Effect of recombinant human follicle-stimulating hormone or equine chorionic gonadotropin on the ovarian response in guinea pig.

This study evaluated the effect of recombinant human FSH/LH (r-hFSH/r-hLH) or equine chorionic gonadotropin (eCG) within two synchronization protocols on ovarian response in guinea pig. A total of 87 nulliparous females were used. Two synchronization protocols were performed (S1, S2). S1 involved oral administration of 0.4 mg/day altrenogest for 10 days, 0.0657 mg cloprostenol sodium intramuscularly on day 7, and 0.0013 mg buserelin acetate intramuscularly on day 10. S2 involved intramuscular injections of 0.0013 mg buserelin acetate on days 0 and 10, and 0.0657 mg cloprostenol sodium on day 7. Superovulation was induced using either r-hFSH/r-hLH (0.5 µg every 12 h from day 7 to 9 of the protocol) or a single dose of eCG (20 IU) on day 7. The experimental groups were: S1 - eCG, S1 - r-hFSH/r-hLH, S2 - eCG (n = 15 each), and S2 - r-hFSH/r -hLH (n = 12), plus control groups (S1 and S2, n = 15 each). Data were analyzed using a general linear model including synchronization protocol, superovulation treatment, and their interaction as fixed effects, and initial body weight as a covariate. Statistical analysis was conducted using RStudio v.4.4.2. Results showed that the ovulation rate was similar across almost all groups. However, the S2-r-hFSH/r-hLH group showed the highest number of corpora lutea (9.49 ± 0.90). The number of normal embryos recovered was similar between the S2-eCG and S2-r-hFSH/r-hLH groups. These findings suggest that applying the S2-eCG or S2-r-hFSH/r-hLH protocol in female guinea pigs increases the number of embryos recovered.