No description available.

No description available.

No description available.

No description available.

This thesis documents the annual profiles of the primary reproductive steroids testosterone (T), 17beta-oestradiol (E2) and progesterone (P4), in the reproductive cycles of male and female blue-tongued lizards, Tiliqua nigrolutea. Data collected from a large captive population over three consecutive reproductive seasons are included. Reproductive cycles are discussed in the context of other viviparous squamate reptiles, while a broader comparative approach is used to consider patterns of steroid biosynthesis and peripheral metabolism. The annual patterns of circulating concentrations of T, E2 and P4 have been characterised for both sexes. In males, peak plasma T (10.9 +/- 3.00 ng ml-1) and E2 (778.0 +/- 120.00 pg ml-1) concentrations occur coincident with late spermatogenesis and observations of mating, respectively. Plasma P4 concentrations remain basal (< 1.2 ng ml-1) throughout the annual reproductive cycle. In females, increasing plasma E2 concentrations (275.2 +/- 33.87 pg ml-1 - 715.1 +/- 106.68 pg ml-1) are associated with vitellogenesis and plasma T peaks (6.3 +/- 0.63 ng ml-1) in the mating and peri-ovulatory period. In pregnant females, plasma P4 concentrations are elevated for the first two thirds of gestation, peaking in the second trimester at 12.7 +/- 1.27 ng ml-1 and falling rapidly prior to parturition. Concurrently, plasma P4 concentrations in non-reproductively active adult females remain basal (1 - 2 ng ml-1) throughout the year. There is good circumstantial evidence for a multiennial reproductive cycle in females. Parturition occurs late in the active season, presumably leaving little time for females to store sufficient fat reserves to become vitellogenic in the following spring: reproductive opportunities are effectively missed in at least one year following a reproductive effort. Observed reproductive behaviours, including agonistic male - male interactions, mating, and parturition, are documented. An investigation of gonadal steroid biosynthetic pathways in this viviparous squamate is presented. This compares variation in the relative contributions of the delta-4 and delta-5 steroidogenic pathways according to sex and reproductive condition. The delta-4 pathway predominates in both sexes, aligning this species phylogenetically with other reptiles. However, there are clear differences between sexes and with changing reproductive condition in the patterns of production of pathway intermediates and end-products. Additionally, detection of a possibly novel polar steroid as a major end-product of steroid biosynthesis in both sexes is reported. Peripheral (extragonadal) metabolism of T and E2 in a number of reproductively relevant steroid target tissues is compared at times of year chosen to represent three clearly distinctive reproductive conditions in each sex. There are differences both between sexes, between tissue types and with changing reproductive condition in the relative proportions of steroid conjugates and non-conjugated derivatives produced. Biosynthetic pathway activity and peripheral steroid metabolism both appear to be plastic in response to changing reproductive condition in Tiliqua nigrolutea. With a comprehensive database of information about the reproductive endocrinology and physiology of Tiliqua nigrolutea, this species is now available as a model to further examine selected aspects of the steroid hormone control of reproductive physiology and behaviour in a cool temperate, viviparous reptile.

With the signing of the Kyoto Protocol, New Zealand must reduce its national greenhouse gas emissions. As New Zealand has a large proportion of its national emissions as methane (~31%), and methane (CH4) has a short atmospheric lifetime, it provides a good target for mitigation strategies. The initial aim of this research was to identify high and low CH4-emitting cattle to assess factors that contribute to low CH4 production. Initial studies using the SF6 tracer technique to estimate CH4 production could not identify consistently high and low CH4 emitters. Research was therefore undertaken to confirm whether this was due to high variation in estimated CH4 yields, and to quantify the within- and between-animal variation in CH4 production when using the SF6 technique. This research showed considerable within- (coefficient of variation, CV = 7-10%) and between-animal (CV = 7-18%) variation in CH4 yield (g CH4/kg DMI) over time when using the SF6 technique. This is larger than the within- (CV = 3%) and between-animal (CV = 10%) variation reported for calorimetry. This led to the recommendation that the SF6 technique not be used in identifying animals for high or low CH4 yield. A power analysis was developed based on the measured variances for the SF6 technique. Results from this analysis provide researchers with important information on the number of animals and measurements per animal required when undertaking CH4 experiments. One of the sources of variation with the SF6 technique is the SF6 release from permeation tubes. Estimated CH4 yield increases by approximately 8.5% when going from a release rate of 3 mg SF6/day to a rate of 5 mg SF6/day. Further, an in vitro study indicated that SF6 release from permeation tubes is approximately 8% lower in rumen fluid than in air. While further research is required to confirm these results, they emphasise the need to allow time for the release rate to stabilise in the rumen for 4-5 days prior to undertaking measurements. It also led to the recommendation that release rates used in experiments should be within a narrow range, and balanced across experimental treatments.

