Effects of short-term intravaginal progestagens on the onset and features of estrus, preovulatory LH surge and ovulation in sheep

Abstract

In the present study, there was a comparison among classical long-term progestagen (fluorogestone acetate) protocols for synchronization of estrus and ovulation (14 days; group FGA14, n = 9 ewes) and short-term protocols based on 7 days of progestagen treatment plus a dose of prostaglandin F at either insertion (PG-FGA7, n = 11) or removal (FGA7-PG, n = 12). There were no significant differences in the ovulation rate and progesterone secretion among treatments. The FGA7-PG group, however, had a similar percentage of ewes expressing estrous behavior than the group FGA14 (90.9 and 100%, respectively, with a trend for a lesser percentage in the PG-FGA7 group, 63.6%) and about 90% of the ewes in the FGA7-PG group had the preovulatory surge release of LH 8 h after the onset of estrous behavior. These features may be related to a greater number of preovulatory follicles during growing phases (P < 0.05) and a greater plasma estradiol concentration (P < 0.05) in this group than in the classical 14-day group, which suggest these are more functional preovulatory follicles. In conclusion, therefore, the use of the FGA7-PG treatment may favor efficiency of progestagen-based protocols for reproductive management.

Influence of Progesterone-Treatment Length and eCG Administration on Appearance of Estrus Behavior, Ovulatory Success and Fertility in Sheep

“…These patterns of follicular dynamics after inducing high plasma progesterone levels would also explain the delay of estrus and ovulation in short-term treatments when compared to long-term treatments, due to the need for the development of a new follicular wave from which ovulatory follicles arise. The same effect has been found after the administration of progestagen-impregnated sponges [9] and even after the administration of a single intramuscular dose of progesterone [23]. Such an effect is not critical when applying natural mating, but needs to be taken into account when implementing artificial insemination at a fixed time.…”

“…These alterations were later related to the prolonged time of treatment permanence, and these findings supported the use of short-term (5–7 days) progestative treatments [6,7,8]. Currently, short-term protocols are recognized to be equally as effective as long-term protocols for inducing estrus, ovulation, and fully functional corpora lutea [9], with lower incidence of vaginal infections [10] and higher fertility yields [11].…”

Use of GnRH for Synchronization of the Follicular Wave in Assisted Reproductive Technologies in Sheep: A Preliminary Study

“…Currently, such knowledge is giving way to “follicle-focused” protocols [ 15 ]. These protocols consist of short-term progestative treatments (5–7 days), which are equally as effective as long-term protocols for inducing preovulatory events and ovulation [ 16 , 17 ], with even a higher fertility [ 2 , 18 ]. Short-term protocols aim to synchronize estrus and ovulation but also the follicular wave from which the ovulatory follicles arise.…”

Onset of oestrus and periovulatory events in sheep exposed to 5 and 14 days of CIDR treatment with and without eCG

“…Short‐term protocols (5–7 days of progesterone insertion) are increasingly used since they are equally as effective as long‐term protocols for inducing ovulation and fully functional corpora lutea (Martinez‐Ros, Astiz, Garcia‐Rosello, Rios‐Abellan, & Gonzalez‐Bulnes, ), with lower incidence of vaginal infections (Martinez‐Ros, Lozano, et al, ) and higher fertility yields (Menchaca, Santos‐Neto, Cuadro, Souza‐Neves, & Crispo, ; Swellum, Alowaimer, & Abouheif, ).…”