Bioequivalencia en ganado bovino de una glicoproteína similar a la gonadotrofina coriónica equina (eCG-like) producida mediante tecnología recombinante.

The objective of this study was to determine the bioequivalence in bovines in superovulatory, superstimulatory and fertility in an TFAI protocol between a single-chain equine chorionic gonadotropin produced by recombinant technology (eCG-like) and native eCG. In Experiment 1, a crossing over experimental design was used where 14 cows received 2,000 IU im of eCG or 2,000 IU im of eCG-like on Day 4 of a superovulatory protocol in two periods. The cyclicity, size of the preovulatory follicles (PF), the number of accumulated ovulations (AO) and the number of corpora lutea (CL) were determined by ultrasonography. Experiment 2 was performed to evaluate the pregnancy rate in beef cows, where 828 cows received a protocol based on P4 and estradiol, and on Day 8 (removal of the intravaginal device) they were assigned to receive 400 IU of eCG-like (n=278), 400 IU of native eCG (n=301) or remain as untreated controls (n=249). In Experiment 3, the percentage of pregnancy at TFAI in dairy cows (n=472) was evaluated, where the same TFAI protocol based on progesterone and estradiol was used, and on Day 8, the cows were assigned to receive 400 IU of eCG-like (n=187) or 400 IU of eCG (n=194) or remain control (n=91). In Experiment 1, there were no differences in the number of FPs, the number of AO, the number of CL. In Experiment 2, the pregnancy rate at IATF was 29.7%, being higher in the groups treated with eCG and eCG-like compared to the control: 31.6%, 32.4% and 24.5% respectively (P=0.0391). In Experiment 3, the follicular diameter on day 10 was greater in cows treated with eCG and eCG-like (P=0.0007) and the IATF pregnancy rate was 38.6% and was affected by the treatment (P= 0.0335). We conclude that single-chain eCG-like produced by recombinant technology demonstrated a similar biological response in cattle at the same dose as eCG, being the first report where bioequivalence has been demonstrated in cattle. [ABSTRACT FROM AUTHOR]