241 Responsiveness of guinea pigs treated with recombinant human gonadotrophin hormone within a short superovulation protocol

Efforts have been made to achieve the ovarian superstimulation of guinea pigs in a short superovulation protocol. This study was carried out to assess the applicability of recombinant human follicle stimulation hormone (r-hFSH) with or without recombinant human luteinising hormone (r-hLH) for inducing ovarian superstimulation of guinea pigs in a short superovulation protocol (10 days). 13 nulliparous female guinea pigs of 60 days of age were distributed in two different groups. Group 1: six female guinea pigs were treated with altrenogest (Regumate^®, Merck Animal Health USA) (0.8 mL/day) orally per 10 days, at Day 8, 0.15 mL of cloprostenol sodium (Lutaprost^®250, Agrovet Market) was injected intramuscularly. In addition, for inducing the ovarian superstimulation, 0.5 µg of r-hFSH/r-hLH (Pergoveris^®, Merck Europe B.V.) was injected subcutaneously each 12 h at Days 8, 9, and 10 of the protocol. To ensure ovulation, 0.1 mL of buserelin acetate (Conceptase^®, Agrovet Market) was injected intramuscularly at Day 10. The superovulation treatment for Group 2 (n = 7 animals) replaced r-hFSH/r-hLH (Pergoveris) for 0.5 µg of r-hFSH (GONAL-f^®, Merck KGaA) and the buserelin acetate was injected 1 d after the hormonal treatment finished. Female guinea pigs were exposed to males for four days after the superovulation treatment finished. To ensure that females were mated, males were changed each 12 h. Females were slaughtered at Day 4 after the treatment finished, and embryos were collected by flushing the oviduct and uterus with Ringer’s lactate solution with polyvinyl alcohol. The data were analysed using one-way analysis of variance, where the weight of females was included as covariance. RStudio v. 4.1.0 was used to perform the analysis. Treatments were not statistically different for the superstimulation response or number of embryos recovered. 100% of females treated in each group ovulated and all of them only produced embryos. However, 50% (3/6) of guinea pigs treated in Group 1 responded to superstimulation treatment versus 71% (5/7) of Group 2. The number of embryos recovered for these females were over the average ovulation rate and litter size in this species (range between 2.8 to 3.5). This study reached 5.8 ± 2.05 and 8.57 ± 1.90 embryos recovered for Group 1 and 2, respectively. The embryos recovered were classified as embryo with two, four, and eight cells, and morula. This study is the first where recombinant human gonadotrophin hormones were used in guinea pigs. The results indicate that both hormonal treatments, r-hFSH/r-hLH or only r-hFSH, are useful for inducing ovarian superstimulation in guinea pigs within a short superovulation protocol.