Corpus luteum vascularization during the maternal recognition of pregnancy in llamas (Lama glama).

The aim of this study was to characterize corpus luteum vascularization and its association with plasma progesterone concentration in early stages of pregnancy, when maternal recognition of pregnancy is expected to occur. In all animals, both plasma progesterone concentration and corpus luteum vascularization increased from Day 6 to Day 8 post-mating and afterwards in non-pregnant llamas they started to decrease to reach basal levels around Days 12 to 14 post-mating, while in pregnant animals, both variables remained elevated until the end of the study. A lineal positive relationship between corpus luteum vascularization and plasma progesterone concentration was observed in pregnant (r2  = .46, p < .0001) and non-pregnant llamas (r2  = .66, p < .0001). Pregnant animals showed higher plasma progesterone concentration and corpus luteum vascularization than the non-pregnant ones from Day 12 post-mating until the end of the study (p Ë‚ .05 and p Ë‚ .01, respectively). These results suggest that maternal recognition of pregnancy should occur before Day 12 post-mating in order to expand luteal lifespan, maintaining corpus luteum vascularization and progesterone production. Also, the assessment of CL vascularization area could be a useful and non-invasive method for early pregnancy diagnosis due to its association with plasma progesterone concentration.

Administration of progesterone BioRelease LA inhibits follicular growth in llamas (Lama glama) regardless of follicle diameter at the start of treatment.

The aims of the study were twofold: first, the comparison of the pharmacokinetics parameters of two doses of Progesterone BioRelease® LA, (BioRelease Technologies, Lexington, KY, USA) one of 300 mg and other of 150 mg and their effects on ovarian dynamics in llamas. Based on the results from the first study, the aim of the second study was to evaluate the effect of the doses of 150 mg of progesterone on follicular activity considering the stage of the largest follicle at the beginning of treatment. The results in Study 1 showed that both doses of the formulation induced plasma progesterone concentrations higher than 1 ng/ml during the first 6 days of treatment in all females, progesterone concentrations steadily decline until Day 5 following by a slowly decrease. The total amount of progesterone released during treatment was higher in Group 300 than in Group 150 (p = 0.045). Mean maximum concentrations were 14.9 ± 2.24 and 14.3 ± 2.16 ng/ml for Group A versus Group B (p = 0.58), and they were registered on Day 1.5 ± 0.22 and 1.7 ± 0.34 days, respectively (p = 0.10). None of the animals of Group A showed progesterone concentration below 1 ng/ml during all studied period. The treatment applied in Study 2 was efficient in inhibiting the ovarian follicular dynamics and to start a superestimulatory treatment. The use of progesterone Biorelease® LA of 150 mg in comparison with the dose of 300 mg could be more effective in the use of synchronization protocols in llamas for AI or prior to the application of an ovarian superstimulatory treatment.

Embryo transfer technique: Factors affecting the viability of the corpus luteum in llamas.

The aim of the present study was to evaluate the effect of the embryo transfer (ET) maneuvers on plasma progesterone concentrations in recipient Lama glama females and the relationship between the site the embryo was transferred to and corpus luteum (CL) localization. Experiment I (effect of transcervical threading): adult non-pregnant, non-lactating llama females were randomly assigned into two groups: control group (without cervical threading, n=10) and group A (with cervical threading, n=10). In both groups, CL activity was evaluated through measurement of progesterone plasma concentrations. In group A, on Day 6 after inducing ovulation with buserelin, the cervix was threaded to evaluate the effect of the maneuver on CL viability. No significant differences were observed in mean progesterone concentrations between groups (P>0.05). Experiment II (effect of depositing PBS): females (n=66) were randomly assigned into six groups (n=10 per group and control group: n=6) to evaluate the effect of depositing PBS in different sites in the uterus in relation to the localization of the CL: group 'Left-Ipsilateral': transcervical placing of PBS in the left uterine horn (CL in left ovary); group 'Left-Contralateral': transcervical placing of PBS in the left uterine horn (CL in right ovary); group 'Right-Ipsilateral': transcervical placing of PBS in the right uterine horn (CL in right ovary); group 'Body-Left': transcervical placing of PBS in the uterine body (CL in left ovary); group 'Body-Right': transcervical placing of PBS in the uterine body (CL in right ovary) and control group. Corpus luteum activity was evaluated in all groups by measuring plasma progesterone concentrations. On Day 6 post-buserelin, the corresponding maneuver was carried out according to the group. No significant differences were found for the mean plasma progesterone concentrations between groups (P>0.05). Experiment III (effect of ET on CL viability): females (n=22) were used as embryo donors and 50 females as recipients, in order to evaluate if placing the embryo in different areas of the uterus influences CL viability. Recipients were randomly divided into five groups, according to the place in the uterus where the ET was conducted with respect to the ovary where ovulation occurred: group 'Left-Ipsilateral': ET in the left uterine horn (CL in left ovary); group 'Left-Contralateral': ET in the left uterine horn (CL in right ovary); group 'Right-Ipsilateral': ET in the right uterine horn (CL in right ovary); group 'Body-Left': ET in the uterine body (CL in left ovary) and group 'Body-Right': ET in the uterine body (CL in right ovary). Corpus luteum activity was evaluated in all groups by measuring plasma progesterone concentrations. Embryos were recovered by flushing the uterus on Day 8 after the first mating of the donor and transcervical ET was carried out in recipients 6 days after buserelin administration. Pregnancy rates were: group 'Left-Ipsilateral': 50%; group 'Left-Contralateral': 20%; group 'Right-Ipsilateral': 30%; group 'Body-Left' and 'Body-Right': 10%. No significant differences (P=0.4728) were detected between the pregnancy rates in the five groups. Threading the cervix and transcervical placing of PBS either in the uterine horns or the body did not affect plasma progesterone concentrations in the llama, indicating that the different embryo transfer maneuvers do not interfere with CL viability. To improve pregnancy rates it could be suggested that ET in the left uterine horn with an ipsilateral CL, is the most desirable option.