OLICINOGENIC factors (col factors) are transferred among different Hfr cor F+ and Fstrains of Escherichia coli K-12 as extrachromosomal particles (FREDERICQ and BETZ-BAREAU 1953; NAGEL DE ZWAIG, A N T ~ N , and PUIG 1962; CLOWES 1963). While some factors, like colE, and colE,, do not affect the fertility of donor strains, others, for example colB or colI, have been reported either to cause fert...

Throughout the world, cattle producers are interested in identifying the most fertile bulls, whether for use in AI or natural service. Unfortunately, although researchers and clinicians have tried for “nearly a century to develop techniques to accurately predict the fertility of a semen sample from an individual male, the goal has not been achieved” (Amann and Hammerstedt 1993). Why? This is du...

Decreased fertility in dairy cows is widespread and economically undesirable. Current management strategies to prevent decreased fertility are exploiting the close relationship between negative energy balance in transition cows and subsequent decreased fertility. However, there is a continuous need for more information regarding the effects of different strategies on fertility. This thesis eval...

The most important reason for studying population is to gain better understanding how societies function and change. In the study of demography, fertility is the most important and perhaps the most complicated aspect of the population. It plays a significant role in the size, composition and distribution. The importance of demographic study lies on population growth can affect our lives in a va...

This paper examines the ethnic differentials in fertility in Malawi using data from the 2000 Malawi Demographic and Health survey. Fertility was estimated for each ethnic group using various procedures and multiple regressions were employed in order to understand factors responsible for ethnic differentials in fertility in the country. Although all ethnic groups in Malawi exhibit high fertility...

Bull fertility may be defined as the process by which spermatozoa fertilize and activate the ovum and then support embryonic development. Bull fertility is a complex trait having relatively low heritability and plays a vital role for efficient production and reproduction of bovine. Various mechanisms involved in regulating bull fertility associated phenotype and reliable biomarkers are poorly d...

Despite extensive research, doubts remain regarding the degree of correspondence between prior stated fertility preferences and subsequent fertility behavior. Preference instability is a factor that potentially undermines predictiveness. Furthermore, if other predictors of fertility substantially explain fertility, then knowledge of preferences may contribute little to explaining or predicting ...

This study examines households’ fertility variations in response to expected permanent shifts in the return to education. Wage premiums measure the return to education because their long-run movements are driven by factors exogenous to the fertility process. The results indicate that high education parents’ fertility responds negatively to changes in the expected return to college and negativel...

Human fertility has declined in all of the Middle East and North African (MENA) countries in the recent years, Iran had the largest decline, however. What factors have affected the fertility decline in Iran, and as compared with other MENA countries, is the question of this paper. Fertility, higher education, and other measures were used for comparison. Regression analysis was also carried out ...

OBJECTIVE The aim of this study was to investigate practice behaviours of Swedish physicians with regard to discussing the impact of cancer treatment on fertility with paediatric oncology patients and their parents, and to identify factors associated with such discussions. METHODS A cross-sectional survey study was conducted targeting all physicians in Sweden working in paediatric oncology ca...