Pregnancy diagnosis in sows: Direct ELISA for estrone in feces and its prospects for an on-farm test, in comparison to ultrasonography

The usefulness of fecal estrone (E-1) measurement as a tool for pregnancy d iagnosis was investigated. Concentrations of E-1 were measured in feces fro m pregnant and nonpregnant sows by a direct ELISA without extraction. Highl y significant differences in E-1 concentrations were found in feces from no npregnant and pregnant sows (P = 0.016 to < 0.001). Pregnancy diagnosis on Days 26 to 32 after insemination, based both on fecal E-1 concentrations as measured by ELISA and ultrasonography using a 5.0 MHz linear-array transdu cer, was performed in a group of 496 gilts and sows. The fecal E-1 test had a sensitivity (correct diagnosis of pregnancy) of 96.5% and a specificity (correct diagnosis of nonpregnancy) of 93.6%, using 3.65 ng E-1/g feces as a cut-off value. For ultrasonographic pregnancy diagnosis the test sensitiv ity and specificity were 99.3 and 92.5%, respectively. Although an increase of fecal E-1 concentrations was noticed for increasing litter sizes, the r esults indicated that these concentrations could not be used to predict lit ter size. It is concluded that the distribution of fecal E-1 concentrations in both nonpregnant and pregnant sows offers a suitable basis for the deve lopment of a simple, sow-side pregnancy test. (C) 1999 by Elsevier Science Inc.