensive pasture systems   Slower genetic progress – limited to on-farm bull power for the lifetime of available bulls 
Better pregnancy rates   Potential injuries to females and bulls associated with natural service 
Less risky than AI Flexibility over bull turn-out and removal dates  Typically longer calving season  
AI Pros and Cons
Pros Cons
Can select for high-value genetics and quickly advance genetic progress   Labour-intensive breeding season to synchronize and inseminate breeding females  
Does not require the purchase or management of bulls on-farm   Requires a trained and skilled AI technician to breed and handle semen  
Calf crop uniformity    Pregnancy rates are similar, but can be lower, than natural service 
More control over the timing of the calving season  Estrous synchronization drugs required 

If planning on using AI remember to:  

  • Minimize stress during handling.
  • Ensure cattle being inseminated are at an appropriate body condition score. 
  • Consult with your veterinarian. 

Bull Power

Whether you are planning on using AI or a natural breeding system, bull selection is critical as this defines 50% of the resulting calf crop’s genetics. Take time to select a bull that reflects your management goals whether they are maternal traits, growth, or carcass traits. Maintaining and reviewing records can help you determine areas that producers may wish to improve.   

Source a bull that fits within your budget and will help improve the productivity and profitability of your herd. The value of a bull depends on individual performance, markets, and management style.

Calving Ease & Interventions

Cows that have problems at calving are less likely to rebreed during the next calving season. Cows that required fetal manipulation or a Caesarean section are less likely to be pregnant the following year. Similarly, cows that abort or lose their calf at birth or within the first few hours of birth are more likely to be open after the subsequent breeding season. Thin or excessively over-conditioned cows are also more likely to have problems at calving. 

While assistance during calving is low in Canadian herds, assisted births occur on most operations at least once over the calving season. Assisting with a difficult calving situation can be stressful, however timely intervention can help provide a good outcome for both the cow and the calf, and ensure that cow raises a calf that season. Find a complete list of emergency support resources for distressed newborn calves.  

While occasionally necessary, assisting at birth can be costly. Heifers and cows that require assistance during calving have a higher cost of production and garner less profit than females who calve without intervention. Research suggests this can be around $5.29/head for pulled calves and $42.32/head for C-sections in labour costs alone without considering production, facility and material expenses.  

Nutrition and Body Condition Scoring (BCS) 

impact of body condition score on cow productivity and profitability

Nutrition is the most important factor affecting cow fertility. Cows consuming a diet that is deficient in energy and that have low body condition score (BCS) or lose condition after calving are much less likely to be pregnant in the fall than cows in better condition. Maintaining an ideal BCS of 3 will help ensure a cow maximizes her productivity by producing a calf every 365 days. 

Adequate winter nutrition is necessary to maintain a cow in an optimal BCS in order to: 

  • minimize time to rebreeding and enhance pregnancy rates 
  • decrease the risk of abortion and calf death at or near birth 
  • encourage calving ease (very thin cows have the highest risk of difficult calving) 
  • sustain adequate milk production 

Calculate the numbers for your own operation using the BCRC’s Impact of BCS on Cow Productivity and Profitability tool

Nutritional requirements of beef cows will change depending on stage of production. These stages include (based on the ideal length of time for each phase):  

  • Calving, postpartum, early lactation (day 0 to day 82) 
  • Conception, early gestation, late lactation (day 83 to day 199) 
  • Mid-gestation (day 200 to day 274) 
  • Late gestation, pre-partum (day 275 to day 365)

A common rule of thumb is 55-60-65% for total digestible nutrients (TDN) and 7-9-11% for crude protein (CP) for mid-gestation, late-gestation and lactation. 

Calving, Postpartum, Early Lactation

This phase begins at calving. This is the period of greatest nutritional demand for the cow. She must lactate, repair her reproductive tract, resume heat cycles, breed, and if she is a young cow, she must also continue growth and development. Her voluntary feed intake is highest at this point and she requires a high energy and protein diet of at least 62% TDN and 11% CP. If she is not fed to meet nutritional needs, she will lose weight and may not rebreed. 

Conception, early, gestation, late lactation

This phase begins with conception. The cow is now supporting herself, her calf (through lactation) and her fetus. Nutritional demands are still high as she reaches peak lactation but are lowered by 8-13% compared to the first phase. Cows that produce more milk will have higher nutrient requirements. The fetus is small, and its growth is slow, but cows and heifers often lose weight during this time. 


Occurs when the cow is in mid-gestation. Immediately after calves are weaned, nutritional needs are at their lowest due to the end of lactation. Energy and protein requirements drop by up to 35% when compared to the peak demand. Fetal growth remains slow, and voluntary feed intake is the lowest during this period. This is the best time to put weight back on cows to help them gain condition.  

