Control of ovarian activity in llamas (Lama glama) with medroxyprogesterone acetate

Progesterone and progestogens have proved to be effective in controlling fo llicle development and synchronization of ovarian activity in different spe cies. In this study, vaginal sponges containing 120 mg medroxyprogesterone acetate were used to synchronize ovarian activity in Ilamas and to predict the time when a mature follicle will be present. Plasma concentrations of o estradiol-17 beta and progesterone were measured to determine follicle and corpus luteum development. The sponges were kept in the vagina for 9 days. Six days after sponge withdrawal, ovulation was induced by either GnRH inje ction (n = 4), mating with a vasectomized male (n = 8) or mating with an in tact male (n = 10). Plasma progesterone concentrations varied between anima ls until day 6 after insertion of the sponges. Thereafter, progesterone lev els remained close to the detection limit of the assay until ovulation was induced. The mean oestradiol-17 beta plasma concentration reached its lowes t value 3-4 days after insertion of the sponges. Thereafter, concentrations increased and reached peak levels at day 6 after withdrawal of the sponges . All animals ovulated and developed a corpus luteum with a normal life spa n after the ovulatory stimulus. Blood samples were collected frequently aft er mating to evaluate the endocrine response to copulation. Plasma concentr ations of PGF(2 alpha) metabolite and cortisol increased in parallel after copulation. The metabolite concentrations returned to basal levels 3-4 h af ter mating whereas the cortisol concentrations remained elevated For about 12 h after copulation The luteinizing hormone secretory pattern resembled t hat reported when Ilamas with a mature ovulatory follicle were mated. In co nclusion, the protocol evaluated in this study was shown to be useful for t he synchronization of ovarian activity and for predicting the time when an ovulatory follicle will be present in Ilamas.