INTRAUTERINE INFUSION OF PROSTAGLANDIN-E2 AND SUBSEQUENT LUTEAL FUNCTION IN CATTLE

The objective was to evaluate the effect of intrauterine infusion of prostaglandin E2 (PGE2) on luteal function in cattle. Heifers and cows were randomly assigned after two normal estrous cycles to either PGE2 or control treatment groups. Females in Treatment A were infused with 1 mg of PGE2 once daily into the uterine horn ipsilateral to the corpus luteum between days 7-10 of the estrous cycle with a 0.25 ml plastic semen straw and an artificial insemination pipette. Females in Treatment B were similarly infused with 1 mg of PGE2 once daily in 20 ml of a carrier vehicle via a catheter on days 10 and 11 of the estrous cycle. Control animals were infused with the carrier vehicle using either a semen straw (Treatment C) or via a catheter (Treatment D) on the same days of the estrous cycle. Blood samples were collected daily to monitor plasma progesterone concentrations during the treatment period. Females infused with PGE2 on days 7-10 of the estrous cycle returned to estrus in a mean of 23.5 days (range 22-25 days) and were similar (P>0.05) to those infused on days 10 and 11 which returned to estrus in 23.5 days (range 22-25 days). Animals similarly infused with carrier vehicle on the same days of the estrous cycle returned to standing estrus in 20.2 days (range 17-23 days). Plasma progesterone concentrations indicated an extended period of elevated progesterone concentrations in PGE2-treated animals compared with control animals. These results indicate that short term administration of PGE2 early in the estrous cycle may result in extended luteal maintanance.