|Is she or isn't she?|
In the North Dakota study, pregnancy was detected as early as 20 days in one ewe; however, 72 percent of the ewes were falsely determined to be open when the test was conducted before 25 days of pregnancy. Testing between 25 and 30 days accurately determined pregnancy in 83 percent of pregnancies. Testing after 30 days of pregnancy accurately identified 98 percent of pregnant ewes.
Breed and age of pregnancy were strongly correlated with PSPB concentrations. Concentrations of PSPB were not correlated with litter size in the Katahdin and Hampshire breeds. Thus, the test could not be used to determine pregnancy rates in ewes of these breeds.
Concentrations of PSPB were strongly correlated with litter size in the Columbia and Dorset breeds. Thus, PSPB concentrations could be used to sort Columbia and Dorset ewes into pregnancy groups. However, the exact date of breeding would need to be known.
The BioPRYN (PRYN stands for "Pregnant Ruminant Yes No) test is commercially available from BioTracking, LLC. The test costs approximately $6.50, plus the cost of the sample tube and needle
The alternative to blood testing for pregnancy is ultrasound scanning, which requires expensive equipment and a highly trained technician. In some states, only licensed veterinarians may provide the service.
Source: Efficacy of pregnancy specific protein B assay to predict pregnancy and pregnancy rate in sheep, 2013 Sheep Research Report. North Dakota State University.