Effect of estradiol benzoate used at the start of a progestagen treatment on superovulatory response and embryo yield in lactating and non-lactating llamas

Oocyte Quality, In Vitro Fertilization and Embryo Development of Alpaca Oocytes Collected by Ultrasound-Guided Follicular Aspiration or from Slaughterhouse Ovaries

The morphological quality and the in vitro developmental competence of cumulus-oocyte complexes (COCs) collected from in vivo or slaughtered alpacas was compared. COCs were recovered from ovarian follicles using: (i) manual aspiration in ovaries of alpacas (n = 15) sacrificed at a local slaughterhouse, or (ii) transrectal ultrasound-guided follicular aspiration (or ovum-pick-up, OPU) in live alpacas (n = 13) 4 days after the administration of an ovarian superstimulation protocol (200 UI eCG). COCs recovered from both groups were morphologically evaluated and graded. Grade I to III COCs were in vitro matured for 26 h and in vitro fertilized afterwards for 20 h using fresh alpaca epididymal spermatozoa. Presumptive zygotes from both groups were in vitro cultured for 7 days. The proportion of COCs recovered over the total number of follicles punctured was similar between groups, but the mean number of COCs collected from individual ovaries was greater (p < 0.05) in slaughterhouse ovaries. A significantly higher (p < 0.05) percentage of low-quality COCs (grades III and IV) and a lower (p < 0.05) percentage of grade I COCs was obtained using OPU. The number of blastocysts, regarding cleavage and COCs collected, was higher (p < 0.007 and p < 0.0002 respectively) for COCs collected by OPU; however, the total number of blastocysts per female did not differ between groups. We can conclude that the recovery rate and morphological quality of COCs was significantly higher when follicles were manually aspirated from slaughterhouse alpaca ovaries; however, a statistically higher developmental potential was observed in oocytes collected by OPU from live alpaca donors.

Synchronization of time of development of ovarian follicular waves in South American Camelids

South American camelids (SAC) are induced ovulating animals. In unmated females, ovarian follicle development occurs in waves of growth and regression, while mating when there is the presence of a mature follicle leads to ovulation. The capacity to respond to an ovulatory stimulus depends on the stage of the follicular wave development. Treatments to control ovarian follicular development have been performed to synchronize timing of wave emergence and development of the dominant follicle at a predictable time. Thus, synchronization of the time of follicular wave development allows for performing fixed time mating or artificial insemination, and superestimulatory treatments for multiple follicule development. Protocols are based on removal of the suppressive effect of the dominant follicle, that can be achieved by physical ablation or by inducing ovulation (with LH or GnRH) or atresia (with progesterone or progestagens alone or combined with estradiol) of this follicle. Differences between treatments should be taken into consideration when choosing a protocol for fixed time mating or artificial insemination, especially when applying the use these technologies for SAC production by commercial enterprises. Furthermore, the objective of applying synchronization protocols should be considered, because not all of these are effective in inhibiting follicular growth before initiation of a superestimulatory treatment for multiple follicle development.

Plasma steroid profiles and ovarian response in llamas treated with eCG for superovulation combined with exogenous progesterone during early luteal phase

The objective of this study was to evaluate the effects of plasma progesterone (P₄) concentrations during eCG-ovarian follicular superstimulatory treatment performed in early luteal phase and estradiol concentrations during peri-ovulatory period on ovarian response, number and embryo quality. On Day -2, females (n = 75) having a follicle ≥7 mm were treated with GnRH to induce ovulation. On Day 0, females that had ovulations (n = 54) were treated with 1000 IU eCG and were assigned to one of two treatments: (1) intravaginal device (ID) containing 0.5 g P₄ (P₄ group) and (2) no ID (Control group). On Day 5, females were administered PGF_2α and the ID was removed. On Day 7 and 8, females were mated and embryo recovery was performed 7 or 8 days later. Blood samples were collected from Day 0 to 9. Number (± SD) of follicles ≥7 mm on day of mating was greater (P =  0.04) in the control (9.7 ± 4.2) than P₄-treated (6.7 ± 4.9) group; number of corpora lutea did not differ (5.5 ± 3.1 and 5.2 ± 3.4 respectively). Ovulation rate was greater (P <  0.01) in the P₄-group (77.4%; 130/168) than control group (53.3%; 135/253). Number of embryos with an excellent grade (grade 1) tended to be greater (P =  0.07) in the P₄-group (82.4%; 42/51) than control group (65.4%; 36/55). It was concluded that supplementation with exogenous P₄ during eCG treatment in early luteal phase inhibits excessive follicular growth, increases ovulation rate and improves embryo quality.

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.

Monitoring and controlling follicular activity in camelids

This paper reviews that state of our knowledge concerning follicular wave dynamics, monitoring and manipulation. All camelids have overlapping follicular waves in absence of ovulation which is induced by a seminal plasma factor (βNGF). The interval between follicular waves varies. The size of the ovulatory follicle varies between 11 and 25 mm in camels and between in 6 and 13 mm in South American Camelids. The interval between induction of ovulation and next ovulatory follicle is 15 ± 1 day for all camelids. Follicular activity is best monitored by transrectal ultrasonography. Progesterone therapy for 7-15 days seems to suppress follicular dominance but does not completely inhibit follicular recruitment. Combination of estradiol and progesterone seems to provide better control of follicular activity. Both methods have provided variable results in the synchronization of follicular waves. Combination of induction of ovulation with GnRH and luteolysis at predetermined times shows some promise in synchronization of follicular dominance. These synchronization protocols require further investigation in order to provide practical approaches for fixed-time breeding. Ovarian superstimulation with FSH and eCG alone or in combination is somewhat successful. The best results are obtained when treatment is initiated at the emergence of a new follicular wave after induction of ovulation or following treatment with progesterone for 7-14 days. However, response remains extremely variable particularly in terms of ovulation rate and number of recovered embryos. Sources of this variability need to be studied including the effects of season, nutrition, doses and frequency of administration of gonadotropin.