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Effects of differential ewe body condition at mating and early post-mating nutrition on embryo survivalWest, Kathryn S. 16 April 1990 (has links)
Two trials were conducted over consecutive years to examine the effects of ewe
body condition and post-mating nutrition on ovulation rates and embryo survival. Trial 1
used 146 Polypay ewes ranging in age from 5 to 8 years in a 3 x 2 factorial array of pre-mating
(high-H, low flushed-LF and low unflushed-L) and post-mating nutrition (high and
low) treatments. Trial 2 was a 2 x 2 x 2 factorial array of 60 Polypay and 60 Coopworth x
Polypay (C x P) three year old ewes, two pre-mating (H and LF) and two post-mating
(high and low) treatments. To estimate timing and extent of embryo loss, two methods of
embryo detection were employed during Trial 2. Real-time ultrasound was performed on
all ewes at 21, 28, 34 and 45 days post-mating. Blood samples were also collected on
these days for analysis of Pregnancy-specific Protein B (PSPB) levels. There was no
effect of pre-mating treatment or ewe age on ovulation or conception rates for Trial 1. Pre-mating
treatment was significant in Trial 2, with H ewes having higher ovulation rates than
LF ewes. Pre-mating treatment, post-mating treatment, ewe age (for Trial 1) and genotype
(for Trial 2) had no effect on mean litter size in either trial. Analysis of litter size among
ewes with twin and triple ovulations showed pre-mating treatment to be significant among
triple ovulators in Trial 1, where L ewes had much lower litter size (1.86) than LF (2.37)
or H (2.60) ewes. In Trial 2, post-mating treatment was significant among the ewes with
triple ovulations, with ewes on low nutrition having lower litter size (2.01) than ewes on
high nutrition (2.59). Two-way interactions were significant among twin and triple
ovulators in Trial 2. Breed x pre-mating interaction among twin ovulating ewes showed C
x P LF ewes to have lower litter size (1.43) than the H ewes (1.87), while the opposite was
true for Polypay ewes. Pre- x post-mating treatment interaction among triple ovulators
showed LF ewes on low post-mating nutrition had lower mean litter size. This effect is
largely due to lower litter size in the C x P triple ovulators on low post-mating nutrition.
Data available from the ultrasound diagnosis showed little indication of treatment effects on
amount or time of embryo loss. Ewes bearing single or multiple embryos differed in PSPB
level at day 45, but not at earlier times. However, there were no differences in PSPB
levels in ewes with twin or triple embryos at any of the trial days. Assay for PSPB failed
to facilitate detection of the amount or time of embryo loss, as determined by ultrasound. / Graduation date: 1991
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Corpus luteum function in hysterectomized and unilaterally hysterectomized ewes treated with gonadotropin-releasing hormoneWhitmore, Diana L. 13 March 1995 (has links)
Graduation date: 1995
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A study of factors affecting embryonic, fetal and lamb survival in high fecundity merino ewesKleemann, D. O. January 1994 (has links) (PDF)
Bibliography : leaves 120-133. Defines the sources of reproductive wastage in FecB FecÊ Booroola Merino x South Australian Merino ewes and examines factors associated with the survival of embryos, fetuses and lambs with the aim of improving net reproduction efficiency. Experiments were conducted to define the problem; to examine factors affecting embryonic and fetal loss; and, to investigate factors influencing wastage at lambing.
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Endocrine correlates of fecundity in the eweRalph, Meredith Margaret. January 1984 (has links) (PDF)
Bibliography: leaves 182-210.
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Endocrine correlates of fecundity in the ewe / by Meredith Margaret RalphRalph, Meredith Margaret January 1984 (has links)
Bibliography: leaves 182-210 / vii, 210 leaves : ill ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.)--Dept. of Obstetrics and Gynaecology, University of Adelaide, 1985
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