Are There Any Buns in the Oven? Methods of Pregnancy Testing in Small Ruminants
As we head towards the end of the fall breeding season for most small ruminant producers, it's time to see if all that hard work from our rams and bucks paid off and we have some "buns" baking in the oven for spring. There are several methods that can be used to confirm pregnancy, and with some skill, most can be performed on-farm or with the assistance of a veterinarian. Confirming pregnancy as early as possible can have a significant effect on the profitability and efficiency of a farming operation. The longer a ewe or doe stays open, the more money is needed to put into feeding and caring for them without a guarantee of a return on that profit until they reproduce.
The most reliable method traditionally used in the industry is ultrasonography (USG), also commonly referred to as ultrasound imaging. This method utilizes a machine and a transponder to emit sound waves that are either transmitted through or reflected off various types of tissue and bone. When an object bounces back the sound waves, it creates an echo, which can then be interpreted by the machine to create real-time images and video. Ultrasound can be performed either internally or externally. Transrectal ultrasounds are a more time-consuming and invasive method, but can detect the presence of a fetus, or embryonic fluid as early as 20 days post breeding if done by a skilled technologist. Transabdominal ultrasound is a less invasive, rapid technique that can detect the presence or absence of amniotic fluid, or a fetus as early as 30 days post breeding if done by an experienced technologist. The accuracy of this technique is highest around day 45 post-breeding and can be used to determine the number of fetuses present up to 85 days post-breeding. The drawback of using ultrasonography for pregnancy detection is that it relies on the accuracy and skill of the technician performing the test. It can also be cost-prohibitive to small flock or herd owners; however, there are more on-farm units on the market now than ever before.
A newer form of on-farm pregnancy testing is testing the blood serum or plasma of ewes or does for Pregnancy-specific protein B (PSPB). This pregnancy-associated glycoprotein (PAG) is released by the placenta during pregnancy and circulates through the bloodstream. Several companies have developed goat/sheep side test kits, enabling producers to obtain accurate results in approximately 30 minutes by taking a blood sample for the test kit. A recent study also indicated that the bovine visual ELISA test for detecting PAGs can be used successfully to determine pregnancy in goats (Doğan and Köse, 2022). These tests are accurate when taken between 25 to 30 days post-breeding. There is also research being conducted that suggests a correlation between the level of PSPB and the number of fetuses carried by the dam; however, further research is needed to establish parameters for comparison and testing (Chen et al., 2025).
Another method of pregnancy detection is by testing the levels of progesterone (P4) in either blood serum or milk. The Corpus Luteum (CL) releases elevated levels of progesterone to prepare the uterus for the implantation of the embryo, and it maintains this elevated level of progesterone throughout pregnancy. If no embryo is implanted in the uterus, then the hormone Prostaglandin (PG F2α) is released to break down the CL, thereby reducing the levels of progesterone. It's important to note that this test must be done 60 to 80 days post kidding or lambing and after one cycle (19 to 24 days on average) after breeding due to the time it takes for the dam’s progesterone levels to return to normal after a pregnancy and then to come back up for the new pregnancy. If the test is done too early after a pregnancy or if it's a pseudopregnancy, then the results will be inaccurate. This option can be particularly beneficial for dairy goat or dairy sheep producers who already have their milk tested, as it maximizes the use of the milk samples already being submitted. This test cannot predict the number of fetuses that the dam may be carrying.
Less sensitive, but another way to test for pregnancy, is a urine test to check for elevated levels of estrone sulfate. Estrone sulfate is a type of estrogen that is released by the fetal-placental unit during pregnancy. Although levels of estrone sulfate can be detected in urine during early pregnancy, for the best accuracy, it's recommended to wait until 50 to 60 days post-breeding to take a sample. Although cost-effective, this method can also be a cause of frustration for producers to be able to collect a successful urine sample from ewes and does, and its timeliness could be a limiting factor for some producers.
Not only can we use pregnancy confirmation as a determining factor in culling unproductive females (or males, depending on the situation), but we can also use it to make more informed management decisions regarding nutrition and care of the dam as she progresses through her pregnancy. Dams that carry multiple fetuses are at a higher risk for metabolic disease, such as pregnancy toxemia. This is due to a significant increase in energy requirements during late pregnancy, which can be limited by reduced consumption as the abdomen has less space for both increased fetal growth and nutritional demands. Knowing this information ahead of time allows producers to make ration changes earlier on to alleviate or eliminate the number of cases of pregnancy toxemia in the flock or herd.
Technological advancements and increased research have made pregnancy confirmation in our small ruminants much more accessible and affordable than in the past. Choosing an option above should be based on your operations' needs and goals. Those using artificial insemination, flushing, or are breeding on an accelerated program will require quick accurate results for success in their reproductive programs.
Resources:
Stewart, Jamie Lynn. "Pregnancy Determination in Goats - Management and Nutrition." Veterinary Manual, Sept. 2024.
Chen, Y. T., et al. "Milk Pregnancy-Associated Glycoprotein Concentration as an Early Detection Biomarker of Multiparous Pregnancies in Alpine Goats." Small Ruminant Research, vol. 249, 2025, pp. 107519.
Akkaya Doğan, Aslı, and Ayşe M. Köse. "Evaluation of Bovine Visual ELISA Test for Detection of Pregnancy-Associated Glycoproteins in Early Pregnancy Diagnosis in Goats." Small Ruminant Research, vol. 212, 2022, pp. 106722.
Article first published in the Lancaster Farming NewspaperÂ
