xv, 225 leaves : / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (M.D.)--University of Adelaide, Dept. of Medicine, 1979

xv, 225 leaves : / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (M.D.)--University of Adelaide, Dept. of Medicine, 1979

Thesis (M.D.)--University of Adelaide, Dept. of Medicine, 1979.

Thesis (Ph. D.)--University of Wisconsin--Madison, 1969. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliography.

Thesis (Ph.D.) -- University of Adelaide, Department of Obstetrics and Gynaecology, 1981.

A series of studies were guided by the principal hypothesis that it was necessary to characterize ovarian function during the seasons of the annual reproductive cycle in wapiti and that from this knowledge novel methods of exogenous control of ovarian function would be possible. To augment existing knowledge about endogenous control of ovarian function in wapiti studies were conducted to characterize ovarian follicle dynamics during the estrous season and to characterize ovarian follicular dynamics during the periods of transition into and out of the breeding season. The third study was designed to characterize ovarian follicle development and ovulation synchrony subsequent to an estrous synchronization protocol used commercially. To evaluate novel methods of exogenous control of ovarian function studies were conducted to determine if follicular wave emergence could be electively induced using hormonal or surgical treatments to evaluate novel ovarian superstimulatory treatment protocols. <p>It was concluded from the studies of ovarian function that follicle development during the breeding season was characterized by the regular and synchronous development of follicular waves and that 2, 3, or 4 waves occurred during each interovulatory interval. Transition into the breeding season was preceded by one short interovulatory interval (9 days) characterized by one wave of follicle development and a small, short-lived and hypo-functional corpus luteum. The last estrous cycle of the breeding season was similar to estrous cycles during the rut (21 days), but and transition to anestrus was marked by a failure of the dominant follicle to ovulate after luteal regression. The treatment protocol used commercially for estrous synchronization was effective, but unnecessarily long. It was concluded from the studies on exogenous control of ovarian function that follicular wave emergence could be electively induced using steroid hormones or follicle ablation and may be useful for estrus synchronization and superstimulatory protocols. The tested superstimulatory treatments were effective and had the advantage of reducing the treatment period by 6 days and the number of times the animals are handled by one third over a more conventional method. However, oocyte and embryo quality were not evaluated. <p>As a result of the studies conducted and one previous study during the anouvlatory season follicle and luteal dynamics are now known in wapiti for all seasons of the year and this knowledge will provide a template upon which other species of deer can be compared. The final two studies support the principal hypothesis. The novel methods of exogenous ovarian control tested increase the potential for success when applying reproductive technologies and the successful application of these methods in wapiti should lead to their successful use in other species of deer.

A series of studies were guided by the principal hypothesis that it was necessary to characterize ovarian function during the seasons of the annual reproductive cycle in wapiti and that from this knowledge novel methods of exogenous control of ovarian function would be possible. To augment existing knowledge about endogenous control of ovarian function in wapiti studies were conducted to characterize ovarian follicle dynamics during the estrous season and to characterize ovarian follicular dynamics during the periods of transition into and out of the breeding season. The third study was designed to characterize ovarian follicle development and ovulation synchrony subsequent to an estrous synchronization protocol used commercially. To evaluate novel methods of exogenous control of ovarian function studies were conducted to determine if follicular wave emergence could be electively induced using hormonal or surgical treatments to evaluate novel ovarian superstimulatory treatment protocols. <p>It was concluded from the studies of ovarian function that follicle development during the breeding season was characterized by the regular and synchronous development of follicular waves and that 2, 3, or 4 waves occurred during each interovulatory interval. Transition into the breeding season was preceded by one short interovulatory interval (9 days) characterized by one wave of follicle development and a small, short-lived and hypo-functional corpus luteum. The last estrous cycle of the breeding season was similar to estrous cycles during the rut (21 days), but and transition to anestrus was marked by a failure of the dominant follicle to ovulate after luteal regression. The treatment protocol used commercially for estrous synchronization was effective, but unnecessarily long. It was concluded from the studies on exogenous control of ovarian function that follicular wave emergence could be electively induced using steroid hormones or follicle ablation and may be useful for estrus synchronization and superstimulatory protocols. The tested superstimulatory treatments were effective and had the advantage of reducing the treatment period by 6 days and the number of times the animals are handled by one third over a more conventional method. However, oocyte and embryo quality were not evaluated. <p>As a result of the studies conducted and one previous study during the anouvlatory season follicle and luteal dynamics are now known in wapiti for all seasons of the year and this knowledge will provide a template upon which other species of deer can be compared. The final two studies support the principal hypothesis. The novel methods of exogenous ovarian control tested increase the potential for success when applying reproductive technologies and the successful application of these methods in wapiti should lead to their successful use in other species of deer.

Thesis (M.S.)--University of Wisconsin--Madison, 1983. / Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 81-94).

