A practical approach to evaluation of fertility in the female gorilla



Measurements of urinary estrogen, pregnanediol-3-glucuronide, and bioactive luteinizing hormone indexed by creatinine on a daily basis in female gorillas reflect ovarian function. The use of small urine samples obviates the need for capture, restraint, or isolation and provides the basis for a nonstressful evaluation of reproductive status or fertility. Initial attempts at artificial insemination have thus far been unsuccessful when the fertile period was predicted by urinary estrogen and pregnanediol-3-glucuronide evaluations. The cause of these failures cannot be attributed to any one factor, but hormone profiles suggest that insemination preceded ovulation by more than one week in both cases. The prolongation of the follicular phase in conjunction with both inseminations when compared to all follicular phase intervals in the same individual (30 and 32 vs 21.8 ± 2.4 (mean ± SE; n = 10) days, respectively) may indicate a delay of ovulation as a result of the physical manipulation of the female.