Late-gestation, pre-partum

This is the final phase prior to calving, and cows must be in good body condition to give birth to a healthy calf, produce milk and re-breed quickly. Energy and protein needs increase by 20% compared to mid-gestation. During this period, the fetus can gain up to 60 pounds and the placenta is growing as well. Nearly 75% of fetal growth occurs during this phase11. Cows need to gain 0.5 kg (1 lb) to 0.68 kg (1.5 lbs) per day, while weight gain for heifers should target twice that amount. The cow has reduced rumen capacity due to the growth of the calf, so a reduction in feed intake usually occurs in the latter portion of this phase. 

Antinutritional Factors Influencing Fertility

Nutrient deficiencies

Maintaining a year-round mineral program is recommended to ensure that mineral requirements are met and pregnancy rates are not impacted. Trace mineral supplementation should take place according to product recommendations and in consultation with a nutritionist or veterinarian. All trace minerals, including copper, have the potential to be toxic at very high levels of intake. Annual testing of water, feed, and ideally pasture is recommended, as mineral levels can vary from year to year even in the same water source, pasture, or hayfield.  Surface water sources (such as dugouts) are particularly vulnerable to changes in sulfate levels (which can tie up copper) and total dissolved solids (decrease mineral intake). 

Copper Deficiency

Copper is a critical mineral when it comes to reproduction. Copper deficiencies can result in:

  • increased number of open cows 
  • poor growth 
  • changes in hair colour 

Blood samples collected in 2014 indicate that up to 43% of cows in Western Canada may be copper deficient (< 0.5 ppm). More than 85% of herds have at least one deficient animal. Cows with blood copper levels below 0.4 ppm prior to breeding are at increased risk of not becoming pregnant, particularly young cows. 

Mineral supplementation is one way producers can help combat copper deficiencies. While most producers will provide free choice trace mineral supplements, not all cows consume enough to maintain adequate levels. Further field research is needed to identify cost-effect trace mineral supplementation programs to improve fertility of beef cows. 


Exposure to various types of toxins can also impact reproductive performance. One of the most common examples of toxins occurring in Western Canada is ergot, which can increase during growing seasons that have abundant precipitation. Ergot affects cattle in several ways including an increased risk of abortions.

Fusarium mycotoxins have also been identified more frequently in cereal grains in recent years.  The wide variety of mycotoxins produced by Fusarium, including zearalenone and vomitoxin, have been linked to infertility and abortion. Therefore, it is recommended to NEVER feed moldy feed to pregnant or lactating cows and heifers. Detection of mycotoxins can be challenging, however, ensuring your annual feed test encompasses a test for mycotoxins can stop a wreck before it happens.  

Disease Prevention for Herd Health and Reproductive Assurance


Managing disease and biosecurity hazards is an important part of breeding cow management. The first line of defense against disease outbreak is prevention. Understanding your on-farm biosecurity hazards like shared fence lines, buying replacement heifers or bulls, borrowing trailers or hosting visitors can prevent the unintended introduction of disease to your cow herd.  

Having well-defined cleaning and biosecurity protocols like quarantining new animals to verify their health and ensure they have been properly processed before being introduced to the main herd is the best way to keep your cow herd protected.   

Learn about biosecurity planning and more on the BCRC’s Biosecurity topic page.   

Think you have a closed herd? Think again.

Click for an interactive graphic reviewing common ways a herd becomes open, allowing disease to enter your herd.

do you think you have a closed herd?

Venereal (Sexually Transmitted) Disease

Most beef herds in Canada continue to use bulls to breed their females, and therefore, are susceptible to venereal (sexually transmitted) diseases. The most common venereal diseases of cattle include trichomoniasis (trich), vibrio and leptospirosis (lepto). Although these diseases occur infrequently, the results of infection can be devastating causing abortions, infertility and in some cases, death. 

white cow and black bull on grass

Trich and vibrio are transmitted through natural breeding when a bull physically breeds a cow. Once a cow is infected, they act as a source of infection for other non-infected bulls within the herd which then spread the disease(s) to other cows. Cows that are in that breeding pasture but become pregnant and calve successfully are unlikely to carry the infection. 

Symptoms and Consequences

Low pregnancy rates in naturally bred beef herds can be caused by venereal diseases.

None of these diseases cause clinical signs in the bull and the semen of affected bulls will also appear normal on a bull breeding soundness examination (BBSE). Some strains of leptospirosis will result in sick animals with a variety of clinical signs within the herd.   

Herds infected with trich or vibrio will typically have:  

  • Low or very low pregnancy rates due to early embryonic death   
  • High numbers of open cows at calving 
  • Early abortions   
  • Extended breeding season, with cows that conceive much later than expected (i.e., cows can lose their first pregnancy and rebreed later in the breeding season – particularly in herds that do not have a defined breeding season)  

Newly infected cows may still conceive, but their resulting pregnancy is commonly lost between 40 and 70 days after breeding. Cows that have aborted will typically start to cycle again but experience temporary infertility for one to five months as they clear the infection.  

