This dissertation investigated bull fertility in Brown Swiss cattle. Chapter One offers an overview and an outline for the contents of the dissertation. Chapter Two provides a literature review on topics such as the importance of reproduction performance in dairy cattle, the importance of dairy bull fertility, and different genetic analyses. Chapter Three focuses on the evaluation of dairy bull fertility using confirmed pregnancy records. The analysis included both factors related to the bull under evaluation and factors associated with the cow that receives the unit of semen. The results showed that there is a substantial variation in conception rate among bulls, and the prediction of service sire fertility is feasible. These findings represent the foundation for the development of novel tools that will allow the dairy industry to make enhanced management and selection decisions on Brown Swiss male fertility. Chapter Four focuses on understanding the genetic basis of male fertility in Italian Brown Swiss dairy cattle. The analyses included whole-genome scans and gene-set analyses to identify genomic regions, individual genes, and genetic mechanisms affecting Brown Swiss bull fertility. These analyses identified genomic regions, individual genes, and gene-set related to male fertility. Additionally, the results showed genomic regions with marked non-additive effects associated with bull fertility. This comprehensive study contributes to a better understanding of the genetic basis of male fertility in cattle. Chapter Five aims to assess the feasibility of predicting male fertility in Brown Swiss cattle using genomic data under different scenarios, including within-country, across-country, and incorporating markers with large effect. The analyses included the use of linear kernel-based regression models fitting all SNPs or incorporating markers with large effect, using five-fold cross-validation. The findings showed that the prediction of service sire fertility using genomic data achieves moderate to high accuracy and the inclusion of markers with large effect is a promising alternative to the standard approach. However, the use of an across-country reference population did not outperform the standard within-country approach. Genomic predictions of service sire fertility can help Brown Swiss breeders make accurate genome-guided selection and management decisions. Chapter Six evaluates the presence of homozygosity in Italian Brown Swiss dairy cattle and assesses its association with bull fertility. The findings showed that inbreeding and increased homozygosity have a negative impact on male fertility in Italian Brown Swiss cattle. The quantification of homozygosity can contribute to minimizing the inbreeding rate and avoid its negative effect on fitness-related traits, such as male fertility. Lastly, a final Chapter is provided with some concluding remarks.

Since the time of domestication more than 10,000 years ago, cattle have played an increasingly crucial role in the development of human civilizations. Progress has been quite remarkable since the turn of the century; the sequencing of the bovine genome in 2009 launched new avenues for furthering our understanding of theoretical and practical aspects of cattle genetics. Covering a vast array of questions, this book reviews major topics from molecular and developmental genetics, disease resistance and immunogenetics to genetic improvement of dairy and beef breeds, addressing all current problems in the field. This second edition includes a new team of authors and completely new chapters on the genetics of fat production, nutrition, feed intake and efficiency, growth and body composition. Fully updated throughout, it provides a valuable resource on cattle genetics for researchers, breeders, veterinarians and postgraduate students.

This dissertation deals with the genetic and genomic analyses of fetal loss and stillbirth in dairy cattle. The first chapter focuses on the genetic analysis of fetal loss in dairy cattle. The genetic analysis was performed to unravel whether fetal loss is a heritable trait, and hence, whether it will respond to genetic selection, and to what extent current fertility traits, such as daughter pregnancy rate, heifer conception rate and cow conception rate currently included in national evaluations of US dairy cattle are associated with fetal loss. This study estimated that fetal loss is a heritable trait, and the magnitude of heritability estimates suggest an important scope for genetic selection. Additionally, fetal loss traits are weakly correlated with current fertility traits included in the national genetic evaluation and thus current selection and breeding efforts have little or no impact on reducing the incidences of fetal loss. The second chapter focuses on dissecting the genetic basis of fetal loss with an aim of finding and characterizing genomic regions, individual genes, and pathways responsible for the genetic variation of fetal loss trait in dairy cattle. Two complementary studies were performed, namely a whole-genome association study and a subsequent gene-set analysis. These studies identified genomic regions, and particularly individual genes and pathways responsible for pregnancy maintenance, placental development, and fetal growth. These findings contribute to a better, deeper understanding of the genetic architecture of fetal loss in dairy cattle and provide opportunities for improving pregnancy success in dairy cattle via marker-assisted selection. The third chapter aims to predict yet-to-be observed fetal loss phenotype in dairy cattle using dense SNP genotype information of cows, bulls, and embryo and considering the environmental effects, health history, and lactation performance. Phenotypic prediction of fetal loss was evaluated using alternative approaches, including kernel-based models in linear and threshold framework. These genomic prediction models could identify with reasonable accuracy the proportion of cows that had a high probability of maintaining a successful pregnancy or experience fetal loss to a given insemination. Overall, the implementation of these predictive tools will allow dairy farmers to make accurate genome-guided management decisions on reproductive management, mating, and culling. The fourth chapter deals with genetic evaluations of stillbirth for five US dairy breeds viz., Ayrshire, Guernsey, Milking Shorthorn, Brown Swiss, and Jersey. The fourth chapter has four primary tasks i) characterizing stillbirth data in terms of stillbirth rates and their distributions in five US dairy breeds ii) determining the extent to which stillbirth data were recorded in the national database iii) performing single-breed genetic evaluations using Sire-maternal grandsire model iv) determining the feasibility of routine genetic evaluations of stillbirth for these breeds, given the currently available stillbirth data. Our results based on available stillbirth data resources suggest that national genetic evaluations of stillbirth are feasible in Brown Swiss and Jersey. However, reliable genetic evaluations of stillbirth in Ayrshire, Guernsey, and Milking Shorthorn require further data reporting on stillbirth.

Mason's World Encyclopedia of Livestock Breeds and Breeding describes breeds of livestock worldwide as well as a range of breed-related subjects such as husbandry, health and behaviour. This definitive and prestigious reference work presents easily accessible information on domestication (including wild ancestors and related species), genetics and breeding, livestock produce and markets, as well as breed conservation and the cultural and social aspects of livestock farming. Written by renowned livestock authorities, these volumes draw on the authors' lifelong interest and involvement in livestock breeds of the world, presenting a unique, comprehensive and fully cross-referenced guide to cattle, buffalo, horses, pigs, sheep, asses, goats, camelids, yak and other domesticants.