Fertility in Australia: The role of policy and the labour market

One of the most discussed topics in labour and demographic studies, population ageing and stability, is closely related to fertility choices. This thesis explores recent developments in the fertility literature in the context of Australia. We investigate individual preferences for child bearing, the determinants of fertility decisions and the effectiveness of policies implemented by the government aimed at improving total fertility. The first study highlights the impact of monetary incentives on the decision to bear children in light of potentially differential responses across the native and immigrant population. The second study analyses the role of unemployment and job stability on the fertility choices of women. The final study examines whether the quality-quantity trade-off exists for Australian families and explores the impact of siblings on a child's health and educational outcomes.

Genomic architecture of ecologically divergent body shape in a pair of sympatric crater lake cichlid fishes

Determining the genetic bases of adaptations and their roles in speciation is a prominent issue in evolutionary biology. Cichlid fish species flocks are a prime example of recent rapid radiations, often associated with adaptive phenotypic divergence from a common ancestor within a short period of time. In several radiations of freshwater fishes, divergence in ecomorphological traits - including body shape, colour, lips and jaws - is thought to underlie their ecological differentiation, specialization and, ultimately, speciation. The Midas cichlid species complex (Amphilophus spp.) of Nicaragua provides one of the few known examples of sympatric speciation where species have rapidly evolved different but parallel morphologies in young crater lakes. This study identified significant QTL for body shape using SNPs generated via ddRAD sequencing and geometric morphometric analyses of a cross between two ecologically and morphologically divergent, sympatric cichlid species endemic to crater Lake Apoyo: an elongated limnetic species (Amphilophus zaliosus) and a high-bodied benthic species (Amphilophus astorquii). A total of 453 genome-wide informative SNPs were identified in 240 F-2 hybrids. These markers were used to construct a genetic map in which 25 linkage groups were resolved. Seventy-two segregating SNPs were linked to 11 QTL. By annotating the two most highly supported QTL-linked genomic regions, genes that might contribute to divergence in body shape along the benthic-limnetic axis in Midas cichlid sympatric adaptive radiations were identified. These results suggest that few genomic regions of large effect contribute to early stage divergence in Midas cichlids.

Immunization of male bonnet monkeys (M-radiata) with a recombinant FSH receptor preparation affects testicular function and fertility

Immunization of proven fertile adult male monkeys (n = 3) with a recombinant FSH receptor protein preparation (oFSHR-P) (representing amino acids 1-134 of the extracellular domain of the receptor Mr similar to 15KDa) resulted in production of receptor blocking antibodies. The ability of the antibody to bind a particulate FSH receptor preparation and receptors in intact granulosa cells was markedly (by 30-80%) inhibited by FSH. Serum T levels and LH receptor function following immunization remained unchanged. The immunized monkeys showed a 50% reduction (p<0.001) in transformation of spermatogonia(2C) to primary spermatocytes (4C) as determined by flow cytometry and the 4C:2C ratio showed a correlative change (R 0.81, p<0.0007) with reduction in fertility index (sperm counts X motility score). Breeding studies indicated that monkeys became infertile between 242-368 days of immunization when the fertility index was in the range of 123+/-76 to 354+/-42 (compared to a value of 1602+/-384 on day 0). As the effects observed ate near identical to that seen following immunization with FSH it is suggestive that oFSHR-P can substitute for FSH in the development of a contraceptive vaccine.

The effect of post-weaning growth on the fertility of Brahman cross heifers

In the dry tropics of northern Australia heifers are generally weaned mid-year at about six months of age and experience two dry seasons and a wet season prior to first mating at 2 years of age when only 60% are likely to conceive (Entwistle 19830. Pre-mating liveweight (PMLW) explains much of the variation in conception rate, but year effects explain further variations (Rudder et al 1985).

Influence of nitrogen based supplements on live weight, fertility and mortality of heifers grazing dry season native pasture

Supplements containing urea or biuret were fed in the dry season to yearling and two year old pregnant heifers grazing native spear grass pastures in north Queensland. Liveweight change and survival during the dry season and fertility in the following year were measured. In the first experiment during a relatively favourable dry season, supplementation significantly (P<0.01) reduced liveweight loss in yearling heifers (5 vs. 32 kg). In the following year during a drought, supplement significantly (P<.01) reduced liveweight loss in yearling heifers (32 vs. 41 kg) and significantly (P <0.01) reduced mortalities (23.5% vs. 5.2%) in pregnant and lactating heifers. The supplement had no significant effect on subsequent fertility in either experiment. 14th Biennial Conference.

Developments in controlled green-water larval culture technologies for estuarine fishes in Queensland, Australia and elsewhere

Since 1989, researchers with the Department of Primary Industries and Fisheries (DPI&F) in Queensland, Australia, have successfully used controlled low-water exchange green-water cultures to rear the larvae of estuarine fishes and crustaceans through to metamorphosis. High survivals and excellent fry condition have been achieved for several commercially important endemic species produced for various projects. They include barramundi or sea bass, Lates calcarifer, Australian bass, Macquaria novemaculeata, dusky flathead, Platycephalus fuscus, sand whiting, Sillago ciliata, red sea bream or snapper, Pagrus auratus, banana prawn, Fenneropenaeus merguiensis, and others. The consistent success of our standardised and relatively simple approach at different localities has led to it being incorporated into general fingerling production practices at several establishments in Australia. Although post-metamorphosis rearing methods have differed for each species investigated, due to various biological and behavioural traits and project requirements, these larval rearing methods have been successful with few species-specific modifications. Initially modelled on the Taiwanese approach to rearing Penaeids in aerated low-water exchange cultures, the approach similarly appears to rely on a beneficial assemblage of micro-organisms. Conceptually, these micro-organisms may include a mixture of the air-borne primary invaders of pure phytoplankton cultures when exposed to outdoor conditions. Whilst this would vary with different sites, our experiences with these methods have consistently been favourable. Mass microalgal cultures with eco-physiological youth are used to regularly augment larval fish cultures so that rearing conditions simulate an exponential growth-phase microalgal bloom. Moderate to heavy aeration prevents settlement of particulate matter and encourages aerobic bacterial decomposition of wastes. The green-water larval rearing approach described herein has demonstrated high practical utility in research and commercial applications, and has greatly simplified marine finfish hatchery operations whilst generally lifting production capacities for metamorphosed fry in Australia. Its potential uses in areas of aquaculture other than larviculture are also discussed.

