16 FERTILITY RATE OBTAINED WITH A NEW INTRAVAGINAL PROGESTERONE RELEASING DEVICE DICO IN SHEEP

Abstract

A new intravaginal device DICO (Dispositivo Intravaginal Caprino Ovino, 0.3 g progesterone; Syntex, Buenos Aires, Argentina) consisting of a progesterone impregnated medical silicone was developed for oestrus synchronization in sheep and goats. The effectiveness of this device to control serum progesterone concentrations, follicular development and time of ovulation has been recently reported in ewes (Vilariño et al. 2010 Small Rumin. Res. 91, 219–224); however, fertility obtained with DICO has not been evaluated yet. The aim of this study was to determine fertility rate obtained with DICO by fixed-time cervical or intrauterine insemination in sheep. The experiment was performed on a total of 569 Corriedale multiparous ewes in breeding season, with a body condition score of 3.0 ± 0.1 (scale 0–5). Ewes received a Short-term Protocol consisting of a 6 days of treatment with DICO (n = 174), CIDR-G (0.3 g of progesterone, Pfizer, NY, USA; n = 197) or sponges with 60 mg of medroxiprogesterone acetate (MAP, Syntex; n = 198). One dose of prostaglandin F2α analogue (125 μg of cloprostenol, Cilcase DL, Syntex) and 300 IU of eCG (Novormon, Syntex) was given at the time of device withdrawal. Insemination was performed 48 or 54 h after device removal by cervical (200 millions of spermatozoa) or laparoscopic intrauterine insemination (100 millions of spermatozoa), respectively. Pregnancy diagnosis was performed by transrectal ultrasonography (5 MHz, Well D, Beijing, China) 40 days after insemination. Pregnancy rate (pregnant ewes/inseminated ewes) was compared by logistic regression, and number of fetuses/pregnant ewes was analysed by Poisson regression. Regarding pregnancy rate, a significant difference (P < 0.05) was found between cervical (39.5%, 109/276) v. intrauterine insemination (58.3%, 172/295), as well as between progesterone devices (DICO: 55.7%, 97/174; CIDR-G: 55.8%, 110/197) v. MAP sponges (37.4%, 74/198). The results are shown in Table 1. In conclusion, the current study shows that the new intravaginal device DICO is useful to obtain acceptable fertility with fixed-time insemination in sheep. When cervical insemination at 48 h or intrauterine insemination at 54 h after device removal is performed, similar or better results than CIDR-G or MAP sponges are achieved, respectively.

Table 1.  Results obtained with DICO, CIDR and sponges after cervical or intrauterine insemination in sheep