Improvements in breeding success are needed for conservation of endangered birds such as the New Zealand kakapo. A potential method to stimulate breeding is treatment with exogenous hormones. Hormone treatment is used in captive breeding programmes for endangered mammals but reliable techniques are not available for birds. Gonadotropin releasing hormone (GnRH), the principal hormone controlling reproduction, has been used to induce ovarian growth and ovulation in seasonally anoestrous mammals. The goal of the research in this thesis was to determine the potential of GnRH for hormone treatment in birds. The Japanese quail (Coturnix coturnix japonica) was used in the current research. Female quail held outdoors with male quail and with access to nesting materials and nest sites showed clear seasonal patterns in the width of the cloacal opening (indicative of oviduct development) and FSH concentrations, whilst LH concentrations were low during winter and increased during spring and summer. Prolactin concentrations were elevated in birds incubating eggs in nests and birds caring for young. Photoperiodically induced gonadal growth and regression were described in detail for male and female quail under controlled conditions. Testicular and ovarian growth was preceded by increased LH and FSH concentrations and accompanied by increased gonadal steroid concentrations. Administration of various types of GnRH stimulated luteinising hormone (LH) secretion in sexually regressed female Japanese quail. LH responses to cGnRH-II were greater than those to cGnRH-I. Low doses of buserelin stimulated similar LH responses to cGnRH-II, whilst high doses of buserelin and D-Lys6Trp7Tyr8-GnRH induced sustained LH secretion. Single daily injections of various doses of cGnRH-II, buserelin or D-Lys6Trp7Tyr8-GnRH in saline or polyvinylpyrrolidone (PVP) did not induce elevated baseline LH or stimulate ovarian growth. Repeated injections of D-Lys6Trp7Tyr8-GnRH did not increase LH concentrations over a short-term period. Continuous infusion of D-Lys6Trp7Tyr8-GnRH by osmotic mini-pump severely blunted the LH response and did not stimulate ovarian growth. Future studies using quail exposed to marginally stimulatory photoperiods will offer the opportunities to determine the effects of GnRH in birds under conditions which mimic photoperiod changes during the breeding season. Further studies on the potential development of a hormone treatment programme will continue to offer a promising future for endangered avian species including the New Zealand kakapo.

To study the effects of feeding and diet on postnatal development of the small intestine in newborn piglets during the time 0 - 24 hours after birth, three studies were conducted: 1. Unsuckled newborn piglets were fed from a bottle with colostrum or milk from either sows or cows, infant formula, or water. After 24 hours intestinal development was compared with that in piglets at birth and others naturally suckled. Sow colostrum caused greater increases in weight and length of the small intestine than did any of the other diets. The increases were due to mucosal cell swelling caused by cellular protein accumulation, hyperplasia and, in the duodenum, hypertrophy. Feeding sow colostrum increased mucosal lactase activity. Cow colostrum caused decreases in mucosal RNA levels. Increases in the DNA content of the intestinal mucosa occurred in all groups, including the water fed group. Colostrum feeding also enhanced pancreatic growth and feeding infant formula increased liver weight. 2. The effects of enteral feeding on small intestinal development were investigated by feeding nutrient solution to unsuckled newborn piglets by orogastric tube or parenterally. Both groups after 24 hours had greater intestinal development than did the piglets at birth. The development was most pronounced in the duodenum and lower ileum. Apart from a greater small intestinal length in the orogastrically fed piglets there were no significant differences between the orogastrically and parenterally fed groups. 3. To investigate the effects of sucking per se on small intestinal development, groups of unsuckled piglets were fed for 24 hours with either sow colostrum or infant formula by orogastric tube or being allowed to suck from a bottle. Sucking did not affect intestinal development whereas colostrum, regardless of how it was fed, had significantly greater effects on intestinal development than did infant formula. For the colostrum fed piglets the intestinal length, tissue weight, circumference, wall thickness, villous height and width, RNA content, protein:DNA ratio and RNA:DNA ratio were all significantly greater than for those fed infant formula. In the duodenum the estimated cell migration rate was faster and mucosal cell replacement time was shorter than in other parts of the small intestine, regardless of the diet fed. The greater villous height in the piglets fed sow colostrum was most likely due to the combined effects of cellular swelling and an increase in the number of villous cells. These results indicate that (a) sow colostrum causes cellular swelling related to colostral protein accumulation, cell hyperplasia and, in the duodenum, hypertrophy, (b) there is a basal rate of mucosal cell division which contributes to mucosal growth regardless of diet and method of feeding, (c) the duodenum exhibits a greater growth and sensitivity to the trophic effects of colostrum compared to other parts of the small intestine, (d) feeding cow colostrum to newborn piglets causes a pronounced decrease in mucosal RNA content and (e) diets affect postnatal development of the small intestine whereas the route or method of feeding has no significant effects on small intestinal development in piglets during the first 24 hours after birth.

