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Ovarian follicular dynamics and fertility to AI or ET after estradiol or estradiol and progesterone administration in combination with a controlled internal drug release insert
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Three experiments were designed to determine the effects of estradiol or estradiol and progesterone administration in combination with a controlled internal drug release (CIDR) insert at treatment initiation or after CIDR removal on follicular dynamics and estrous and fertility rates. Experiments were conducted over a period of two years and included Bos indicus and Bos taurus cattle. Each female received a CIDR for 7 or 8 d with prostaglandin F₂[a] (25 mg, im) upon removal. The first experiment determined effects of estradiol benzoate (EB) administration either 24 h post-CIDR removal or EB administration upon CIDR insertion on estrus and fertility rates to artificial insemination (AI) or embryo transfer (ET). EB administration 24 h post-CIDR removal consistently increased estrus and fertility rates to AI and ET regardless of parity, lactational state, and post-partum interval. EB administration upon CIDR insertion did not affect first service conception rates to AI or ET. However, parity and post-partum interval did affect first service conception rates in those trials. In addition, there was an affect of duration of CIDR administration (7- or 8-d) on estrus and fertility rates in nulliparous, Bos indicus-influenced females. The second experiment determined the effects of EB or EB and progesterone (EB + P4) administration at CIDR insertion on follicular dynamics and mean serum P4 concentrations. Mean serum P4 concentrations were affected by an interaction between follicle diameter (mm) and treatment. Mean dominant follicle diameter (mm) was influenced by treatment and breed type. The third experiment determined the effects of estradiol 17b (E-17β) or E-17β and progesterone (E-17β + P4) at time of CIDR insertion on first service conception rates to timed insemination. There was no significant difference between treatments at CIDR insertion on first service conception rate. However, post-partum interval, location of trial, and technician did affect first service conception rate. These results indicate that EB administration 24 h post-CIDR removal consistently and significantly increased synchrony rates. In addition, late post-partum and multiparous females had higher overall first service conception rates to either AI or ET than did females in which the post-partum interval was less than 75 d or parity was less than two progeny respectively. Timed insemination proved successful in field trials with first service conception rates ranging from 55.3 to 65.0% among the five locations.
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Includes bibliographical references (leaves 67-75).
Issued also on microfiche from Lange Micrographics.
Meyer, Jonalee Ann (2000). Ovarian follicular dynamics and fertility to AI or ET after estradiol or estradiol and progesterone administration in combination with a controlled internal drug release insert. Master's thesis, Texas A&M University. Available electronically from
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