Pregnancy diagnosis is a valuable tool to identify open (non-pregnant) cattle. Non-pregnant cattle need to be identified as soon as possible after the breeding season so that management decisions can be made. Three procedures can be used to diagnose pregnancy.
Rectal palpation is a simple procedure that requires little time or equipment to determine pregnancy. Most large animal veterinarians can perform this procedure. Rectal palpation can be performed accurately within six to eight weeks from the time of breeding.1 This is the most widely used form of pregnancy determination of the three. However, palpation cannot tell you if the embryo is viable. As embryo development progresses, fetal weight and length increase, and additional indicators of pregnancy status are possible, including sex and health of the embryo (table 1).
Table 1. Indicators of pregnancy status as embryo development progresses.
|Days of Gestation||Fetal Weight||Fetal Length||Fetal/Uterine Characteristics|
|30-35||1/100 oz.||2/5″||One horn slightly enlarged. Uterus in position of non-pregnant uterus. Embryonic vesicle size of quarter.|
|50-60||.25 oz.–.5 oz.||2″–2.5″||Uterine horn oblong, soft, and size of banana; fluid filled and pulled slightly over pelvic rim. Fetus is size of mouse.|
|100-120||.75 lb.–1.75 lb.||10″–12″||Both horns fluid filled, 4”–5” diameter and pulled over pelvic rim. Cotyledons become palpable (quarter size). Fetus is size of large rat or small cat.|
|180||10 lb.–16 lb.||20″–24″||Horns out of fetus reach over pelvic rim. Cotyledons become enlarged (half dollar). Fetus is size of small dog.|
|210-240||20 lb.–60 lb.||24″–36″||Fetus is large enough to be felt just over the pelvic rim.|
The second method of pregnancy diagnosis is transrectal ultrasonography with an ultrasound machine. Ultrasound imaging use sound waves to measure the density of tissues, making images of organs and structures inside the body.1 When utilizing ultrasonography, pregnancy can be determined as early as twenty-eight days. Additionally, a skilled technician can detect a heartbeat and number of fetuses after twenty-eight days and can determine the sex of the calf after sixty days.
Both rectal palpation and ultrasonography are reliable and relatively quick methods of pregnancy determination. Talk with your local veterinarian to decide which method is better suited to your operation.
The third method of diagnosis utilizes a blood sample. A blood sample is collected and shipped to a private lab or company, which then uses an assay to determine pregnancy status. The assay measures a protein produced by the placenta. Accurate pregnancy results can be achieved as soon as twenty-eight days after breeding as long as the cow is at least sixty days past her last calving date (which most cows are). The assays are accurate at determining pregnancy status; however, the test does not give days old, sex, or health of the embryo or fetus. It is a cost-effective method of giving an accurate diagnosis of whether cattle are pregnant or open. Blood collection can be conducted by the producer or farm staff and mailed to a participating lab for pregnancy determination.
Early detection of pregnancy is a benefit to producers, but it is important to remember most early embryonic mortality (pregnancy loss) occurs prior to day 60.2 Approximately 5% of cattle found pregnant on day 30 after breeding will lose the pregnancy by day 60. However, after day 60, pregnancy loss decreases significantly.
Pregnancy can be diagnosed using these three methods. Each method has benefits and costs. This information is meant to guide your discussion with your local veterinarian or Extension Livestock and Forage Agent. Call your County Extension office for the name and contact information for your local Extension Agent.
- Taverne MAM, Szenci O, Szétag J, Piros A. Pregnancy diagnosis in cows with linear‐array real‐time ultrasound scanning: A preliminary note. Veterinary Quarterly. 1985; 7(4): 264-270. [accessed 2019 Aug]. doi:10.1080/01652176.1985.9693998.
- Santos JEP, Thatcher WW, Chebel RC, Cerri RLA, Galvao KN. The effect of embryonic death rates in cattle on the efficacy of estrus synchronization programs. Animal Reproductive Science. 2004 Jul; 82-83: 513-535. [accessed 2019 Aug]. doi:10.1016/j.anireprosci.2004.04.015.