Progesterone concentrations, exogenous equine chorionic gonadotropin, and timing of prostaglandin F-2 alpha treatment affect fertility in postpuberal Nelore heifers


Autoria(s): Dias, C. C.; Wechsler, Francisco Stefano; Day, M. L.; Vasconcelos, José Luiz Moraes
Contribuinte(s)

Universidade Estadual Paulista (UNESP)

Data(s)

30/09/2013

20/05/2014

30/09/2013

20/05/2014

01/08/2009

Resumo

Two experiments were performed to test the hypothesis that elevated progesterone concentrations impair pregnancy rate to timed artificial insemination (TAI) in postpuberal Nelore heifers. In Experiment 1, postpuberal Nelore heifers (n = 398) received 2 mg estradiol benzoate (EB) and either a new progesterone-releasing intravaginal device containing 1.9 g of progesterone (CIDR) (first use) or a CIDR previously used for 9 d (second use) or for 18 d (third use) on Day 0, 12.5 mg prostaglandin F-2 alpha (PGF(2 alpha)) on Day 7, 0.5 mg estradiol cypionate (ECP) and CIDR withdrawal on Day 9, and TAI on Day 11. Largest ovarian follicle diameter was determined on Day 11. The third-use CIDR treatment increased largest ovarian follicle diameter and pregnancy rate. Conception to TAI was reduced in heifers with smaller follicles in the first- and second-use CIDR treatments, but not in the third-use CID treatment. In Experiment 2, postpuberal Nelore heifers received the synchronization treatment described in Experiment 1 or received 12.5 mg PGF2. on Day 9 rather than Day 7. In addition, 50% of heifers received 300 IU equine chorionic gonadotropin (eCG) on Day 9. Heifers were either TAI (Experiment 2a; n = 199) or Al after detection of estrus (Experiment 2b; n = 125 of 202). In Experiment 2a, treatment with cCG increased pregnancy rate to TAI in heifers that received PGF2. on Day 9 but not on Day 7 and in heifers that received a first-use CIDR but not in heifers that received a third-use CIDR. Treatments did not influence reproductive performance in Experiment 2b. In summary, pregnancy rate to TAI in postpuberal Nelore heifers was optimized when lower concentrations of cxogcnous progesterone were administered, and eCG treatment was beneficial in heifers expected to have greater progesterone concentrations. (C) 2009 Elsevier B.V. All rights reserved.

Formato

378-385

Identificador

http://dx.doi.org/10.1016/j.theriogenology.2009.03.006

Theriogenology. New York: Elsevier B.V., v. 72, n. 3, p. 378-385, 2009.

0093-691X

http://hdl.handle.net/11449/14307

10.1016/j.theriogenology.2009.03.006

WOS:000268216300010

Idioma(s)

eng

Publicador

Elsevier B.V.

Relação

Theriogenology

Direitos

closedAccess

Palavras-Chave #Cattle #Pregnancy #Proestrus #Progesterone #Timed artificial insemination
Tipo

info:eu-repo/semantics/article