Control de la dinámica folicular ovárica en Llamas (Lama Glama) en posparto temprano

Se evaluó el efecto del acetato de medro-xiprogesterona (AMP, esponja intravaginal) con o sin inyección de benzoato de estradiol (BE) sobre el patrón de regresión folicular, la emergencia de la onda folicular y la tasa ovulatoria en llamas en posparto temprano y sin cría. El trabajo se realizó en la Estación Experimental de Altura del INTA de Abra Pampa, ubicada a 3484 msnm. Un total de 48 llamas adultas fueron categorizadas en lactancia temprana (n= 24, 30±4 días posparto, media±DE) y sin cría (n= 24). Cada hembra fue distribuida de acuerdo a la fase folicular (FF= crecimiento, estática o regresión) del folículo dominante (FD1) determinada por ultrasonografía ovárica desde 3 días previos al tratamiento. El día 0, todas las hembras recibieron una esponja intravaginal (150 mg de AMP) durante 8 días más 5 mg AMP (im) y la mitad de las hembras recibió aleatoriamente 2 mg de BE (im). Desde el día 0 hasta el 14, la respuesta ovárica fue monitoreada diariamente por ecografía. El día 12, las hembras que presentaron un folículo dominante ³6 mm (FD2) de una nueva onda folicular fueron tratadas con GnRH (8 mg, im) para inducir la ovulación. Se midió la concentración plasmática de 17b-estradiol (desde el día 0 al 8) y progesterona (día 14) para confirmar la ovulación. Se utilizó un diseño factorial 2x2x3 (estado lactacional, tratamiento con o sin BE y fases foliculares). Se observó interacción entre el estado lactacional y la fase folicular sobre el patrón de regresión del FD1, atribuida a una mayor duración en hembras sin cría (6,0 días) que en las hembras con cría (3,5 días) durante la fase estática. El día de emergencia del FD2 fue diferente (p

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.