Given finite resources, intense investment in one life history trait is expected to reduce investment in others. Although telomere length appears to be strongly tied to age in many taxa, telomere maintenance requires energy. We therefore hypothesize that telomere maintenance may trade off against other life history characters. We used natural variation in laboratory populations of Atlantic silv...

Soil fertility and nutrient-related plant functional traits are in general only moderately related, hindering the progress in trait-based prediction models of vegetation patterns. Although the relationships may have been obscured by suboptimal choices in how soil fertility is expressed, there has never been a systematic investigation into the suitability of fertility measures. This study, there...

Female fertility is one of the most economically important traits for the dairy cattle industry. Because of a few decades of selection mainly for higher milk production, many dairy farms around the world suffer from the consequences of female fertility loss. The aims of this thesis were to study the international genetic evaluation of female fertility traits, to quantify the bias of analyzing m...

Current industry estimates of reproductive performance for cattle, sheep, and swine operations indicate that males contribute significantly to fertility failures. This appears to be due to the use of subfertile individuals and emphasizes the need for additional research in identifying characteristics of sperm that compromise fertilization. In theory, sperm characteristics, such as motility or t...

Introduction Fertility is a very complex trait, difficult to define, to record and to evaluate all the factors that influence fertility. Fertility is strongly influenced by environmental effects and in part by genetics, the male for fertilization and the female for conception. In general, the fertility trait is hereditary but only to a small degree. There does however exist sufficient genetic v...

to estimate the genetic parameters for production and reproduction traits in holstein cows, information from 15 herds recorded by animal breeding center of iran during 1980 – 2004, were employed. estimations were made using restricted maximum likelihood method under an animal model ranging df-reml and matvec software. estimates of heritabilities for yield traits were moderate and ranged from 0....

VII-VIII List of abbreviations XIV List of tables XVI List of figures XVIII List of appendices XXVI 1 2 2.1 2.1.1 2.1.1.1 2.1.1.2 2.1.1.3 2.1.1.4 2.1.1.5 2.1.1.6 2.1.1.7 2.1.2 2.1.2.1 2.1.2.2 2.2 2.2.1 2.2.2 2.3 2.4 2.4.1 2.4.1.1 2.4.1.2 2.4.2 2.4.3 Introduction Literature review Boar reproductivity Boar sperm quality traits Appearance of semen Sperm concentration Sperm motility Semen volume Pl...

VII-VIII List of abbreviations XIV List of tables XVI List of figures XVIII List of appendices XXVI 1 2 2.1 2.1.1 2.1.1.1 2.1.1.2 2.1.1.3 2.1.1.4 2.1.1.5 2.1.1.6 2.1.1.7 2.1.2 2.1.2.1 2.1.2.2 2.2 2.2.1 2.2.2 2.3 2.4 2.4.1 2.4.1.1 2.4.1.2 2.4.2 2.4.3 Introduction Literature review Boar reproductivity Boar sperm quality traits Appearance of semen Sperm concentration Sperm motility Semen volume Pl...

This study provides estimates of genetic parameters for various diseases, fertility and 305-day milk production traits in dairy cattle using data from a UK national milk recording scheme. The data set consisted of 63891 multiple lactation records on diseases (mastitis, lameness, milk fever, ketosis and tetany), fertility traits (calving interval, conception to first service, number of services ...

Fertility varies within a population due to combinatorial contributions of heritable neuroendocrine variations. A better understanding of these variations can lead to mathematical models that could predict which combination of neuroendocrine traits may improve fertility. Our laboratory has identified neuroendocrine traits responsible for fertility variations within our white-footed mouse popula...