RESUMPTION OF OVARIAN FOLLICULAR ACTIVITY AND UTERINE INVOLUTION IN THE POSTPARTUM LLAMA

Resumption of ovarian follicle activity and uterine involution was stu died in the post partum llama. Thirty-nine adult multiparous llamas we re monitored by ultrasonography and analysis of urinary estrone sulfat e for 30 d post partum at the La Raya Research Station in Peru. Uterin e involution was measured in terms of reduction of length and diameter of both uterine horns. Correlation analysis was used to relate follic le size and concentration of estrone sulfate. Analysis of variance was used to determine rate of uterine involution relative to days post pa rtum. The left ovary was palpated and scanned by Day 3 post partum in contrast to Day 1 post partum for the right ovary. Ovulatory size foll icles, 7 mm, were present by Day 7.4 post partum (range 4 to 14 d). Fo llicle growth was detected as early as Day 4 post partum with follicle size being less during the first follicle wave (7.4 mm) compared to t he second and third waves (9 to 10 mm). Concentrations of urinary estr one sulfate were positively related (P<0.05) to follicular size, but t o a lesser degree during the first follicle wave (19.4 ng/mg Cr), than to the second wave (25.4 ng/mg Cr). Uterine involution, as measured b y diameter, was different between the left (gravid) and right (nongrav id) uterine horn (P<0.05) for the 17 d post partum, and was also diffe rent from that of control females for the 21 d post partum. Uterine in volution was complete in 63% of females by Day 21 post partum.