The overall objective of this research was to define the cellular basis underlying heritable subfertility in roosters homozygous for the rose comb allele (R/R). Fertilization in the hen is preceded by the ascension of motile sperm through the vagina and sperm sequestration within sperm storage tubules (SST). The objective of the first set of experiments was to determine if reduced sperm sequestration could account for subfertility. Sperm sequestration differed between genotypes following intravaginal insemination (p<0.0001). However, sperm sequestration did not differ between genotypes when sperm were incubated with SST in vitro (p>0.05). Therefore, subfertility was attributed to reduced sperm transport within the vagina. To test this hypothesis, an assay was developed to evaluate fowl sperm motility in vitro. Based upon this assay, ejaculates from subfertile males contained smaller subpopulations of highly motile sperm than the ejaculates from controls (p<0.001). The objective of the next set of experiments was to characterize the motility of individual sperm and to identify a mechanism that could account for the genotypic difference in sperm cell motility. Computer-assisted sperm motion analysis evaluation revealed that ejaculates from controls contained 91% motile sperm whereas ejaculates from subfertile males contained 62% motile sperm (p<0.001). The ATP concentration in sperm from subfertile males was 63% less than that of sperm from controls (p<0.001). A link between sperm ATP concentration and immotility was investigated. First, sperm metabolism was evaluated using motility as an endpoint. The genotypic difference in sperm motility persisted when ATP synthesis was limited to glycolysis (p<0.001). Consequently, mitochondrial respiration could not account for the genotypic difference in sperm motility. In contrast, sperm uptake of [1,2-��H] 2-deoxy-D-glucose did differ between genotypes (p<0.001). The activity of key glycolytic enzymes, creatine kinase, and dynein ATPase did not differ between genotypes (p>0.05). Therefore reduced sperm motility did not appear to be due to ATP synthesis, allocation of high energy phosphate bonds along the axoneme, or ATP consumption (p>0.05). In conclusion, subfertility of roosters homozygous for the rose comb allele was attributed to decreased spermatozoal glucose transport. / Graduation date: 1997

Thesis (M.A.)--Eastern Michigan University, 1990. / Includes bibliographical references.

This thesis analyses three aspects of the link between a woman’s educational trajectory and her childbearing behaviour. Special attention is paid to educational field as a further dimension of education next to educational enrolment and educational level. It is argued that this dimension has to be taken into account to fully understand the complex interplay between women’s educational careers and fertility. The empirical investigations are based on Swedish register data for the period 1990 to 2004 and carried out by means of event history analyses. Regarding the impact of women’s education on fertility, this study confirms that educational enrolment generally impedes childbearing. Further, in addition to differences in first, second and third birth risks among women with different levels of education, the analyses reveal strong variations in the fertility behaviour of women with different types of education. To investigate the impact of fertility on women’s educational careers, this study examines how becoming a mother influences a woman’s risk to pursue further training in a different field of education. The effect of motherhood on the risk of educational change varies strongly depending on the field Swedish women initially were trained in. Especially women with degrees in fields in which it is difficult to get established in the labour market are found to have a high risk of educational change. For these women giving birth to a child appears to lead them to strive for further training in a field that offers more stable and family friendly employment prospects. Finally, the study explores the impact of unobserved factors on education and fertility. By estimating a simultaneous hazard equation for a woman’s childbearing behaviour and her choice of educational field, it is shown that women’s decisions about education and fertility are correlated due to the existence of unobserved determinants that simultaneously influence both life domains.

The purpose of this study is to examine what effect social background may have on the timing of becoming a parent in Sweden. By applying event-history techniques to data from the Swedish level of living survey (LNU) we try to separate the direct from the indirect effect of social background on timing of first childbearing. Few previous studies have focused on characteristics of social background and analysis of intergenerational effects on the age of becoming a parent. In this study, we show that the risk of becoming a parent is different for those who are mobile than for the socially non-mobile. The effect of social background on the propensity of becoming a parent is not just indirect via persons own educational careers. When we control for own educational level much of the impact of social background on the propensity of becoming a parent remains. We clearly show the existence of a significant direct effect of social background on the propensity to become a parent.

Fertility rates in sub Saharan Africa (SSA) have been identified to be depicted by a  unique demographic scenario, that sets  the region  apart from other regions in the world. Demographers are particularly keen on comprehending the dynamics surrounding the demographic transition of the sub continent especially with respect to its shift from high fertility rates to low fertility rates.  The decline in fertility embodies the second phase of the demographic transition process. The discourse on fertility rates in the sub continent has been coined to be an anomaly based on its prevalence being an exception in the world. Discussion pertaining to fertility levels in the region in this paper was made  with the purpose of illuminating the factors that account for the region’s high fertility rates, as well as on  fertility discourse in the region, and the variation that characterize its prevalence amongst the countries in the sub continent. Information on the fertility rates revealed that social organization and cultural setting in the region play pivotal roles in forging high fertility rates in the region.

