Diagnostic Testing for Trichomoniasis in Cattle By Behind The Bench Staff www.thermofisher.com/blog/behindthebench/diagnostic-testing-bovine-trichomoniasis-cattle/ Test for Trich as Part of Herd Management Biosecurity Avoid Devastating Economic Losses
Performing diagnostic testing for bovine trichomoniasis, commonly referred to as Trich, 60 days prior to the breeding season and at the end of the breeding season should be a critical component of a producer’s plan for herd management biosecurity. While Trich may not be a day-to-day concern, an outbreak will devastate your cow–calf operation. What is Trichomoniasis? Bovine Disease Caused by T. foetus
Bovine trichomoniasis is caused by Tritrichomonas foetus (T. foetus). It’s a sexually transmitted protozoan parasite that infects bulls. Bulls are asymptomatic carriers of the disease but are responsible for trichomoniasis transmission. Older bulls are more at risk of having the disease than younger bulls. Unfortunately, bulls that test positive must be removed from the herd and culled since there is no treatment for the disease.Tritrichomonas foetus (T. foetus) parasite as seen through a microscope Infection and Reinfection Infection of the cow is caused by sexual contact with an infected bull. In the first stage of infection, cows do not have rapid conception failure. Most cows will naturally clear the infection within three months after breeding. However, immunity doesn’t last long and reinfection can occur, which would continue the infection cycle if not identified. Infection Rates Suggest Strain Differences
When cows are bred naturally by an infected bull, 30% to 90% become infected, which suggests that strain differences exist.1 In 2016, a novel South African genotype of T. foetus in cattle was discovered that is distinct www.progressiverancher.com
from other T. foetus genotypes in Europe, South and North America, and Australia.2 Global Variations in Prevalence of T. foetus
Prevalence of T. foetus is not the same in all regions of the world. Where artificial insemination (AI) is primarily used for breeding, the disease is limited. T. foetus has been considered endemic in the US since the 1980s, but some states show a higher incidence—for example, in Midwestern and western states like Kansas, Oklahoma, Texas, and California. Many other parts of the world experience a similar epidemiological situation. Countries like Brazil and Argentina also experience a higher incidence due to natural service being the primary means of reproduction.3 What Are the Signs of a T. foetus-Infected Herd? Increased Number of Short-Bred or Open Heifers
The first sign of a T. foetus issue that a producer will see is an increased number of short-bred or open heifers or cows. After conception, the pregnancy of an infected cow can progress up to 120 days, but abortion may occur at about 70–90 days. At that time, the embryo dies and is either reabsorbed or expelled.3 Repeated Heat and Breeding
Due to the embryonic death, cows will come back into heat and repeat breeding occurs. Often, producers or veterinarians identify a cow in heat that should be pregnant. If T. foetus is not identified during the breeding season, then producers can expect a reduced number of cows to calve during the regular calving season. T. foetus -Infected Herd Will See Significant Losses
Unfortunately, by the time a producer realizes they have a T. foetus-infected
herd, significant economic losses cannot be avoided. Losses will include culling bulls that are infected and, more important economically, abortion losses and cows that are unable to get pregnant, resulting in fewer calves born and marketed in a season. What Biosecurity Measures Can Reduce the Introduction and Incidence of T. foetus in Your Herd? • If purchasing a new bull, a negative trichomoniasis real-time PCR test should be required; if purchasing replacement females, ensure those cows or heifers come from a negative herd or require a negative PCR test. Alternatively, replacement cows should be isolated from the existing herd during their first breeding season. • Implement a defined breeding season, as it’s much harder to detect foetus in a continuous breeding program. • Good fences make for good neighbors—this old adage applies to foetus–infected herds. It’s best to maintain a solid perimeter fence to separate cows and bulls of unknown status, including cattle on your farm and neighboring herds.
• Keeping younger bulls can be sensible, as older bulls are more at risk of having the disease. • Keep records of bulls and their breeding group; this will make identifying infected bulls easier, so you can isolate and test quickly. • Monitor pregnancy rates closely, as a low number is a key indicator that foetus has entered the herd. • Quarantine bulls of unknown status until they can be tested.
• If infection is found, consider using AI short-term to help break the cycle; most AI companies regularly test semen for pathogens, including foetus. • Don’t share or lease bulls with neighboring operations.
• Annual foetus testing is recommended for all breeding herds. Since every bull goes through a breeding soundness exam once a year before they’re put into the pasture with cows and heifers, producers can use this time to collect a Trich sample to avoid running the bull through the chute twice.
The Progressive Rancher
Diagnostic Testing for Trichomoniasis Diagnostic testing for trichomoniasis is only available for bulls. All nonvirgin bulls should be tested on-farm prior to breeding season or comingling in the herd. Some states and countries require testing prior to import/export or prior to bull sales across state lines. The Presence of T. foetus Can Be Confirmed by a Real-Time PCR Assay Real-Time PCR Provides Faster Results Than Culture
Real-time PCR is the ideal test to use for Trich because it provides faster results than culture (usually one day) and a higher level of confidence in the results. To reduce costs, it’s possible to pool tests, which involves testing a group of nonvirgin bulls using one diagnostic reaction to meet the state or country requirement. In herds where Trich has been identified, individual tests are required. Identify Infections Quickly, Reduce Risk of Infections and Economic Losses
Using real-time PCR testing as part of a herd management biosecurity plan, T. foetus infections can be identified more quickly, allowing pregnancy rates to increase and limiting the economic consequences of this disease. Other Resources & Information
Tritrichomonas foetus Can Be Devastating to Calving Rates: www.thecattlesite.com/ news/52495/tritrichomonas-foetus-can-bedevastating-to-calving-rates/ Trichomoniasis Management Helps Increase Calving Rates: www.thecattlesite.com/ articles/4367/trichomoniasis-managementhelps-increase-calving-rates/ Trich PCR Testing for Cattle is Booming Business in Idaho, USA: www.thecattlesite. com/news/51718/trich-pcr-testing-forcattle-is-booming-business-in-idaho-usa/ REFERENCES: 1 Casteriano, A., Molini, U., Kandjumbwa,K., Khaiseb, S., Frey, C., & Slapeta, J. (2016) Novel genotype of Tritrichomonas foetus from cattle in Southern Africa. Parasitology, 143(14), 1954-1959. 2 Trichomoniasis In Cattle – Reproductive System (2022) MSD Veterinary Manual, https://www.merckvetmanual. com/reproductive-system/trichomoniasis/trichomoniasis-incattle 3 Dąbrowska, Joanna et al. (2019) Tritrichomonas Foetus As A Causative Agent Of Tritrichomonosis In Different Animal Hosts. J Vet Res, vol 63, no. 4, pp. 533-541. Walter De Gruyter Gmbh, doi:10.2478/jvetres-2019-0072.
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