Reuse of norgestomet implants in an eCG-based superovulation protocol administered to Nelore (Bos taurus indicus) cows

Abstract

This study assessed the reuse of norgestomet implants in Nelore cows that were superstimulated with eCG. In a crossover design trial, eight cows were randomly divided into two experimental groups and twice superstimulated: Group 1half of the cows received a new norgestomet implant and 2 mg estradiol benzoate (EB) on Day 0; Group 2remaining cows received two once-used norgestomet implants and 2 mg EB also on Day 0. On Day 4 all cows received a single dose of 2000 IU eCG, and on Day 6 cows were treated with two doses of PGF 2α 12 h apart. Ovulation was induced with 12.5 mg pLH 12 h after implant withdrawal (on Day 7), and fixedtime artificial inseminations were carried out 12 and 24 h later. Seven days after pLH injection embryos were recovered and blood samples were taken to determine circulating progesterone. Ultrasound examinations were performed at pLH administration and at embryo recovery. The number of large follicles (≥8 mm) was greater (Pb 0.05) in Group 1 (17.1 ± 1.8) than in Group 2 cows (9.7± 1.6). The mean number of corpora lutea was greater (Pb 0.05) for Group 1 (13.8 ± 1.8) as compared to Group 2 cows (5.4± 1.0) and the percentage of large follicles that ovulated following pLH administration also differed (Pb 0.05) between treatments (80.3% and 53.8% for cows in Groups 1 and 2, respectively). However, no differences (PN 0.05) were found between treatments (respectively, for Group 1 and Group 2 cows) in the follicle diameter (10.5 ± 1.6 and 10.2± 1.7 mm), corpus luteum (CL) diameter (15.7 ± 1.8 and 14.4± 1.7 mm), CL volume (2232 ± 1356 and 1893± 1828 mm 3), ova/embryos recovered (6.3± 1.1 and 4.0 ± 1.9), transferable embryos (4.0± 1.8 and 2.5 ± 1.0) and plasma progesterone concentration (36.1 ± 8.3 and 35.1± 6.9 ng/mL). In conclusion, the stimulatory effects on the ovaries provided by the use of two onceused implants were less intense than the ones verified after using a new implant.

Forskolin effect on the cryosurvival ofin vitro-produced bovine embryos in the presence or absence of fetal calf serum

“…Forty-five blastocysts were collected 7 days after the first artificial insemination using a 22G Foley probe and retrieved in a 75-μm plastic filter (Sudano et al ., 2011a). The schemes for the induction of superovulation and embryo collection are shown in Fig.…”

Respuesta ovárica y embrionaria de dos protocolos de superovulación en bovinos altoandinos Pardo Suizo

“…La evaluación ecográfica de los ovarios en ambos protocolos se realizó el día de la administración de los inductores de ovulación, para el conteo y medición de los folículos pre ovulatorios (FPO); y el día del flushing, para el conteo y medición de los cuerpos lúteos (CLs) (Figura 1), para lo cual se utilizó un equipo ecográfico MyLab™One con transductor linear de 7,5MHz. El conteo de los folículos y la posterior presencia de CLs permitió estimar la tasa de ovulación (Sudano et al, 2011).…”

“…En la actualidad la SOV ha presentado resultados muy variables en cuanto a la respuesta ovárica, desarrollo y calidad embrionaria, lo cual representa una gran dificultad para la implementación de OMTE en bovinos (González et al, 2001). Diversos estudios han realizado múltiples protocolos hormonales con el objetivo de mejorar los resultados de la SOV, y eludir la variabilidad de los resultados; sin embargo, las mejoras son pocas (Sudano et al, 2011).…”

“…El uso de la eCG en bovinos lecheros demostró que es capaz de inducir el reclutamiento de un mayor número de folículos antrales, de estimular una mayor tasa de crecimiento folicular, dando origen a un folículo preovulatorio mejor desarrollado; y el CL formado a partir de esos folículos es una estructura altamente funcional (Baruselli et al, 2010;Păcală et al, 2010;De Rensis & López-Gatius, 2014). Otra ventaja de la eCG es su administración en dosis única (de entre 1500 a 3000 UI/animal), suficiente para estimular el crecimiento de los folículos (Murphy & Martinuk 1991;Bó & Mapletoft 2018); asimismo el uso de eCG puede actuar de forma semejante a la FSH y LH, lo que podría ayudar a reducir los costos de la SOV bovina (Sudano et al, 2011).…”

A reutilização de um implante de Norgestomet na manifestação de estro ovino

“…Ainda, vários experimentos principalmente nas espécies bovina e caprina revelam que a reutilização do dispositivo auricular permite alcançar níveis satisfatórios de estro e prenhez, inclusive, em programas de superovulação proporcionando uma vantajosa relação entre o custo e benefício (Almeida et al, 2006;Sudano et al, 2011;Mellado & Valdez, 1997). Sendo assim, o objetivo deste trabalho experimental foi o de avaliar o desempenho do implante auricular a base de Norgestomet de primeiro uso e previamente reutilizado na incidência de estro de borregas da raça Texel associado ao eCG e a um análogo de prostaglandina.…”