Superovulatory response and embryo production using a bioactive recombinant equine chorionic gonadotropin in sheep.

BRUNO GALARRAGA, MARÍA MACARENA;; FERNANDEZ J; CUETO MARCELA; CATTANEO L; PRIETO C; ANTUÑA C; TARDIVO C; FONTANA B; BO G; ALEJANDRO GIBBONS

Conferencia; 44º Annual Conference of the International Embryo Transfer Society (IETS).; 2022

IETS

The development of a new recombinant equine chorionic gonadotrophin (reCG) evaluated in cows has recently been published (Villarraza et al., 2021). The objective of this study was to evaluate the potential of reCG on the induction of superovulatory response and embryo production in sheep. The study was carried out in the Laboratory of Reproduction in Small Ruminants of INTA Bariloche during the breeding season (May, 41º S latitude). Merino sheep (n=24; 4 years old; body weight of 41.5 ± 2.5 kg and body condition score of 2.5 ± 0.2) were treated with intravaginal sponges (60 mg MAP Progespon®, Syntex, Arg) for a period of 14 days. At the time of sponge removal, ewes were asiggned randomly to two treatments to receive a single dose of 280 IU (reCG280, n=11) or 420 IU (reCG420, n=13) of reCG (FOLIREC®, Zoovet, Arg). Estrus detection was performed every 12 h, from 24 h to 48 h after sponge removal, using an adult teaser ram. Forty eight hours after sponge removal, laparoscopic intrauterine insemination with frozen/thawed semen (100×106 sperm per ewe) from a single ram of proven fertility was performed only in ewes that showed estrus. On Days 7 and 8 after sponge removal, the number of corpora lutea (CL) was assessed by laparoscopic observation. Embryo recovery was carried out using the technique described by Gibbons et al. (2011). The collected embryos were classified morphologically based on the guidelines of the IETS. The ovulatory response and embryo production were compared between treatments using ANOVA test. Data are presented as means ± standard error mean. A total of 91.6% ewes were observed in estrus (22/24) between 24 and 48 h after sponge removal (9 and 13 ewes for reCG280 and reCG420, respectively). Both dosages were able to induce superovulation and no differences were detected in all the end points evaluated (Table 1). This study reports for the first time that recombinant eCG can produce an acceptable superovulatory response and good embryo production in sheep. These results have important implications as an alternative for control of the ovulatory response using a synthetic recombinant hormone without the need of using animals for its manufacture.