BIBLIOGRAPHIC STUDY: PROTOCOLS FOR THE INDUCTION OF OVULATION IN THE MARE

Abstract

Although various regimes are available, some are sp ecific to cycling mares during the ovulatory season and noncycling mares during anovulatory or transitional season and early postpartum . In this regard this paper discusses and summarizes the basi s for the use of some regimens for controlling ovul ation in the mare. For controlling the estrous cycle of the cycling ma re there are some conventional regimens and novel methods. Before beginning any regimen with the help of ultrasonography or transrectal palpation the reproductive tract sho uld be assessed and then a decision about when to use one regimen over another can be taken. The most common hormonal treatments used in the regimens are presented below. The natural form of PgF2 α and some of its analogues have been used in mares to induce luteal regression and hasten estrous and ovu lation. Treatment with native PgF2 α (dinoprost, 5-10 mg/dose 36 ) may induce some undesirable side effects , that's why analogues (cloprostenol ,100-250 �g/dose 36 ; luprostiol 7,5 mg/dose 3 ) that produce less side effects but with a potent luteolytic action are sometimes prefe rred .Treatment with PgF2 α can be done by any parentheral routes , but the most common used i s the intramuscular injection. A recent study involved administration of PgF2 α at one-tenth the conventional dose (dinoprost ,0.5 mg) into the sacral-lumbar space at mid-diestrus 1 .Results indicated a significant and sustained decrease in systemic levels of progesterone 24 hour s after the sacral-lumbar injection, witch was similar to the changes obtained in mares that r eceived the conventional dose intramuscular. A regimen for the induction of ovulation consists i n a PgF2 α injection (day1) followed by an hCG treatment (day 7-8) and another PgF2 α administration (day 15) followed by hCG treatment (day 21-22).The interval between the end of the treatment and the ovulation time is of 2-4 days 17