The main goals of layer breeding are a result of eeonomie eonditions. GOWE et al. (1993) reported that in egg stock seleetion programs the key traits are egg produetion rate, age at sexual maturity, viability at all ages, egg size, egg shell strength, feed effieieney as weil as fertility and hatehability. However, in praetiee, laying intensity is usually the main seleetion eriterion (WJ,;:ZYK, ...

Over the last twoto three-decade period, the beef industry has made great use of genetic selection tools to improve economically important traits. Much of that improvement is due to the implementation and use of expected progeny differences (EPD). Since beef producers are paid for their animals on the basis of weight, or in some cases by the merit of animal carcasses, most EPD reported in breed...

Present investigation reports the mutagenic efficacy of sodium azide with a view to study its effects on meiotic behavior and phenotypic quantitative traits of Brassica campestris L. Seeds were treated with three concentration of sodium azide i.e. 0.3%, 0.5% and 0.7%, along with control. Morphological/phenotypic parameters studied were plant height, number of primary branches, number of seconda...

The objective of this study was to quantify the genetic variation in normal and atypical progesterone profiles and investigate if this information could be useful in an improved genetic evaluation for fertility for dairy cows. The phenotypes derived from normal profiles included cycle length traits, including commencement of luteal activity (C-LA), interluteal interval, luteal phase length. and...

Selection criteria for yearling bulls commonly include indicators of fertility and carcass merit, such as scrotal circumference (SC) and intramuscular fat percentage (IMF). Genetic correlation estimates between ultrasound traits such as IMF and carcass marbling score (MS) with fertility traits SC and heifer pregnancy (HP) have not been reported. Therefore, the objective of this study was to est...

Data from 113 Dutch organic farms were analysed to determine the effect of cross-breeding on production and functional traits. In total, data on 33 788 lactations between January 2003 and February 2009 from 15 015 cows were available. Holstein-Friesian pure-bred cows produced most kg of milk in 305 days, but with the lowest percentages of fat and protein of all pure-bred cows in the data set. C...

In women, changes in preference during the menstrual cycle have been documented for attractiveness judgements of odour and various physical and behavioural male traits. Although many studies have demonstrated greater attraction to masculine traits, such as male faces, bodies, and voices, at high fertility, several recent studies present null results for these shifts in preferences. Moreover, ev...

Recent human history is marked by demographic transitions characterized by declines in mortality and fertility. By influencing the variance in those fitness components, demographic transitions can affect selection on other traits. Parallel to changes in selection triggered by demography per se, relationships between fitness and anthropometric traits are also expected to change due to modificati...