Herds infected with lepto will typically have:   

  • Low pregnancy rates   
  • High number of open cows 
  • Infertility   
  • Weak calves   
  • Reduced body condition   
  • Abortions at any stage of gestation   
  • High fever   
  • Kidney failure   
  • In rare cases, death

Prevention and Containment

be wise and immunize cattle

Cows and bulls should be vaccinated for vibrio before going to communal grazing pastures for breeding. Preventative testing can be done at the same time as the BBSE by a veterinarian prior to bull turn-out. Testing bulls for venereal disease is required by most community or multi-patron pastures to reduce the risk of disease transmission. These tests can help avoid an outbreak before it happens.  


Infectious diseases, including venereal diseases, can present a great risk to producers who are rapidly expanding their herds by bringing in cattle from a variety of different sources or in situations where cows are co-mingled in community pasture settings. 

Bovine Viral Diarrhea Virus (BVD) and Infectious Bovine Rhinotracheitis Virus (IBR)

BVD infection can lead to poor conception rates and both BVD and IBR can cause abortions in cattle. Blood tests show exposure to these diseases is common in unvaccinated herds.

There is good evidence from several experimental trials that vaccines for these diseases are effective. Vaccinating for BVD can result in an average reported decrease of 85% in fetal infection and 45% reduction in abortions. On average, studies reported a 5% increase in pregnancy rates in vaccinated herds.iv  The IBR vaccine has been reported to reduce the risk of abortion by 60% on average.v

Field studies in Western Canada have shown a significant improvement in pregnancy rates and decrease in abortion rates for vaccinated cows when compared to unvaccinated cows on community, vii 

The BCRC’s BVD Vaccination Cost-Benefit Calculator can help a beef producer see the potential savings from vaccinating cattle for BVD.

bovine viral diarrhea vaccination cost-benefit calculator

BVD and IBR was the most common type of vaccination administered to mature cows and bulls as reported in a recent survey that was part of the Western Canadian Cow-Calf Surveillance Network. While most producers are vaccinating their cows, many producers forget to vaccinate their herd bulls. Bull vaccination presents an important opportunity to decrease the risk of reproductive failure. For example, the testicular tissue of bulls can potentially remain infected with BVD for prolonged periods and provide a source of the virus to susceptible cows and heifers.viii In herds where BVD is suspected, testing, and culling of persistently infected carrier animals can be considered as an additional management tool.  

Effective biosecurity and vaccination programs reduce the risk of infection in your breeding herd. Speak to your veterinarians to understand what vaccinations are available and recommended for your region and management. 


External and internal parasites are known to impact production. Consult with your veterinarian for a management plan to reduce or prevent any parasitic load.

Neosporosis is a parasitic disease that could impact an operation’s reproductive success. Neospora caninum is a protozoal parasite of canids such as coyotes and dogs that can be passed to a number of species, including cattle. It is a very common cause of abortions in dairy herds but has also been responsible for significant losses in some beef herds.  Blood tests have shown that the level of infection has stayed relatively stable over the past 20 years. On average, slightly more than one in every 20 cows has been exposed to the parasite at some time. The infection can be transmitted from the cow to her unborn calf, but not all exposed cows will abort. There is no effective vaccine or treatment for neosporosis. Careful dead stock management might help to minimize contact with coyotes in some areas. 


Managing for an effective and efficient breeding cow herd will have short-term benefits and is also critical to the long-term success, profitability and productivity of a cow-calf operation. Understanding the variables that affect reproductive success – or failure – can help producers pinpoint their strengths and weaknesses and work toward continued improvement.  


i Mousel, E.M., Cushman, R.A., Perry, G.A, and Kill, L.K.2014. Effect of Heifer Valving Date on Longevity and Lifetime Productivity. Driftless Region Beef Conference [January 30-31, 2014], Dubuque, Iowa.  

ii Larson, R.L., and White, B.J. 2016. Reproductive Systems for North American Beef Cattle Herds. Vet Clin Food Anim 32: 249–266 

iii Western Canadian Cow-Calf Surveillance Network (2014-2017)

iv Newcomer, B.W., Chamorro, M.F., Walz, P.H. 2017. Vaccination of cattle against bovine viral diarrhea virus. Vet Micro.Volume 206:78-83. 

v Newcomer BW, Walz PH, Givens MD, Wilson AE. (2015) Efficacy of bovine viral diarrhea virus vaccination to prevent reproductive disease: a meta-analysis. Therio Volume 83(3):360-365. 

vi Waldner CL, Garcia Guerra A. (2013) Cow attributes, herd management, and reproductive history events associated with the risk of nonpregnancy in cow-calf herds in Western Canada. Therio Volume 79:1083-94 

vii Waldner C. (2014) Cow attributes, herd management, and reproductive history events associated with abortion in cow-calf herds from Western Canada. Therio Volume 81(6), 840-848. 

viii Voges H, Horner GW, Rowe S, Wellenberg GJ. (1998) Persistent bovine pestivirus infection localized in the testes of an immune-competent non-viraemic bull.  Vet Microbiol Volume 61: 165-175. 


Feedback and questions on the content of this page are welcome. Please e-mail us at

Expert Review

This content was last reviewed June 2024.

This topic was last revised on June 20, 2024 at 5:11 pm.