Suitable orchard land in regions of high elevation, arid climates, and alkaline soil conditions is becoming more limited due to urban sprawl. With the loss of suitable farmland, increasing input costs, and the lack of sound fertility information for these regions, fruit growers face challenges in producing high quality fruit to meet local and general market demand. The question that arises is whether fruit growers can supply sufficient quantities of quality fruit to take full advantage of local and global demand. Government data for population, fruit production, and fruit consumption in Utah were reviewed to determine the potential size of the local market, and determine whether growers have opportunities to increase production to meet unsatisfied demand for high quality local produce. In addition to market analysis, fertility-based management strategies are needed to optimize yield and fruit quality in production areas of high elevation, arid climates, and alkaline soils. Three different approaches were used to investigate the effect of phosphorus (P) and potassium (K) on tart cherry fruit quality and yield at high elevations, arid climate conditions, and in alkaline soils. The approaches of this study include: a rate-response evaluation using the industry-standard Triple-16 fertilizer (16-16-16), and comparison of P and K fertilizer formulations to determine the most cost effective sources of these nutrients with regard to yield and fruit quality. Additions of P and K maintained adequate yield and fruit quality, but showed no significant difference among treatments, where historically aggressive nutrient management had been practiced. Fertilizer additions did result in a significant increase in yield and fruit quality where nutrient management programs were historically much less aggressive. There is no advantage of higher cost fertilizer formulations over standard low-cost sources (i.e.; Triple-16). Moreover, there is no significant advantage to splitting fertilizer application over time during the growing season. An analysis of government data indicates that, over the past 40 years, Utah has become a net importer of apples (1997), peaches (1987), and sweet cherries (2005), indicating increased local market opportunities. Increasing the fruit supply to the local market can best be accomplished by increasing yields and fruit quality on existing orchard acreage. Optimizing annual P and K nutrient management is an important key to maximizing yield and fruit quality. The results provide foundational guidelines of nutrient management for optimizing tart cherry production and fruit quality under regionally specific conditions.

The genetic component of mammalian male fertility is complex and involves thousands of genes. The majority of these genes are distributed on autosomes and the X chromosome, while a small number are located on the Y chromosome. Human and mouse studies demonstrate that the most critical Y-linked male fertility genes are present in multiple copies, show testis-specific expression and are different between species. In the equine industry, where stallions are selected according to pedigrees and athletic abilities but not for reproductive performance, reduced fertility of many breeding stallions is a recognized problem. Therefore, the aim of the present research was to acquire comprehensive information about the organization of the horse Y chromosome (ECAY), identify Y-linked genes and investigate potential candidate genes regulating stallion fertility. To achieve theses goals, a direct cDNA (complementary DNA) selection procedure was used to isolate Y-linked genes from horse testes and 29 Y-specific genes were identified. All 29 genes were mapped to ECAY and their sequences were used to further expand the existing map. Copy number analysis identified 15 multicopy genes of which 9 were novel transcripts. Gene expression analysis on a panel of selected body tissues showed that some ECAY genes are expressed exclusively in testes while others show ubiquitous or intermediate expression. Quantitative Real-Time PCR using primers for 9 testis-specific multicopy genes revealed 5 genes with statistically significant differential expression in testis of normal fertile stallions and stallions with impaired fertility. Gene copy number analysis showed that the average copy number of 4 such genes was decreased in subfertile/infertile stallions compared to normal animals. Taken together, this research generated the first comprehensive physical gene map for the horse Y chromosome and identified a number of candidate genes for stallion fertility. The findings essentially expand our knowledge about Y chromosome genes in horses, open a new avenue for investigating the potential role of ECAY genes in stallion fertility which contribute to the development of molecular tools for the assessment of fertility in stallions.

Cryopreservation of gametes and embryos is crucial in fertility treatment and fertility preservation. Preservation of oocytes is a more complicated process than preservation of sperm and embryos. According to recent studies, a new preservation technique called vitrification is found to have higher rates of oocytes-survival after warming    The aim of this study was to evaluate VitriBlast™ Kit, for vitrification of oocytes. Vitrification is an ultra-rapid freezing method in the presence with of high concentrations of cryoprotectants which avoids intracellular ice-crystal formation during the freezing and warming process.     In this study, a total number of 117 immature oocytes were used and 62 of these oocytes were vitrified with VitroBlast™ Kit. During this process two different vitrification devices were used, VitroLoop™ and Cryopette®. After warming, the average survival rate for vitrified oocytes was found to be 61% for VitroLoop™ and 15% for Cryopette® (p&lt;0.001). The remaining 55 oocytes were used as a non-frozen control group and the same incubation method as for vitrified oocytes was used. The survival rate for the control groups was higher than for the vitrified groups (93% versus 35%, p&lt;0.001). The results of this study indicate that VitriBlast™ Kit is not suitable for vitrification of oocytes.

No description available.

Fertility Associated Antigen (FAA) produced by the accessory sex glands and contained within the seminal fluid binds heparin and facilitates capacitation in ejaculated sperm, resulting in improved fertility in bulls capable of producing the protein. In this study, a total of 206 bulls derived from three populations were evaluated for the presence or absence of FAA through utilization of the Repro Test at three semen collections over a 60-d period. Across all collections, the percentage of FAA Negative bulls ranged from 13.64 to 36.11%. Within the three populations, 32, 33, and 67 bulls were observed at three different collections, of which 3.03, 9.09 and 4.48% were FAA Negative at all three collections, respectively. Furthermore, 27.27, 33.33, and 20.90% of bulls were observed to have variations within their FAA status after providing an initial FAA Positive result, respectively. Bull age, sperm concentration, progressive forward motility, percent normal sperm, ejaculate volume, and scrotal circumference were determined to be significantly different between FAA Negative and FAA Positive bulls in at least one collection. However, no consistent trend was observed across populations, or collections within a population, with regard to a relationship between these variables and FAA. Furthermore, of fourteen bulls that produced an ejaculate in which no sperm was detected, 78.57% (n=11) were FAA Positive despite the lack of sperm within the ejaculate. No single variable commonly measured to determine bull fertility was consistent in predicting the FAA status of bulls. The ability to produce FAA precedes puberty and the Repro Test can be used to identify FAA in prepuberal bulls. However, a large percentage of bulls, both prepuberal and peripuberal, are capable of displaying variation in their FAA status (as determined by the Repro Test) over time.