The aim of the present study was to evaluate the application of a GnRH-PGF_2α based synchronization and superstimulation protocol for fixed-time natural mating in llama embryo donors. All females (n = 8) received 8 μg IM of GnRH analog (GnRHa; buserelin) on day 0, regardless of follicular status. After eight days, another GnRHa dose was administered followed by 250 μg IM PGF_2α (cloprostenol). A dose of 1000 IU IM of equine chorionic gonadotrophin (eCG) was applied on day 12 and a new dose of PGF_2α was administered on day 13. All embryo donors were mated with a male of proven fertility followed by a GnRHa dose on day 18. 24 h later, mating was repeated with a different male. Transcervical uterine flushing for embryo recovery was carried out on all females on day 26. Recipient females received one dose of GnRHa (day 0) two days after the first mating of embryo donor females. A 75% (6/8) of embryo donors responded to the superstimulation treatment with a range of 2 to 5 corpus luteums (CLs) on embryo recovery day. A total of 24 CLs were registered, with a mean of 4 ± 0.9 CLs per female. Embryo recovery rate was 66.7% (16/24), with a range of 0 to 4 embryos and a mean of 2.7 ± 1.5 embryos per female. Regarding quality of the recovered embryos, 56.2% were grade I, 6.2% were grade II and 37.5% were grade V (untransferable; arrested morulae). Grade I and II embryos (n = 10) were transcervically transferred into recipient females (n = 10) six days after inducing their ovulation. At 24 days after embryo transfer (ET), a 50% pregnancy rate was registered. In conclusion, a group of llama embryo donors can be synchronized and superstimulated using a fixed-time mating protocol based on GnRHa, PGF_2α, and eCG without the necessity of using ultrasonography in the field.

本研究的目的是评估基于GnRH- _PGF2α的同步化和超刺激方案在美洲驼供体中固定时间自然交配的应用。所有女性（ñ= 8）在第0天接受了8μgIM的GnRH类似物（GnRHa; buserelin），无论卵泡状态如何。八天后，再次给予GnRHa剂量，然后再给予250μgIM _PGF2α（氯前列醇）。在第12天应用了1000 IU IM的马绒毛膜促性腺激素（eCG）剂量，并且新剂量的_PGF2α在第13天施用。所有胚胎供体与已证实具有生育力的雄性交配，然后在第18天给予GnRHa剂量。24小时后，与另一雄性重复交配。在第26天，对所有雌性进行子宫颈子宫冲洗术以恢复胚胎。在雌性首次捐献雌性交配两天后，接受雌性的雌性接受一剂GnRHa（第0天）。在胚胎恢复日，有75％（6/8）的胚胎供体对超刺激治疗产生了2至5个黄体（CL）的反应。总共注册了24个CL，平均每个女性为4±0.9个CL。胚回收率为66.7％（16/24），范围为0至4个胚胎，平均每位雌性为2.7±1.5个胚胎。关于回收的胚胎的质量，I级为56.2％，II级为6.2％，V级为37.5％（不可转移；桑被捕）。ñ = 10）经子宫颈转移到女性接受者中（ñ= 10）诱导排卵后六天。胚胎移植（ET）后24天，妊娠率达到50％。总之，可以使用基于GnRHa，PGF2α和eCG的固定时间交配方案对一组美洲驼胚胎供体进行同步和超_刺激，而无需在现场使用超声检查。