196 Embryo production using follicle-stimulating hormone (FSH) or FSH+equine chorionic gonadotropin in beef donors

Abstract

The objective of the present study was to evaluate the superovulatory response and embryo production in beef donors using 8 twice-daily injections of FSH or an alternative protocol in which the last 4 FSH injections were replaced with a single injection of eCG. In Exp. 1, 12 mature Bonsmara donor cows, with a body condition score between 3 and 4 (1 to 5 scale) were superstimulated twice every 46 days in a crossover design (i.e. in each experiment all cows received 2 treatments and the 2 treatments were equally represented in each replicate). On Day 0 a.m., all donors received an intravaginal device with 1.2g of progesterone (Diprogest 1200®, Zoovet, Santa Fe, Argentina), along with 50mg of progesterone i.m (Progestar®, Zoetis, Buenos Aires, Argentina) and 5mg of oestradiol-17β (17βOestradiol®, Rio de Janeiro, Argentina) IM. On Day 4 a.m., the superstimulatory treatments were initiated and donors in the control group received 8 applications of FSH (Folltropin-V, Vetoquinol, Lure, France), IM (total dose: 300mg NIH-FSH-P1) in a twice-daily decreasing dosage schedule over 4 days (i.e. 60, 60, 50, 50, 30, 30, 10, and 10mg, respectively). Donors in the FSH+800 eCG group received only the first 4 applications of FSH (i.e. 60, 60, 50 and 50mg, respectively) and on Day 6 a.m. they received 800IU of eCG (Novormón®, Zoetis) IM in a single dose. All donors received 500μg of cloprostenol (Ciclase DL®, Zoetis) IM on Day 6 a.m. and p.m., and the intravaginal devices were removed on Day 7 a.m. All cows also received 100μg of gonadorelin acetate (GnRH, Gonasyn gdr, Zoetis) on Day 8 a.m. and were inseminated with frozen-thawed semen from 2 bulls 12 and 24h later. On Day 15, ova/embryos were collected and evaluated according to the IETS standards. The data were analysed by GLMM (Infostat, 2018). In Exp 2., 18 Bonsmara donors with similar conditions as those in Exp. 1 were superovulated twice in a crossover design. Cows in both groups received similar treatments to those in the FSH+eCG treatment of Exp. 1, except that the total dosage of FSH was 200mg (i.e. 60, 60, 40, and 40mg, respectively) and the eCG given on Day 6 a.m. was either 600IU (group 1) or 800IU (group 2). In Exp 1., the FSH (control) group had a higher (P<0.01) number of fertilized oocytes, but there were no differences in the other end points evaluated (Table 1). In Exp. 2, no differences were found between FSH+800 eCG and FSH+600 eCG groups in any of the parameters evaluated. In conclusion, the replacement of the last 4 injections of FSH by a single dose of eCG decreases the number of treatments required in a superovulation program without negatively affecting the production of transferable embryos. Table 1.Embryo production (means±s.e.m.) in Bonsmara donors treated with FSH or FSH+eCG

Strategies to increment in vivo and in vitro embryo production and transfer in cattle

“…Although the administration of eCG near the end of the FSH treatment protocol did not always improve the superovulatory response, it was not detrimental and raised some interest in its use to simplify the superstimulation protocol and to decrease the cost of the treatment, since eCG is usually less expensive than the pituitary extracts containing FSH. Therefore, we designed a study to evaluate the superovulatory response and embryo production in beef donors using twice daily FSH injections over 4 days or an alternative protocol in which the last 4 FSH treatments were replaced by a single injection of eCG (Barajas et al, 2019). Twelve (Experiment 1) and 18 (Experiment 2) mature Bonsmara donor cows were superstimulated twice at a 46-day interval in a crossover design.…”

Evaluación de un protocolo simplificado de superovulación en vacas Holstein en producción con semen sexado y convencional

“…El objetivo de este trabajo fue validar un protocolo simplificado de superovulación en vacas Holstein en producción ya que ha sido probado en vacas Bonsmara (Barajas et al, 2019) y mestizas Bos taurus x Bos indicus (Chacón et al, 2020). Los resultados de este y los dos trabajos citados anteriormente coinciden, el reemplazo de las cuatro últimas dosis de FSHp por 600UI de eCG resulta en una respuesta superovulatoria y un número de embriones transferibles similares al protocolo convencional.…”

“…La aplicación de los tratamientos superovulatorios en vacas resulta dificultosa ya que se debe inyectar a las donantes dos veces por día durante cuatro días, lo que causa estrés en el animal y aumenta el costo debido a la mano de obra y movilización de los animales. Recientemente, se demostró que reemplazar las cuatro últimas dosis de FSHp por una dosis de eCG produce una respuesta superovulatoria y número de embriones similar al protocolo convencional, simplificando así el tratamiento (Barajas et al, 2019). El objetivo de este trabajo fue evaluar la aplicación de un tratamiento superovulatorio simplificado en vacas Holstein en producción, reemplazando las 4 últimas dosis de FSHp con una dosis de eCG con el uso de semen sexado y convencional sobre la respuesta superovulatoria y estructuras recuperadas.…”