Use of a combination of synthetic oral progesterone and prostaglandin F2-alpha for ovulation induction protocols in Chinchilla lanigera

CANTARELLI V; MASTROMONACO G; PONZIO M.F

virtual

Congreso; nternational Society of Wildlife Endocrinology Virtual Event.; 2021

nternational Society of Wildlife Endocrinology

Altrenogest is a synthetic oral progesterone agonist used in farm animals as pre-treatment for suppressing the natural estrous cycle, thus mimicking an extended luteal phase for as long as the progestin is administered. Because progesterone has an inhibitory effect on the release of LH, the rationale is to artificially maintain an elevated concentration of progesterone until the corpora lutea regresses. Following withdrawal, estrus and ovulation should occur at a predictable time. The effectiveness of this synthetic progestagen was evaluated in an ovulation induction protocol for Chinchilla lanigera applied together with prostaglandin-F2α (PG-F2α).Two i.m. injections of PG-F2α (100 µg cloprostenol-sodium; Ciclase-DL) were applied 7 days apart to sixteen females. During those 7 days, 0.1 mg/kg/day of altrenogest (Progestal) was orally administrated to each animal. Half of the females also received 100 U.I. of eCG (Novormon-5000) at time of the second PG-F2α dose. All urine samples produced by the animals were collected one week before, during and one week after the injections. Samples were analyzed for creatinine (CRT, Sigma #C3613), pregnanediol glucuronide and estrone conjugates (PdG-R13904, EC-R522-2, C.Munro) by EIA. The results obtained in both protocols showed that altrenogest applied with PG-F2α successfully suppressed ovarian activity evidenced by the basal EC and PdG concentrations observed during the days of administration, with the exception of a slight increment in PdG levels in one of the protocols, attributed to oral administration of the synthetic progestagen, which is excreted mainly as PdG. After altrenogest withdrawal, an increase in EC and PdG levels as sign of ovarian activation, was observed only in the protocol that also included an eCG injection. It is likely that the altrenogest dose administered was too high and probably produced an excessive reduction in ovarian activity and therefore, the progesterone withdrawal alone was not enough to induce ovulation