[Function of the corpus luteum developed from the ovulation of a persistent dominant follicle in Holstein heifers treated with a controlled internal drug release-bovine device (CIDR-B) in absence of a corpus luteum] | Funcion del cuerpo luteo formado a partir de la ovulacion de un foliculo dominante persistente, en vaquillas Holstein tratadas con un dispositivo intravaginal de liberacion de progesterona (CIDR-B) en ausencia de un cuerpo luteo

Inglés. The objective of this study was to evaluate the corpus luteum function developed from the ovulation of a persistent dominant follicle in Holstein heifers pretreated with a controlled internar drug release-bovine device (CIDR-B) in the absence of a corpus luteum. Twenty four heifers were treated with 25 mg of prostaglandin F2alpha (PGF2alpha) intramuscularly (im). Eleven days later, twelve of these heifers were fitted with a CIDR-B (Group l; CIDR-B plus corpus luteum). The rest of the heifers (n= 12) were fitted with a CIDRB and received 25 mg PGF2alpha lm (Group 2; CIDR-B, without corpus luteum). In both groups the CIDR-B was fitted without estrogens and remained in place for 12 days. Follicular development was assessed by transrectal ultrasonography. Two heifers from Group 1 (16.6%) and 8 from Group 2 (66.6%; PO.05) presentes a persistent dominant follicle which ovulated upon removal of the intravaginal device. In the other heifers a different follicle ovulated. Blood samples were collected daily to measure the concentrations of progesterone on 7 animals from Group 1 that ovulated a different follicle, and 7 from Group 2 that ovulated a persistent dominant one. Sampling started on day 1 (day of standing estrus), and continued until day 16. There were no differences (PO.05) in progesterone concentrations between groups. It is concluded that there was no evidence that the corpus luteum, which developed from the ovulation of a persistent dominant follicle in heifers treated with a CIDR-B and in absence of a corpus luteum, has an impaired function

Español; castellano. Se evaluo la funcion del cuerpo luteo (CL) formado a partir de la ovulacion de un foliculo dominante persistente, en vaquillas Holstein tratadas con un dispositivo intravaginal de liberacion de progesterona (CIDR-B), en ausencia de un CL. Veinticuatro vaquillas recibieron 25 mg de prostaglandina F2alpha (PGF2alpha) im. Once dias despues a las vaquillas del grupo 1 (n= 12) se les inserto un CIDR-B (CIDR-B con CL), a las vaquillas del grupo 2 (n= 12) se les inserto un CIDR-B y recibieron 25 mg de PGF2alpha im (CIDR-B sin CL). En ambos grupos el CIDR-B se inserto sin estradiol y permanecio 12 dias. Se evaluo el desarrollo folicular mediante ultrasonografia. En 2 vaquillas (16.6%) del grupo 1 y en 8 del grupo 2 (66.6%; P0.05) el foliculo dominante observado el dia de la insercion del CIDR-B persistio y ovulo despues del tratamiento; en los animales restantes ovulo un foliculo diferente. Se obtuvieron muestras sanguineas para la determinacion de progesterona diariamente, a partir del dia del estro (dia l) hasta el dia 16 del ciclo de 7 vaquillas del grupo 1, en las cuales ovulo el foliculo diferente, y de 7 vaquillas del grupo 2, en las que ovulo un foliculo dominante persistente. Las concentraciones de progesterona fueron similares en las vaquillas de ambos grupos (P0.05). En el presente trabajo no se encontro evidencia de que el cuerpo luteo que se desarrolla a partir de la ovulacion de un foliculo dominante persistente en vaquillas tratadas con un CIDR-B en ausencia de un cuerpo luteo, tenga afectada su funcion