No description available.

Causes of morbidity and mortality were investigated for 108 green turtles (Chelonia mydas) stranded in south-east Queensland between 1990 and 1996. This study was undertaken as part of a broader carcass salvage program for south Queensland, and within the context of a population study of C. mydas in the Moreton Bay feeding ground. Accurate pathological characterisation of disease in C. mydas was achieved by detailed necropsy and histological examination. Varied inflammatory responses and degenerative changes were observed in stranded C. mydas. Supportive disciplines of microbiology, parasitology, and clinical chemistry were used to elucidate aetiology and pathogenesis of selected conditions. Heavy metal and pesticide levels were assessed in a sub-sample of turtles. Direct anthropogenic causes (including trauma, foreign body ingestion and drowning) accounted for 34% of mortalities of C. mydas in this study. The majority of the trauma cases were turtles with skull fractures resulting from blunt impacts. The remainder had boat propeller injuries, or miscellaneous trauma. Almost half of the turtles with lethal boat propeller damage had evidence of pre-existing disease which may well have predisposed them to boat strike, emphasising the importance of full necropsy examination, even when the cause of death appears obvious. Fishing line was the only ingested foreign body consistently implicated in the production of fatal intestinal obstruction. Marine turtle fibropapillomatosis, a panzootic viral disease which is considered to involve some indirect anthropogenic factors, accounted for 7% of mortalities. The findings in this study were consistent with much of the previously described pathology of this condition. Naturally-occurring diseases (for which human influences are unknown) accounted for the remaining 59% of strandings. Coccidiosis, caused by Caryospora cheloniae, was recorded for the first time in wild C. mydas. It occurred both as an epizootic (in 1991) and as sporadic cases. A variety of manifestations, including disseminated and enteric forms, were recognised. Infection with a Cryptosporidium-like protozoan appeared to occur concurrently with coccidiosis in one turtle in this study. Attempts to establish experimental coccidial infections in hatchling C. mydas were unsuccessful. Infections with cardiovascular (spirorchid) flukes were almost universal in stranded C. mydas in this study. They ranged from mild, incidental findings (such as occasional fluke vii egg granulomas evident microscopically in otherwise normal tissues) to a variety of severe changes, including thrombosis, which were likely to have produced morbidity. The present study clarified the range of cardiovascular lesions associated with spirorchidiasis, including the sequence of thrombus resolution and exteriorisation from vessels. In some cases spirorchid vasculitis was associated with fatal disseminated bacterial infections. Other sporadic, naturally-occurring diseases included mycotic pneumonia, bacterial meningoencephalitis and a miscellany of gastrointestinal conditions, including chronic intestinal tympany and obstipation, for which the underlying cause could not always be determined. Evidence indicated that gastrointestinal motility in C. mydas was prone to both direct and indirect disturbance and that tympany and obstipation could be final common outcomes of a range of insults. Eighteen abnormally buoyant turtles were examined during this study. The cause could usually be ascribed to an underlying disease, including (in decreasing order of frequency) trapped internal gas, usually intestinal; neurological disease such as traumatic brain injuries; and pulmonary disease. In two cases, no underlying cause was detected. Trace metal (arsenic, cadmium, mercury, selenium and zinc) concentrations were determined in the livers and kidneys of 50 turtles of mixed species (mostly C. mydas). These results were considered to provide baseline data for sea turtles in SE Qld. This study offered the largest dataset available for some metals in C. mydas, and provided evidence of high background levels of cadmium as a normal feature for the species. Some unusual age–related trends in metal accumulation were detected. Concentrations of cadmium, zinc and selenium in the kidney decreased with increasing age, whereas zinc concentrations in the liver tended to increase. Determining the impact of disease on wildlife populations is an increasingly necessary task, which will require multidisciplinary teams. Necropsy surveys like the present study are an essential component of the growing field of conservation medicine. In addition to providing data relevant to management, such as the relative proportions of anthropogenic and naturally-occurring mortalities, necropsy surveys can identify a range of endemic pathogens, and help to collect prevalence data for determining disease impacts at the population level.