Resumen

ARMENDANO, J.I. et al. Efecto de la sal de estradiol, estatus ovárico y condición corporal sobre el porcentaje de preñez en vacas con cría IATF. Rev. vet. [online]. 2015, vol.26, n.2, pp.108-112. ISSN 1669-6840.

An experiment was carried out with the aim of evaluate the effect of estradiol cypionate (ECP) given at intravaginal progesterone-releasing device (DISP) removal on the FTAI pregnancy rate (PR) in suckled beef cows, as well as to evaluate the association between body condition score (BCS) and the ovarian status (OS) at the beginning of the synchronization protocol and its relationship with the PR. Ninety-one suckled Aberdeen Angus (AA) and Polled Hereford (PH) cows with a 50 to 80 postpartum interval days were used. On day 0 BCS was estimated and the OS was determined by ultrasonography as corpus luteum (CL), follicle ≥10 mm (F≥10), or <10 mm (F<10), and a 0.5 g DISP was inserted with an injection of 2 mg of estradiol benzoate (EB). On day 8 DISPs were removed, 0.5 mg of DL-cloprostenol were injected and animals were randomly divided in two groups, considering the OS, to receive 1 mg of ECP in this moment or 1 mg of EB 24 h later. For the FTAI (53-54 h post-removal), semen of two bulls of proven fertility were used. The ultrasonographic pregnancy diagnosis was performed 49 days post-FTAI. An association between BCS and OS was found, being different the proportion of F<10 and F≥10 (BCS4: F<10= 66.7%-10/15-, F≥10= 26.7%-4/15-; BCS5-7:F<10= 24.0%-18/75-, F≥10 = 60.0%-45/75-; p<0.05), without differences on CL proportions (BCS4= 6.7%-1/15-; BCS5-7= 16.0%-12/75-; p>0.05). The PR was affected by breed/bull (AA= 48.6%-36/74-; PH= 18.7%-3/16-; p<0.05) and by the OS, being higher when a CL was present (F<10= 35.7%-10/28; F≥10= 38.8%-19/49-; CL= 76.9%-10/13-; p<0.05). There was not effect of the estradiol salt used (EB= 45.4%-20/44-; ECP= 41.3%-19/46-; p>0.05), of the BCS (BCS4= 26.7%-4/15-; BCS5-7= 46.7%-35/75-; p>0.05), or the interaction. In conclusion, the use of ECP at the moment of DISP withdrawal has no influence on the fertility of suckled beef cows at FTAI, the BCS influences the OS, and the OS affects the PR in anestrous animals

Palabras clave : cow; postpartum anestrous; body condition score; ovarian status; estradiol cypionate.

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