Long-term trends in fertility of soils under continuous cultivation and cereal cropping in southern Queensland. IX. Simulation of soil carbon and nitrogen pools using CENTURY model

Cultivation and cropping of soils results in a decline in soil organic carbon and soil nitrogen, and can lead to reduced crop yields. The CENTURY model was used to simulate the effects of continuous cultivation and cereal cropping on total soil organic matter (C and N), carbon pools, nitrogen mineralisation, and crop yield from 6 locations in southern Queensland. The model was calibrated for each replicate from the original datasets, allowing comparisons for each replicate rather than site averages. The CENTURY model was able to satisfactorily predict the impact of long-term cultivation and cereal cropping on total organic carbon, but was less successful in simulating the different fractions and nitrogen mineralisation. The model firstly over-predicted the initial (pre-cropping) soil carbon and nitrogen concentration of the sites. To account for the unique shrinking and swelling characteristics of the Vertosol soils, the default annual decomposition rates of the slow and passive carbon pools were doubled, and then the model accurately predicted initial conditions. The ability of the model to predict carbon pool fractions varied, demonstrating the difficulty inherent in predicting the size of these conceptual pools. The strength of the model lies in the ability to closely predict the starting soil organic matter conditions, and the ability to predict the impact of clearing, cultivation, fertiliser application, and continuous cropping on total soil carbon and nitrogen.

Successful fertility experiments with cryopreserved spermatozoa of barramundi, Lates calcarifer (Bloch), using dimethylsulfoxide and glycerol as cryoprotectants

The fertility of cryopreserved Lates calcarifer sperm was studied to increase the availability of semen for routine fertilization of stripped eggs and to provide a tool for selective breeding. Semen diluted (1:4 v/v) and frozen (-196 degrees C) with 5% dimethylsulfoxide (DMSO) or 10% glycerol (final concentration) as cryoprotectants was used to inseminate freshly stripped ova. Frozen-thawed sperm were motile for about 4 min after being mixed with seawater. In the DMSO medium, post-thaw sperm activation was immediate after dilution with seawater, but in the glycerol medium maximum motility intensity was delayed for up to 1 min. When eggs and sperm were mixed before the addition of seawater, semen frozen with DMSO as cryoprotectant gave a mean hatch rate (84.1%) no different (P > 0.05) from that of unfrozen semen diluted with Ringer's solution (80.7%) or with DMSO (83.7%), but higher (P < 0.05) than that of semen frozen with glycerol (60.9%). Adding sperm to seawater 30 s before mixing with eggs did not improve the fertility of sperm cryopreserved with glycerol. Eggs inseminated with glycerol-cryoprotected sperm showed higher mortality during incubation than those inseminated with DMSO-cryoprotected sperm. Sperm held in liquid nitrogen for 90 days with DMSO as cryoprotectant yielded acceptable fertilization and hatching rates with semen-to-ova ratios of up to 1:100 (v/v) , and produced fish with no apparent abnormalities over a 29-day period after hatch. These results show that cryopreservation of L. calcarifer sperm is feasible and well suited to a variety of hatchery purposes.

Northern Australia Beef fertility Project (Cash Cow)

Performance measures for monitoring and comparing the reproductive performance of northern Australian beef herds.

Indicator traits in bulls that are predictive of female fertility in cattle

Indicator traits in bulls that are predictive of female fertility in cattle.

Soil fertility in sweetpotato-based cropping systems in the highlands of Papua New Guinea

The main outputs anticipated include enchanced knowledge of key water-nutrient dynamics in relation to key soil management techniques and a suite of improved and practical soil management options in sweet potatoes.

A Need for FSH in Maintaining Fertility of Adult Male Subhuman Primates

Adult fertile male bonnet monkeys (Macaca radiata) were continuously deprived of endogenous follicle stimulating hormone (FSH) support for 240 days by injecting them with 1 ml of characterized monkey antiserum to oFSH every 48 hr; control monkeys received during the same period normal monkey serum instead. Testicular function was assessed at periodic intervals by (a) carrying out differential counting of sperm in the ejaculate obtained and (b) determining the hyaluronidase activity as well as in vitro 3H thymidine incorporation into DNA of testicular tissue removed at biopsy. Both the quality (viability and motility) of the sperms voided and the total sperm counts showed marked decreases as a function of time of immunization, the first significant reduction being noted by 100 days. FSH deprivation affected both the biochemical parameters used to test testicular functionality they being reduced at ∼200 days by 50%-60%. The fertility of these monkeys was evaluated at periodic times after 90 days of treatment by means of mating studies. FSH deprivation had rendered the monkeys incapable of impregnating any of the females used. Testosterone and luteinizing hormone (LH) levels remained unchanged following FSH antiserum injection. With cessation of antiserum treatment testicular function and fertility were completely restored to normalcy, indicating that the observed effect was specifically due to FSH deprivation. This study thus provides conclusive evidence for the involvement of FSH in maintenance of testicular function and fertility in the adult male primate.