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摘要
Twelve non pregnant and non lactating sexually mature llamas were i.m. injected on day 0 with 2.5 mg of EB (EB group, n = 6) or ECP (ECP group, n = 6). Blood samples were collected immediately before injection, at 1, 6, 12, 24 h after treatment and then daily until day 14 post injection. Changes in hormone concentrations with time were analyzed in each group by analysis of variance (ANOVA) using a repeated measures (within-SS) design. Plasma E2 concentrations and area under the concentration-time curve (AUC) values were compared between groups by ANOVA. In all cases a Least-Significant Difference test (LSD) was used to determine differences between means. Hormonal and AUC data are expressed as mean ㊣ S.E.M.Peak plasma E2 concentrations were achieved earlier and were higher in EB group than in ECP group. Thereafter, E2 returned to physiological concentrations earlier in EB group (day 5) than in ECP group (day 9). Although plasma E2 profiles differed over time among groups there were no differences between them on AUC values.The i.m. injection of a single dose of both oestradiol esters resulted in plasma E2 concentrations exceeding physiological values for a variable period. Moreover, the plasma E2 profiles observed depended on the derivative of oestradiol administered. This basic information becomes relevant at defining treatment protocols including oestrogens in llamas.Llamas (Lama glama) are ruminants with physiological peculiarities, particularly regarding their reproductive physiology. Ovarian follicles develop in a wave-like pattern as in other ruminants: cows [1]; ewes [2]; goats [3], but the process of ovulation requires the stimulus of mating and ejaculation [4-8]. Moreover, only growing, dominant follicles ≡ 7 mm in diameter present at the time of mating have the ability to ovulate [9]. In the absence of ovulation, successive waves of follicular growth and regression that generally overlap, proceed [10,11]. The oestrogens produced during those waves determin