Research »   Reproductive Failure

Reproductive Failure

Reproductive failure is extremely costly for producers, and goes undiagnosed in 25% of affected herds. Common known causes for reproductive failure are bull infertility, venereal diseases, such as trichomoniasis (trich) and vibriosis (vibrio), and poor cow nutrition. Reproductive failure is the most common reason associated with culling cows from the breeding herd.

The expense of an open cow to a producer is not only the lost value of a calf (approximately $800-900), but also the cost of maintaining the cow for a year without a calf being produced ($600-750).



Nutrition is probably the most important factor that influences cow fertility. Cows deficient in energy (indicated by body condition) or trace minerals preferentially partition these nutrients to maintenance rather than reproduction.

Body condition score

Adequate winter nutrition is necessary to maintain an optimal cow body condition score (>2.5 out of 5) in order to:

      • encourage calving ease
      • maintain high colostrum quality
      • sustain adequate milk production
      • ensure relatively prompt rebreeding

Copper deficiency

Blood samples indicate that up to 46% of cows in Western Canada may be copper deficient. Cows with blood copper levels below 0.4 ppm prior to breeding are at increased risk of not becoming pregnant, particularly young cows less than 4 years of age. This suggests a need for field research on the use and effectiveness of trace mineral supplementation programs to improve fertility of beef cows.

Venereal Diseases

The majority of beef herds in Canada continue to use bulls to breed their females, and are therefore susceptible to sexually transmitted diseases. The most commonly reported venereal diseases of cattle include trich and vibrio. Although both diseases occur infrequently, the results of infection can be quite devastating.


Trich is caused by a protozoan parasite called Tritrichomonas foetus (T. foetus).

Vibrio is caused by bacteria called Campylobacter fetus venerealis.


Both trich and vibrio are transmitted through physical contact. The sheath (prepuce) and penis of an infected bull and the reproductive tract of the cow serve as the primary site of infection for both diseases.

Bulls that become infected when they are greater than 3 years of age are considered infected for life.

When a cow is bred by an infected bull, the vibrio or trich organisms are passed from the penis to the vagina. These infected cows may then serve as a source of infection for other non-infected bulls within the herd. Cows that become pregnant and calve successfully are very unlikely to carry the infection.


No noticeable swelling or other clinical signs in the bull is caused by either disease. The semen of affected bulls will also appear normal on a breeding soundness examination.

Low pregnancy rates in bull bred beef herds are frequently caused by venereal diseases.


Herds infected with trich or vibrio will have:

      • Low pregnancy rates
      • Higher percentage of open cows
      • Extended breeding season, with cows that conceive much later than expected

Newly infected cows may still conceive, but their resulting pregnancy is commonly absorbed between 40 and 70 days after breeding. Cows that have aborted may start to cycle again, but experience temporary infertility for 1 to 5 months as they clear the infection. Once the infection is cleared, a cow may conceive again during the same breeding season.


Rule out other causes

Producers should test and cull infected bulls

herds that experience reproductive failure, producers should first review for breeding and nutritional management, including:

  • bull to female ratio
  • body condition of the cow herd
  • mineral program
  • consideration of heat stress

and ensure that all bulls have satisfactory breeding soundness examination.

Testing for Trich

Assuming the bulls are still available for disease testing, they should then have a scrape sample collected from their sheath. For trich, the scrape sample is flushed into a pouch with broth for growing the parasite. Traditionally these pouches were incubated and examined with a microscope on days 3, 5 and 7 after collection for the presence of the trich organism.

More recently, polymerase chain reaction (PCR) tests that identify a specific gene sequence from the organism have been developed. These PCR tests are able to identify a smaller number of trich organisms and are considered more specific to T. foetus. Occasionally bulls may have trich-like organisms found on culture as a result of manure contamination, but PCR tests are able to correctly identify them as false-positive cultures.

Herds with suspected or confirmed trichomonosis should test their bulls 3 times at weekly intervals with either culture or PCR before considering them negative. For routine screening of larger bull batteries with low risk of disease, using PCR on pooled samples made from up to 5 individual bulls has been found to identify a positive bull greater than 90% of the time (Kennedy et al., 2008). This is comparable to the detection rate of a single culture or PCR test on an individual bull.

Testing for Vibrio

Testing for vibrio usually involves the collection and culture of a scrape sample from the sheath of a bull. However, the bacteria causing vibrio are very temperature sensitive and commonly die on route to the diagnostic laboratory if transport of more than 24 hours is required. PCR tests have been developed and recently evaluated. PCR tests for vibrio are 85% accurate at identifying positive and negative bulls when sampled in the field. While not perfect, it is an improvement in what has been available to practicing veterinarians.

Other Tests

If the bulls are unavailable for testing, a diagnosis of either trich or vibrio can be made from aborted fetuses or even the vaginal mucous of carrier females. However, finding an aborted fetus with either disease is uncommon and the short duration of infection in females can make finding infections difficult. Perhaps focusing cultures on females with obvious reproductive tract infections (pyometra) would be more diagnostic.

Prevention and Containment

Infected animals should be culled. Identifying and replacing positive bulls with virgin bulls remains the cornerstone of controlling both venereal diseases. Cows that are open or which conceived late in the breeding season should also be removed from the herd. Only cows that have their calf at foot should be allowed to be a part of the breeding herd.

Vaccinate cows and bulls for vibrio before going to communal grazing pastures for breeding.

Vaccination for vibrio is available and is most protective to cows and bulls when given twice 3 to 4 weeks apart, and prior to breeding.

Initiating a timed artificial insemination program is great method to prevent disease, but will still require either heat detection or a bull for “clean up”.

For further information on this topic, please consult with your veterinarian.


BonDurant, R.H., Venereal Diseases of Cattle: Natural History, Diagnosis, and Role of Vaccines in their Control. Veterinary Clinics of North America, Food Animal Practice, 2005. 21 (2): 383-408.

Kennedy, J.A., et al., Pooled Polymerase chain reaction to detect Tritrichomonas fetus in beef bulls. Journal of Veterinary Diagnostic Investigation, 2008. 20: p. 97-99.

Van De Weyer, L., S. Hendrick, and C. Waldner. 2011. Associations between pre-breeding serum micronutrient concentrations and pregnancy outcome in beef cows. Journal of the American Veterinary Medical Association. 238: 1323-1332.


Learn More

To learn more on this topic, see the fact sheets posted on the right side of this page. External resources are listed below.

Effects of Nutrition on Beef Cow Reproduction
Alberta Agriculture and Rural Development

Moldy Feed and Reproductive Failure in Cows
Alberta Agriculture and Rural Development

Nutrition and Reproductive Efficiency



Feedback and questions on the content of this page are welcome. Please e-mail us at info [at] beefresearch [dot] ca.


Thanks to

      • Dr. Steve Hendrick, researcher and professor at the Western College of Veterinarian Medicine, University of Saskatchewan, and
      • Dr. John Campbell, researcher and professor at the Western College of Veterinarian Medicine, University of Saskatchewan

for contributing their time and expertise in writing this page.

This topic was last revised on February 29, 2016 at 09:02 AM.

Fact Sheets

Canadian Cattlemen's Association Verified Beef Production Canada Beef
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