Pharmacodynamic evaluation of biodegradable estradiol-17#beta#microspheres and prostaglandin F2_#alpha# for the control of estrus and ovulation in gilts

摘要

Currently in the United States there are no approved products for use regulating the estrous cycle in breeding pigs. Thus, estrus regulation and scheduled breedings must be done using alternative infefective management techniques or allowing nature to take it's course, which both result in obvious inefficiencies and inconveniences, especially in gilt management. The opportunity to develop and capitalize on controlled-breeding programs in the swine industry now exists with the emergence of controlled release pharmaceutical technology for inducing pseudopregnancy in gilts. The emerging treatment uses controlled release estradiol-17#beta# (E2) to induce pseudopregnancy, which blocks the normal return to estrus because of continued progresterone (P_4) secretion by the corpus luteum (CL) from the previous ovulation, as occurs in normal pregnancy. The objective of the present study was to examine if modification of the estradiol-17#beta# (E2) component of a currently developed single injection controlled release microsphere formulation, developed for use in horses, could reliably induce pseudopregnancy following gonadotropin-induced pubertal ovulation in 180 day old gilts. Four doses of estradiol microspheres were evaluated in this study. Additionally, the study examned the effectiveness of PGF_(2#alpha#) for induction of luteolysis and a controlled estrus on Day 59 of pseudopregnancy in gilts previously treated with controlled release estradiol.