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Anim. Reprod.; 8(1/2): 9-13, 2011. tab

Artigo em Inglês | VETINDEX | ID: vti-8568

Resumo

The objective of this study was to determine if exposure of 2 - y ea r - old beef heifers to androgenized steers (AS) for 30 days before the beginning of an estrous synchronization protocol (ESP) and artificial insemination ( AI ) increases the estrous response and pregnancy rate . Hereford x Braford heifers were stratified by body weight and presence of a corpus luteum (CL) and assigned to be 1) e xposed to AS ( EAS ; n = 53) or 2) n o t exposed to AS ( NE ; n = 53) for 30 d ays (D ay 0 = first d ay of exposure) . Proportion s of heifers with a CL on D ay - 7 were 20.6 and 24.5% for EAS and NE , respectively. Ovaries of each heifer were scanned on Days 15 and 30 of the exposure period for a CL . On D ay 30, steers were removed from the EAS heifers and t wo doses of a PG F 2alpha analogue were administered to each heifer 11 d ays apart . Heifers were observed for behavioral estrus for 6 d ys , beginning 48 h after the last PGF 2alph a injection , and inseminated 12 h after estrus detection . More EAS than NE heifers had a CL on D ay 15 ( 5 4.7 and 32.1%, EAS and NE, respectively; P < 0.02) , but there was no difference in the proportion of heifers that had a CL by D ay 30 ( 73.6 and 72 .0 % , EA S and NE, respectively; P = 0.2 ) . There were no difference s between EAS and NE heifers for proportion s that showed estrus ( 66.0 and 67.9 % , EAS and NE, respectively ; P = 0. 8 ), conception rates ( 83 . 0 and 92 . 0 %, EAS and NE, respectively; P = 0. 3 ) and pregnancy rates ( 83 . 0 and 86.5 %, EAS and NE, respectively; P = 0. 6 ) . Exposing 2 - y ea r - old heifers to AS under the conditions of this experiment before an ESP that included a double injection of PGF 2alpha had no effects on estrous response and AI pregnancy rates.(AU)

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Localização: BR68.1