Selective breeding of chickens for high growth rate and other production traits has led to the modern commercial broiler, a bird that has the genetic potential for reaching an average body weight of 2.7kg within 6 weeks of hatch. However, the breeding stock for modern broilers has to be feed controlled in order to lay large numbers of viable hatching eggs. Broiler breeders, when fed ad libitum, have a propensity to produce internal ovulations, double-yolked, misshapen or shell-less eggs. This is due to the release of multiple ova at ovulation, which results in a significant loss of production. Feed control has been shown to mitigate this effect but welfare concerns have been raised as to the side-effects for the birds. The main objective of this research was to determine the genetic basis for the regulation of ovarian follicle selection and its dysfunction in ad libitum-fed broiler breeders, and how this might be addressed by genetic selection to limit the impact on the management and welfare of future broiler breeders. A multi-layered statistical, expression profiling and cluster analysis of ovarian gene expression data from a microarray study was carried out to identify candidate genes for further study.Key stages of development were investigated for feed restricted and ad libitum-fed broiler breeders. Several gene candidate genes were validated by qPCR in a comparison of different ovarian tissues in layer type hens for subsequent analysis in broiler breeders. Sequencing of the founders of an Advanced Intercross Line (AIL) of commercial broiler breeders and White Leghorn layers was performed covering 3 regions of each of the primary candidate genes in order to identify genetic variation that could account for differences in follicle number between broilers and layers. Expression data from a microarray study highlighted a number of potential candidate genes for regulation of follicle development. One of these genes, Platelet Derived Growth Factor Receptor Like (PDGFRL), shares significant sequence homology with the active domains of Platelet Derived Growth Factor Receptor β. Expression profiling in layers showed peak PDGFRL expression in 5-6 mm follicles and the F2 follicle (P <0.001). PDGFRL was also up-regulated in response to ad libitum feeding in broiler breeders in 6-8 mm follicles (P<0.016), the point at which follicle selection and recruitment is considered to occur. In addition to this, while PDGFRL expression remains relatively constant between tissues under ad libitum conditions, it shows a clear reduction in expression (P <0.001) in prehierarchical follicles relative to the stroma and the F1 follicle under feed restriction. This observation is consistent with results from the original microarray study. Sequencing of the AIL Founders highlighted several SNPs in the broiler that have the potential to be used as markers for incorporation into commercial selection programs. EST alignment in preparation for targeted sequencing of PDGFRL also highlighted three potential forms of the protein, each with a different 5’ starting sequence. Initial investigation has shown all three to be expressed in ovarian follicles. QPCR in a panel of 13 tissues shows marked differences between the 3 variants, implying different and perhaps specialised roles for each. The PDGFR family has a potential role in steroidogenesis, and the expression profiling, combined with the clear effect on expression from ad libitum feeding in broiler breeders, suggest that PDGFRL is a strong candidate for involvement in the regulation of follicle development GDF9, shown to be associated with multiple ovulation in sheep, and FSH receptor, a mediator of neuroendocrine signalling to the ovary, were also investigated. They behaved as expected in layer type birds but both showed significant differential expression (P = 0.005 and 0.018 respectively) as a result of ad libitum feeding in broiler breeders. Though these two genes have been extensively investigated, these are previously unobserved effects. SNPs have also been identified in these genes which have the potential to be used as markers for incorporation into commercial selection programs. To fully exploit these results, additional investigation is recommended to confirm these results in commercial populations and to determine how they can be employed to best effect.

The main themes of the present thesis was the regulation of ovarian antral follicle growth, the manipulation of follicular dynamics and ovulation rate, as well as the characterization of the ovine corpus luteum (CL). Two treatments with ovine follicle stimulating hormone (oFSH) were used to assess the responsiveness of small antral follicles during different times in a follicular wave. Follicular dynamics were monitored by transrectal ultrasonography and serum FSH concentrations were measured. Two experiments were performed on anestrous Western White Face (WWF) ewes to independently examine whether or not the ovulations during treatment with a medroxyprogesterone acetate (MAP)-containing sponge and prostaglandin F2á (PGF2á), were due to the direct effects of PGF2á on the ovary or the effects of a rapid decline in progesterone at PGF2á-induced luteolysis. Non prolific Suffolk ewes were used to assess the effectiveness of treatment with medroxyprogesterone acetate (MAP)-containing sponge and prostaglandin F2á (PGF2á) to increase lambing rate. Re-introduction of rams to pre-isolated, mid-anestrous, WWF ewes was used to look at the effect of increased pulsatile secretion of LH on ovarian antral follicular dynamics at different stages of follicular wave development. We also used ovarian transrectal ultrasonography and computer assisted image analysis as non-invasive techniques to investigate whether or not there were correlations between ultrasound image attributes of the ovine CL and changing progesterone concentrations over time, in prolific and non prolific ewes. The results of the present studies showed that, in the ewe, small antral follicles can respond to the injection of FSH to yield a follicular wave more frequently than seen in a normal cycle and in the presence of a large growing antral follicle. Non induced waves can emerge during the growth phase of a wave induced by injection of oFSH. These results bring into question the presence of functional follicular dominance in the ewe. Ovulations occurred after PGF2á injection but during continuous treatment with MAP, but those ewes experiencing a decline in serum progesterone concentrations in the presence of MAP did not ovulate any follicles. We concluded that ovulations occurring after PGF2á injection, in the presence of a MAP sponge could be due to a direct effect of PGF2á at the ovarian level rather than a sudden decline in circulating progesterone concentrations. Treatment of Suffolk ewes with MAP-containing sponges and injection of PGF2á did not increase lambing rate, perhaps due to asynchrony of ovulations. Re-introduction of rams to previously isolated ewes resulted in a subtle increase in LH pulse frequency on the day of ram introduction in ewes in the static phase of a follicular wave. However, there were no consistent changes in follicular dynamics or estradiol secretion in response to this increase in LH pulse frequency. We concluded that changes in LH pulse frequency do not dramatically change ovarian antral follicular dynamics in the anestrous ewe. Both total luteal area and mean spot pixel values for the CL were correlated with the pattern of serum concentrations of progesterone from day 3 to day 15 after ovulation in WWF ewes and from day 3 to day 14 in Finn ewes. There were no significant correlations between progesterone concentrations and spot pixel heterogeneity for either WWF or Finn ewes. We concluded that pixel heterogeneity is a poor indicator of progesterone secretory ability of the CL when compared to mean pixel values. However, luteal area and mean spot pixel values are better but not strong indicators of the functional status of the CL in cyclic ewes.