Effects of Corpora Lutea Removal and Replacement with Progesterone on Pregnancy in Goats

Abstract

Laparotomies were performed on 21 goats either on the 100th or 125th day of gestation. All or some of the corpora lutea were removed from 19 goats and the entire ovaries were removed from two goats. Eight goats received no further treatment while 13 goats were injected daily with 25, 15 or 10 mg. of progesterone. Excision of all the corpora lutea in four goats and of both ovaries in one goat resulted in prompt abortion two days later, confirming the need for the corpora lutea during the last third of pregnancy in goats. In 20 of the 21 goats the number of corpora lutea found in the ovaries corresponded to the number of fetuses. Excision of only one of two corpora permitted three goats with two fetuses each to continue in pregnancy for variable periods of time, indicating that more progesterone is normally secreted by the corpora lutea than necessary to maintain gestation. When all the corpora lutea were removed, subcutaneous injections of 25 mg. of progesterone daily maintained pregnancy in three of three goats, 15 mg. in four of four goats and 10 mg. in four of six goats. It is concluded that the progesterone requirements of goats is of the order of 10 mg. daily during the last third of pregnancy.