Pregnancy and ovulation detection in bison (Bison bison) assessed by means of urinary and fecal steroids.

Sexually mature bison (Bison bison) cows were tested for both pregnancy and ovulation by means of urinary steroid metabolites and fecal steroids. The accuracy of pregnancy diagnosis was determined among 18 bison cows, in approximately the third month of gestation, by means of urinary pregnanediol-3 delta-glucuronide (PdG), urinary estrone conjugates (E1C), and fecal total estrogens (TE). Urinary PdG was 100% accurate, urinary E1C was 89% accurate, and fecal TE was 100% accurate in predicting pregnancy. Fecal progesterone (P4) and TE, as well as urinary E1C and PdG concentrations all increased from conception (August) through January, but significant differences were not apparent until November. During the rutting season ovulation was detected by increases in either urinary PdG or fecal P4 concentrations. Both pregnancy and ovulation were detected in uncaptured bison with reasonable accuracy by means of urinary and fecal steroids or their metabolites.

Oestrous cycle of the North American bison (Bison bison) characterized by urinary pregnanediol-3-glucuronide.

An enzyme immunoassay for urinary pregnanediol-3 alpha-glucuronide (PdG) was evaluated for the indirect measurement of progesterone metabolites during the oestrous cycle and early pregnancy of uncaptured North American bison. Comparisons between plasma progesterone and urinary PdG, dose-response parallelism between the standard curve and diluted urine samples and high-performance liquid cochromatography revealed that PdG was a primary immunoreactive urinary metabolite of progesterone in bison. Urine samples were collected directly from the soil from 29 bison cows during the August rutting season and analysed for PdG. Eight bison cows demonstrated complete oestrous cycles ranging from 19 to 26 days (mean cycle length = 23.12 +/- 0.76 days) and behavioural oestrus among four of these cows correlated with PdG nadirs. Mean PdG nadirs were 63.62 +/- 21.61 ng/mg urinary creatinine (Cr) and mean peak midluteal values were 546.01 +/- 130.73 ng/mg Cr. Seven of eight became pregnant, indicating that bison exhibit a second seasonal oestrus. Eighteen other bison cows were pregnant prior to the beginning of the study and demonstrated non-cyclic increased PdG concentrations (greater than 200 ng/mg Cr) during the 30-day course of collection. Three cows ovulated and became pregnant during the 30-day collection period and then exhibited increasing urinary PdG concentrations. This report demonstrates that ovarian function in uncaptured bison can be monitored by means of urinary PdG and that both ovulatory cycles and early pregnancy can be detected.