PREGNANCY DETERMINATION IN UNCAPTURED FERAL HORSES BY MEANS OF FECAL STEROID CONJUGATES

This study was carried out to develop an accurate, rapid and inexpensive method for diagnosing pregnancy in uncaptured feral horses by analysis of fecal steroid metabolites and to compare the accuracy of this method with diagnosis by urinary estrone conjugates (E1C). Paired urine and fecal samples were collected from 40 sexually mature feral mares during August and October. Urine samples were extracted directly from the soil and analyzed by enzymeimmunoassay (ElA) for E1C. Water extracts of fecal samples were assayed by ElA for E1C and nonspecific progesterone metabolites (iPdG). Urinary E1C, fecal E1C and fecal iPdG concentrations for seven mares which produced foals were 3.9 +/- 1.3 (SEM) mu-g/mg creatinine, 4.2 +/- 0.8 ng/g feces and 1.411 +/- 569.6 ng/g feces, respectively. Urinary E1C and fecal E1C and iPdG concentrations for the 33 mares which did not produce foals were 0.1 +/- 0.0 mu-g/mg creatinine and 0.5 +/- 0.1 and 32.8 +/- 4.5 ng/g feces, respectively. These differed (P < 0.01) from values in mares which produced foals.