Control of new follicular wave emergence and rate of follicular maturation in bos indicus-influenced cattle with estradiol benzoate, temporary calf removal and progesterone

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Title: Control of new follicular wave emergence and rate of follicular maturation in bos indicus-influenced cattle with estradiol benzoate, temporary calf removal and progesterone
Author: Pack, Julie Diane
Abstract: Objectives were to determine : 1 ) whether estradiol benzoate (EB ) provides a superior alternative to GnRH for synchronizing emergence , growth and maturation of a new follicular wave for fixed timed AI (TAI ) in Bos indicus -influenced cattle using CIDR -based protocols , 2 ) the effect of 48 h calf removal at CIDR removal on the rate of maturational synchrony of the dominant follicle and 3 ) the effect of varying the magnitude of peak plasma progesterone (P4 ) concentrations following CIDR insertion on the suppression of FSH and LH secretion in a CIDR -based protocol using EB . In experiment 1 , sixty -four Braford (F -1 ) females were stratified by BCS , parity and days postpartum and assigned randomly to one of four groups in a 2 x 2 factorial arrangement of treatments : 1 ) Select -Synch + CIDR , 2 ) Select -Synch + CIDR with 48 h calf removal , 3 ) E -Synch + CIDR or 4 ) E -Synch + CIDR with 48 h calf removal . A greater number of cattle in the EB treated group exhibited NFWE compared to the GnRH group , 29 vs 17 cows for EB and GnRH respectively , (P <0 .0006 ) . Intervals to NFWE were also greater in EB treated cattle than in GnRH treated cattle , 4 .2 vs 2 .7 d for EB and GnRH treated cattle respectively , (P <0 .0001 ) . Proportions of GnRH - and EB -treated cows ovulating after CIDR removal did not differ . Post -CIDR suckling status did not affect ovulation frequency or interval to ovulation . In experiment 2 , eight pubertal (F -1 ) heifers were used in a Latin Square design with four treatment levels of P4 : 1 ) EB only , 2 ) EB and new CIDR , 3 ) EB and new autoclaved CIDR , 4 ) EB , new autoclaved CIDR and P4 injection at CIDR insertion . Treatments 2 through 4 increased (P < 0 .01 ) mean plasma P4 concentrations compared to treatment 1 , with treatment 4 creating the greatest increase in P4 with the longest duration . Suppression of plasma FSH was greatest in group 4 (P <0 .08 ) , with mean 60 h concentrations less than in all other groups . Mean concentrations of LH were lesser in group 4 than groups 1 and 2 . Frequencies of occurrence of NFWE and ovulation and intervals to NFWE did not differ among treatments . Results indicate that the use of EB and CIDR to synchronize Brahman x Hereford females may provide better synchronization for TAI compared to GnRH and CIDR based protocols .
URI: http : / /hdl .handle .net /1969 .1 /ETD -TAMU -2367
Date: 2009-05-15

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Control of new follicular wave emergence and rate of follicular maturation in bos indicus-influenced cattle with estradiol benzoate, temporary calf removal and progesterone. Available electronically from http : / /hdl .handle .net /1969 .1 /ETD -TAMU -2367 .

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