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

Two experiments were conducted to determine the effect of estradiol benzoate (EB) and intravaginal progestagen treatment on ovarian follicular dynamics and superstimulatory response in eCG-treated llamas. The purpose of Experiment 1 was to evaluate the effect of EB and progestagen treatment starting at different phases of dominant follicle (DF1) development on regression pattern and subsequent follicle wave emergence (WE2) in lactating and non-lactating llamas. Early lactating (n=24, 30+/-4 days postpartum) and non-lactating (n=24) females were assigned in equal numbers (n=8) to one of three groups according to the phase of DF1 (growing, static or regressing) determined by ultrasonography from day -3 to day 0. At day 0, llamas received an intravaginal sponge (MPA, 150 mg) and 5mg of MPA (i.m.). Half of the females (n=4) of each group were injected with 2mg (i.m.) of EB and half were not (control group). A 2 x 2 x 3 (lactational status, EB treatment and follicular phases) factorial design was used. Each sponge was removed 8 days later. Ovaries were monitored from day 0 to day 12. Daily blood samples were taken to determine 17beta-estradiol (E(2)) profiles from day 0 to day 8. The DF1 regression pattern was not affected (P>0.05) by the phase of follicle wave at the start of the treatment or any interactions among main effects. Follicle wave emergence in EB-treated llamas was delayed (P<0.05) by 2.3 days compared with non-treated llamas. Following EB treatment, plasma concentrations of E(2) were greater (P<0.05) from day 1 to day 5 in the treated than in non-treated females, but not from day 6 onward (P>0.05). Experiment 2 was designed to evaluate the effect of this treatment on the ovarian superovulatory response and embryo yield following eCG treatment administered on day of follicular wave emergence as determined in the Experiment 1. The same lactating (n=18, 61+/-4 days postpartum) and non-lactating (n=18) llamas at random stages of follicle wave were treated as those in Experiment 1 and received 1200IU of eCG at the time of WE2 (EB-treated=day 6.5 and non-treated=day 4.5). Llamas were mated 5 days after sponge withdrawal. A second mating was allowed 24h later. Embryos were collected between 7 and 8 days after the first mating and blood samples were taken to determine progesterone (P(4)) concentrations. The mean number of follicles on day of mating and the number of CL on day of embryo collection were not affected by lactational status, EB treatment or their interactions (P>0.05). Ovulation rate and mean (+/-SEM) number of recovered embryos for EB treatment group (67.5% and 2.4+/-0.4) were greater (P<0.05) than for no EB treatment (51.1% and 1.1+/-0.4). Plasma P(4) concentrations and number of CL per llama were correlated (r=0.49; P=0.014). In conclusion, progestagen plus EB treatment facilitates the prediction of the emergence of a new follicular wave approximately 6 days after treatment and resulted in a higher ovulation rate and embryo production in ovarian superstimulated llamas regardless of lactational status.

Fetal mortality diagnosis by ultrasound in the vicuña (Vicugna vicugna).

Ultrasonography is widely used in domestic species of camelids, but there is no information about the use of this technique for pregnancy diagnosis and determination of embryonic or fetal losses in the vicuña (Vicugna vicugna). The study was performed in 202 vicuñas (3-year-old females, n = 31; adult females, n = 171) mated during the summer months (January through March 2001) at the Abra Pampa Experimental Farm of Altitude in north-west Argentina. Transrectal ultrasound examination was performed in May (estimated 40-120 days of gestation) to determine the number of pregnant females. The pregnancy rate was 45.5% (92/202). No significant difference (P > 0.05) was observed between the pregnancy rate of 3-year-old females (41.9%) and adult females (46.2%). In December (estimated 250-330 days of gestation) of the same year, a second ultrasonographic study was performed on those vicuñas that were diagnosed as pregnant from the first ultrasound scan. Of 92 animals diagnosed as pregnant in May, only 84 were present in December, because eight females died in the period of study. Overall, 11.9% (10/84) of fetuses were lost during the period (18.1% in 3-year-old vicuñas and 10.9% in adult vicuñas). In conclusion, transrectal ultrasonography was found to provide a rapid and non-invasive means for pregnancy and fetal mortality diagnosis in vicuñas.

Successful transfer of vitrified Ilama (Lama glama) embryos.

The exploitation of the domestic animals species of South American camelids is of great social importance for the native people living in the High Andes. The reproductive physiology of these species is a unique challenge in the development of advanced breeding techniques. At present, the cryopreservation of embryos has not been developed and very few investigations have been conducted. The objective of the present work was to evaluate the in vivo survival of vitrified llama embryos after transfer to recipient females. Donors females were treated with a CIDR-estradiol benzoate-eCG regimen and were mated naturally 6 days after CIDR withdrawal. One ovulatory dose (8 microg) of GnRH was administered immediately after mating. A second mating was allowed 24 h later. Embryo recovery was performed nonsurgically between 8 and 8.5 days after the first mating. Twenty-two ova/embryos were recovered from 12 donor females. Hatched blastocysts were exposed to vitrification solution (20% glycerol + 20% ethylene glycol + 0.3 M sucrose + 0.375 M glucose + 3% polyethylene glycol (P/V)) in three steps, and after loading into 0.25 ml straws, were plunged into liquid nitrogen. For embryo transfer, recipients animals were ovulation-synchronized using GnRH administered at the same time as donors. A total of eight vitrified-warmed embryos and 12 fresh embryos were nonsurgically transferred to four and six recipient females, respectively (two embryo per recipient). The pregnancy rates were 50 and 33.3% for recipients that had received vitrified embryos and fresh embryos, respectively. The results demonstrated the effectiveness of this simple vitrification method for cryopreservation of llama embryos.